A
Chemical Safety Considerations,
Definitions, Information, Small
­Volume Conversions and Formulas
CHEMI CAL S & MAT ER I A L SA FET Y DATA SH EETS (MSD S)
MSDS Online
http://www.msdsonline.com
This is an online resource for all MSDS and Chemical Abstracts Services (CAS)
information. You will have to register, but it only takes a minute.
MSDS.com
http://www.msds.com
Periodic Table of Elements
http://www.webelements.com
This site has information regarding the periodic table of elements.
A F EW BAS I C C H EMI ST RY D EFI N I T I O N S
ACIDS: Acids are compounded solutions with a pH of less than 7. Acids neutralize alkalis
such as developers. An acid will turn a blue litmus paper a pink-red. Acids are compounds
containing hydrogen that can be replaced by a metal to form a salt; that is, the metal sodium
will replace the hydrogen atom in hydrochloric acid to form the salt, sodium chloride. Acid
strength affects two of the most common functions: imparting a sour taste and creating an
acid environment to limit microbial growth.
NOTE ON ACIDS AND WATER: Heat is released when strong acids are mixed with
water and increasing the amount of acid adds to the level of that heat, releasing more heat. If
you add water to acid, you will create an extremely concentrated solution of acid immediately
at the point of the addition. So much heat is released that the solution may actually boil violently, causing eruptions of concentrated acid. Conversely, if you add acid to water, the solution that forms at the point of the addition is very dilute, and the level of heat released is not
sufficient to cause a violent reaction. Remember Triple A . . . Always Add Acid to water and
never the reverse.
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(e.g., iron and copper). A base that dissolves in water is
called an alkali (e.g., sodium carbonate).
BUFFER: Weak acid(s) or base(s) dissolved
in water that hold the pH near to a constant value
when an acid or base is added. Buffering is the ability of a weak acid/salt combination, such as citric
acid and sodium citrate, to control the amount of
free ­hydrogen ions. When certain amounts of acid
Citric acid has the widest effective buffer range—from
pH 2.5 to 6.5. Tartaric acid can only be used for buffering between pH 3.0 and 4.5.
DELIQUESCENT: A deliquescent chemical is
one that readily absorbs moisture from the air. Salts
are a prime example.
pH: One explanation of the acronym pH is that it’s
an early twentieth-century acronym from the German
word potenz (meaning “power”) and hydrogen, or the
power of hydrogen. A pH number designates a numerical value assigned to an aqueous solution to indicate
APP–1
Jacquie Mahan, Self as Kid, 2003
Jacquie graduated from the Art Institute of Boston a few years ago and
went on to own and operate the Mahan Gallery in Columbus, Ohio, which
was recognized as one of the most influential new galleries in the United
States. This self-portrait explains a lot about her sense of humor and her
experiences in junior high.
(Courtesy of the Artist)
that it is either acidic or alkaline. It also represents a
chemical symbol for the logarithm of the reciprocal
of the hydrogen ion concentration in gram atoms per
liter. What you need to know, in the context of this
book, is that it informs you of the acidity or alkalinity
of the chemistry you are using.
SALT: A salt is formed when an acid and a
base are mixed and the acid releases H+ ions, while
ALKALIS: Alkalis are compounded solutions with
a pH greater than 7. Alkalis are the assorted soluble
metallic hydroxides that neutralize acids to form salts.
An alkali can also be a compounded salt. It functions
as an accelerator in photographic developing formulas
the base releases OH– ions. This process is called
­hydrolysis and creates an ionic compound. The pH of
the salt depends on the strengths of the original acids
and bases:
Acid
Base Salt pH
red litmus paper blue. Examples of alkalis are sodium
strong
strong
pH = 7
carbonate and borax.
weak
strong
pH > 7
strong
weak
pH < 7
weak
weak
depends on
(often potassium and sodium hydroxide). Alkalis turn
ANHYDROUS:
Meaning
a
solid
substance
­without water or crystallization.
BASE: Bases are the chemical opposite of acids
and react with acids to produce water and to form salts
which is stronger
(or their solutions). Some general properties of bases
include bitter taste, slick texture (like soap and water),
SATURATED SOLUTION: Definition of a solu-
violent reaction with acids, caustic to organic matter,
tion that cannot accept any more solid (solute) at a
and turning red litmus paper blue. A base is a ­substance
given temperature without leaving sediment in the
that will neutralize an acid but will not dissolve in water
solution. An example of this is the preparation of
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
or base are added, the system resists changes in pH.
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saturated potassium or ammonium dichromate for
­
simply common sense. However, if you are working
gum bichromate sensitizing (e.g., potassium dichro-
in a home lab, and you have children or pets, it is
mate saturates at 10%–13%).
SOLUBILITY: The maximum weight of a sub-
imperative that you store your chemistry in a safe
and secure place. Prohibit any eating, drinking, and
stance that will dissolve completely in a given volume
splashing in the ­toning area. Prevent skin absorption
of solvent and at a specific temperature.
by keeping chemicals from contacting the skin or
SURFACTANT: An agent, such as Tween, that
eyes. If you have sensitive skin, or your skin has cuts,
reduces the surface tension of a liquid, enabling it to
or abrasions, protect it with some type of separation
more easily penetrate a paper substrate.
such as tongs, splash goggles, and nitrile gloves.
Safety goggles are essential when mixing powdered
HOW CHEMICALS CAN AFFECT THE BODY
♦♦ Breathing: Airborne chemical matter and vapors
in the form of gases can enter the body through your
nose and mouth. Work in a well-ventilated environment, preferably outdoors or using ventilation that
will not pull the vapors past your face on their way
to an exhaust fan. Paper painter’s masks offer only
modest protection against chemicals and practically
none against harmful fumes.
chemistry, because eyes will readily absorb and pass
contaminants along to the rest of the body. If you
wear contact lenses, be extra cautious to prevent the
powders and chemical fumes from getting between
your contact lenses and your eyes.
IF YOU ARE WORKING WITH DANGEROUS
CHEMICALS, HAVE THE SOLUTION TO AN
ACCIDENT ON HAND. An example of this would be
if you were using potassium cyanide (KCN) as a fixer for
wet plate collodion. It would be essential that you have
♦♦ Ingestion: It is a bad idea to eat while work-
several bottles of 3% hydrogen peroxide (drugstore vari-
ing in the lab, or with chemistry, because you are
ety) with you to convert a dangerous spill to an inconse-
quite likely going to ingest that same chemistry. Eat
quential one. Hydrogen peroxide will change potassium
somewhere else.
cyanide (health hazard Level 3) to a harmless potassium
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
♦♦ Absorption: Chemistry can enter the body
cyanate (health hazard Level 1). The ratio for this con-
through the skin and get into the bloodstream.
version is 6 parts hydrogen peroxide to 10 parts potas-
Open cuts or healing wounds on your skin can be
sium cyanide. If you splash or spill KCN on your skin,
an avenue for absorption as well. Wear barrier
don’t take time measuring the proportions; just flood
gloves and a mask when mixing chemistry. Gloves
the area of the splash with hydrogen peroxide several
may present a number of problems. Commonly
times and wash with water.
available types are made from a variety of materials, not all of which provide an adequate barrier
from specific chemicals. Gloves made of nitrile,
FI R ST A I D
available from laboratory and chemical supply
First Aid for Ingestion of Acids and Alkalis
houses, work well for most chemicals that you will
Curiously, the signs and symptoms for ingestion of
use in alternative process. Except for mild chemi-
acids and alkalis are quite similar, as are the recom-
cal usage, avoid latex or kitchen gloves, because
mendations for treatment. In the past, if an acid was
these are susceptible to chemical reactions and
swallowed, the immediate response was to neutralize
are often clumsy.
the acid with an alkali drink (e.g., sodium bicarbonate,
Protecting Yourself: Be Prepared
several glasses of milk or milk of magnesia, or eight
to twelve antacids). If an alkali was not at hand, then
The key to chemical safety is controlling the degree
the response was to force the victim to rinse the mouth
of exposure to the hazards encountered in the mix-
area repeatedly.
ing and use of all chemistry. Ingestion and absorp-
Symptoms and signs associated with significant
tion are easy to protect against in a working lab, it’s
alkali-induced tissue injury include pain in the mouth
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2. The chemical burn penetrated through the first
abdominal pain, and hematemesis . . . a nice way to
layer of skin, and the resulting second-degree
say vomiting of blood. If the larynx is involved, local
burn covers an area more than 2–3 inches in
edema may produce respiratory distress and a hoarse
diameter.
voice. Veterinarians recommend giving a solution of
one part vinegar to four parts water. Rinse the mouth
with water or saline solution and call for medical assistance in either acid or alkali events.
There is disagreement over the effectiveness of
having the victim drink large quantities of water. My
friend Dr. Jacek Mostwin, at Johns Hopkins, says that
the water simply makes the injury spread and that acid
or alkali ingestion is not really a first aid situation at
all . . . you need professionals right away. One thing is
for sure . . . DO NOT INDUCE VOMITING. This is
especially true for hydrofluoric acid ingestion.
That said, here are the basic immediate first aid
recommendations for both acid and alkali ingestion:
♦♦ Do NOT induce vomiting.
♦♦ Do NOT attempt neutralization.
3. The chemical burn occurred on the eye, hands, feet,
face, groin, or buttocks, or over a major joint.
Poison Control Telephone: 1-800-222-1222
If you’re unsure whether a substance is toxic, call the
poison control center at this number: (800) 222-1222.
This is the telephone number for every poison center
in the United States. Call this number 24 hours a day,
7 days a week to talk to a poison expert. If you seek
emergency assistance, bring the chemical container or
a complete description of the substance with you for
identification.
C H EMI ST RY & SA FET Y
♦♦ Do not place an exhaust vent above your face. If
♦♦ Do NOT give oral fluids.
you are building a darkroom, install the exhaust in
♦♦ Do NOT give activated charcoal (for alkali).
the floor or, better yet, do as we do at the College
♦♦ DO rinse the mouth with saline or water for acid.
of Art and Design at Lesley University and build
♦♦ DO remove visible material from mouth with water
your ventilation system into the sink itself so that
or saline (for alkali).
♦♦ DO call 911 and request immediate medical ­assistance.
First Aid for Skin Contact
If an acid or corrosive chemical is splashed on the
skin, immediately proceed to the nearest sink, or
emergency shower, and flush the affected area for at
least 15 minutes. If the chemical is on your clothing,
remove all contaminated clothing.
If a chemical splashes in the eye the immediate
response is to flush the eye repeatedly with warm water
or first aid saline solution eyewash. If an acid, make a
very dilute solution of sodium bicarbonate and use that
as well. If an alkali, repeatedly flush with water, or saline
solution, and rinse with a very dilute solution of boric
acid. In all cases, call for professional medical help.
Seek Emergency Medical Assistance If:
the fumes are vented before reaching your face.
Having an exhaust above your face just pulls all
of the fumes past your eyes, nose, and mouth on
their way to the vents. The fan and exhaust capacity should be able to completely exchange the air in
the room every 3–6 minutes. Consult with an air
quality company for the specifics that will be best
for your space.
♦♦ Prevent chemical material from becoming airborne
through careful handling and mixing of liquids and
powders. Work slowly and don’t splash.
♦♦ Cover trays and tanks when not in use to prevent
vapors from filling your working space. Sheets of
Plexiglas® work well. Label each sheet with the
chemical that it covers so that it is always used for
the same chemicals.
♦♦ Triple A. When mixing, Always Add Acid to
1. The victim has signs of shock, such as ­fainting,
water; never add water to acid. In this way,
pale complexion, or breathing in a ­notably
which is the only way, heat produced by the acids
­shallow manner.
will not cause a splattering acidic liquid eruption.
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
and throat, drooling, pain on swallowing, vomiting,
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♦♦ When weighing chemicals on digital gram scales,
MSDS web sites or by requesting MSDS
never place raw chemicals on the weighing platform
data sheets from the companies that sup-
of the scale. Always place a weighing paper or a
ply you with chemistry. If you intend to use
plastic/paper cup on the scale to hold the chemistry.
any of these chemicals in a class situation, it
Always weigh the paper or cup before depositing
is imperative and mandatory that you have
the chemical, and re-calibrate your scale to zero by
MSDS data sheets on hand in the event of an
pressing “TARE” so that the chemical weight will be
emergency.
the only thing being weighed.
♦♦ Prior to working with any chemical that you are not
familiar with, be sure to read the chemical’s MSDS
data sheet to understand its traits and how to deal
with it in the event of an accident or emergency. Mix
chemistry in glass or plastic containers—never metal.
♦♦ Always wear gloves and safety glasses when weighing
and mixing chemistry.
Dichromates: Safety and Disposal
Dichromates—ammonium, potassium, and sodium
versions—are
potentially
hazardous
chemicals,
and care should be taken in both their use and disposal. Be very careful to avoid breathing a dichromate dust, because it is toxic, and allowing the
chemical to come in contact with your skin. Do not
♦♦ Always use a plastic funnel to prevent spilling and
touch your skin, mouth, or eyes when working with
splashing when transferring chemistry, solids, or
any dichromate, and if you experience a problem
solutions.
(burning, coughing, difficulty breathing, vomiting,
♦♦ Always clean all utensils and equipment that have
been in contact with chemistry.
♦♦ Always keep your mixed chemistry in labeled and
sealed containers.
cramps, blurred vision, etc.), flush the problematic area with lots of water for 15 minutes and seek
immediate medical attention. If a dichromate spills
on your clothing, remove that article of clothing
and wash it well before putting it back on. Wear
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
♦♦ Never keep your chemistry in a location that will
gloves when working with this chemical. Be espe-
be accessible to children, pets, and guests. In other
cially careful around high-heat sources because this
words, do not store your chemistry in your home
chemical’s reaction to heat can be quite intense as it
refrigerator, whether it is labeled or not. If your
­decomposes.
chemistry needs to be refrigerated, buy a small
dorm-type unit for your lab and lock it.
Proper disposal of dichromate solutions is important.
As a rule, never throw loose and dry orange dichro-
♦♦ Always mix chemical formulas in the order that the
mate/bichromate crystals in the trash. Very small
components are listed. There are exceptions to this,
amounts of solution can be disposed of by dilution with
but those exceptions should be noted along with the
copious amounts of water and flushed away. Larger vol-
ingredients in the formulas.
umes of dichromate are a different matter. One method is
♦♦ Always have 911 or poison control numbers posted
in your lab.
♦♦ As an artist, your eyes are your life. You must have
an eyewash kit in your lab.
to add used developer to a dichromate solution. Another
is to make the solution alkaline by adding baking soda to
the solution. This change can be detected by using litmus
paper that will turn blue in a base or alkali. Once the solution is alkaline, pour it through several layers of coffee
filters. The liquid will be free of the chromium and then
X Note: Please be aware that all chemicals
flushing of the liquid can take place. The sludge in the
are hazardous in one form or another, and
coffee ­filters must be disposed of by a hazardous waste
any concerns you may have regarding their
facility. Check with local college photo lab managers to
use and dangers can be found by a
­ ccessing
get the names of these facilities.
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CHEMI CAL AB S TR ACT S E RV I CE
­R EGI S TRY (CAS )
Alcohol (Everclear)
The numbers following each chemical’s name are
brand grain alcohol can be purchased over the
part of a worldwide indexing system called Chemical
Internet (http://www.shoppersvineyard.com). It can
Abstracts Services Registry (CAS). It is used here to
also be purchased in liquor stores in several states
ensure that everyone using a chemical is dealing with
including New Mexico, where it is often included in a
the same one when describing it for any purpose. The
wet plate collodion kit (as grain alcohol) from Bostick
CAS numbers for these, and other chemicals on Earth,
& Sullivan. Do not drink this alcoholic liquid
can be found at various sites that offer CAS numbers.
alone or as a pea-brained additive to a punch-
Acetic Acid CAS# 64-19-7
Acetic acid is a clear fluid and has a pungent ­vinegar-like
odor. It is used in 20%–28% dilutions for photographic
purposes, although a 33% solution is called for in calotype (stronger if the ambient temperature is hot). At
28% it is primarily used as a stop bath and is found in a
hardening fixer bath. It can also be used as a solvent of
gelatin and collodion. To prepare a photo-grade solution dilute 3 parts glacial acetic acid with 8 parts water.
A 5% variation is used to make pickles. I have heard
that a weak dilution is also used for treating sunburn,
cult to locate. It is not available in all states. Everclear
bowl at a party.
Alum (Ammonium Alum, Ammonia
­Aluminum sulphate) CAS# 7784-26-1
This component is often found as a hardener for ­fixing
baths and gelatin, hypo-alum toner, and clearing
baths. Its fumes will cause distress to your respiratory
and intestinal tract, and contact will cause itching and
reddening to your skin. If it is ingested, do not induce
vomiting. Take normal safety precautions with gloves,
goggles, and a respirator.
Ammonia CAS# 7664-41-7
but I wouldn’t recommend this idea without medical
Ammonia is a corrosive gaseous fluid that can cause
advice. In high concentrations, both its vapors and
severe burning reactions to the respiratory system,
solution are corrosive and unpleasant for the skin and
eyes, and tissue. It is normally used in solution as
respiratory system. In low concentrations it will make
ammonium hydroxide. High degrees of exposure can
your eyes sting and may cause an allergic reaction on
cause fatal reactions, including death. Be ­
cautious
your skin. Vinegar is a 5% acetic acid. If you spill acetic
when using this chemical. There is a very strong
acid on your skin, wash well with clean water. Do not
odor associated with it, and a dual-filter respirator is
drink acetic acid at any level stronger than vinegar. If
advised. Be especially careful of getting this chemical
somehow you ingest a strong concentration, take milk
in your eyes because even the slightest amount will
of magnesia and seek medical attention. Acetic acid is
cause severe problems—even with immediate first aid
incompatible with strong oxidizers (meaning that it
treatment and wash.
will generate heat), carbonates, hydroxides, and strong
alkalis (a violent reaction). Never expose acetic acid to
X Note:
sodium peroxide or nitric acid because it may produce
nitrate or gold because it forms explosive azides.
Never mix ammonia with silver
an explosion. Dilute this chemical well before disposing. Store it above 63˚F to prevent it from solidifying.
X Note:
Ammonium Carbonate CAS # 506-87-6
This chemical presents itself as a fine, white crystal
Glacial acetic acid refers to a very
with a hint of ammonia in its odor. It is found most
strong concentrated acetic acid, usually between
often as an accelerator in warm-tone developers
80% and 99%, with a pH of 2.4. At this concentra-
and is not particularly dangerous. Vapors may cause
tion it is highly corrosive and is a severe poison.
respiratory distress, and contact with eyes, mucous
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
CHEMI CALS
Grain alcohol (95% 190-proof ethanol) can be diffi-
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tion. It should be kept at a good distance from acids
Ammonium Ferric Oxalate
CAS# 14221-47-7
and strong alkalis. Use normal safety precautions.
(Ammonium iron (III) oxalate trihydrate)
­membranes, and skin will result in redness and irrita-
Ammonium Chloride (Sal-Ammoniac)
CAS# 12125-02-9
Like all oxalates, this chemical will be toxic to your
health and highly corrosive to skin, eyes, tissue, and
respiratory system. This chemical can be absorbed
Ammonium chloride is a white crystal/powder used
in the body by breathing or ingesting and can cause
as an accelerator in sodium thiosulphate fixing baths.
havoc with your kidneys. Be very careful around any
It is also employed in salted albumen papers. This
oxalate. Wear nitrile gloves, a dual-filter respirator,
chemical is troublesome for the eyes and your respira-
and safety glasses. Also, never work with any oxa-
tory system. It is important to know that heating this
late without adequate ventilation. Do not breath
chemical will cause a wispy smoke that is very unpleas-
the fumes of any oxalate because its fumes can be
ant (hydrochloric acid and ammonia). Ammonium
absorbed through the lungs. If you spill an oxa-
­chloride will cause respiratory distress if inhaled. It
late on your clothing, forget modesty; remove your
is not compatible with acid concentrates, potassium
clothing and wash well with plenty of water. Do not
chlorate, and ammonium nitrate. Wear a respirator,
mix any oxalate with a strong concentrated acid or
safety glasses, and gloves when mixing.
oxidizer, and do not dispose of it in any place but a
hazardous waste facility. Most college photography
Ammonium Citrate CAS# 12125-02-9
labs have contracts with chemical disposal services,
This chemical is a moderately safe one to work with.
and you should contact them for assistance if you
Inhalation of the powder will cause respiratory distress
need to get rid of dangerous chemistry.
and is particularly problematic if it gets into your eyes,
or rub this chemical on your skin. If you experience a bad
Ammonium Hydroxide (30% Ammonia)
CAS#1336-21-6
reaction to ammonium citrate on your skin or in your
This chemical, also known as ammonia water, is
eyes, flush well with water and seek medical attention.
often found in developing and toning solutions as
causing redness and pain. Be careful not to inhale, ingest,
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
an a
­ ccelerator. Essentially, it is an aggressive form
Ammonium Dichromate (also Bichromate)CAS# 7789-09-5
of ammonia and water used in the mordançage pro-
This chemical is used in sensitizers for a number of
ammonia. Always work with good ventilation and
non-silver and alternative processes (gum bichromate
wear gloves.
and carbon printing) and behaves in much the same
cess. A 5% solution is the equivalent of household
manner as potassium dichromate except that it is more
Ammonium Thiocyanate CAS # 1762-95-4
aggressive and becomes saturated at 25% versus 13%.
Also
Potassium dichromate is preferred for gum bichro-
­ammonium thiocyanate is a component of gold-thio-
mate printing, as it renders more slowly and with
cyanate ­toning in POP and appears as a colorless, del-
less contrast. Its crystals are orange in color and are
iquescent ­(readily absorbs water) crystal with a slight
a strong irritant for literally every part of your being.
odor of ammonia. It is incompatible with chlorates,
It can cause ulcerations on the skin and, if inhaled,
oxidizing agents, ­peroxides, and strong acids, with
significant respiratory distress—especially in mucous
which contact will liberate a toxic hydrogen cyanide.
membranes. Ammonium dichromate is flammable in
Inhalation will cause respiratory distress, and all nor-
a dry state, so do not throw out the powder with the
mal safety precautions should be adhered to when
trash . . . over-saturate and flush for disposal.
using the chemical.
known
as
ammonium
sulphocyanide,
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Ammonium Thiosulphate (Rapid Fixer)
CAS# 1183-18-8
Ziatype process (for the brown coloration). This chem-
This chemical, when substituted for sodium thiosulphate,
to the skin, eyes, and respiratory system. Seek medical
rapid fixer). In terms of fixing speed, it is much faster
attention if physical distress accompanies its use.
in the wet plate collodion process and is preferred if you
Chrome Alum (Potassium Sulphate)
CAS# 7778-99-0
are anxious about working with potassium cyanide as
Chrome alum appears as a deep red/purple granule and
your fixer. It will take a few additional minutes to fix your
has no odor. It is sometimes employed as a ­hardening
plate versus using KCN, and the wash time is significantly
agent for gelatin and has a moderate health risk asso-
longer for the plates, but it is safer. Ammonium thiosul-
ciated with its use. It is incompatible with aluminum
phate is a colorless crystalline salt with strong fixer-like
and magnesium and will cause respiratory ­distress if
odor. Extended contact, as all photographers know, will
inhaled. Do not touch your skin, eyes, or mucous mem-
cause skin irritations. Decomposition or heating of this
branes while using it, and flush any infected area with
chemical will release a highly toxic sulphur dioxide gas.
copious amounts of water. Seek medical attention if
Keep it away from cyanotype chemistry. Use tongs when
symptoms persist.
than sodium thiosulphate. It can be used easily as a fixer
working with this chemical, and wear gloves and a respirator when mixing.
Citric Acid (2-hydroxypropane)
CAS# 77-92-9
Borax (Sodium Tetraborate)
CAS# 1303-96-4
Since we use a great deal of this chemical in alternative
This is powdered laundry soap. Employed as a laun-
others. Citric acid is very useful as a first rinse bath
dering agent, borax is the same chemical you will find
in the supermarket. It is often used as a weak alkali
accelerator in developers and in some hardening fixing
baths. It is also used to make a gold toner more alkaline and allows for a faster rate of gold deposit. Its use
has a moderate health risk, and normal safety precautions should be adhered to when using it. If you ingest
or breathe large quantities of it, wash the exposed area
well and seek medical attention if symptoms persist
(e.g., difficulty breathing, irritation, muscular spasms,
process work I have a little more to say about it than
in iron processes in that it lessens the chance of your
print developing iron stains. EDTA performs a similar chore as a chelate. Citric acid is the most common
food acidulant, an acid combined with a food product
to flavor or preserve. It is abundant in unhealthy snack
foods. This acid was initially extracted from lemons or
other citrus fruit, but today it is manufactured through
a sucrose fermentation technique and is recovered
by precipitation, evaporation, or crystallization. It is
available in two forms—monohydrate or anhydrous
itching, or pain).
(approximately 8.6% moisture)—and is sometimes
Boric Acid CAS# 10043-35-3
mentation is identical to organic citric acid.
This chemical is used in hardening fixers containing potash alum and acetic acid. It extends the life of
fixers and can be found in some buffered fine-grain
­developers.
Cesium Chloropalladite
available as a solution. The product obtained by ferWe work with citric acid in a white powder form,
and it is colorless upon dilution. It is also odorless with
a strong acidic flavor. One gram is soluble in 0.5 ml
water. The pH of a 1% solution of the monohydrate is
2.3, and the pH of a 1% solution of the anhydrous form
is 2.2. The Food and Drug Administration recognizes
citric acid as safe.
Cesium is a double salt built on an alkaline metal
Citric acid aids in the preservation of texture, color,
­compound. It sits at the lower end of Group 1 on the
aroma, and vitamin content of food products and is
periodic table and is a very heavy metal used in the
particularly useful as a chelant. It is the preferred
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
is used as a fixing salt in many high-speed fixers (e.g.,
ical, found in certain non-silver processes, is an irritant
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acidulant to ensure optimum gel formation in pectin
and presents a significant health hazard if used casu-
products. This chemical is commonly used in ton-
ally. Avoid light, air, and moisture in storage. Toxic
ers, as a clearing bath for some alternative processes,
fumes are harmful if breathed, and its dust must be
and it is one of the alternatives to hydrochloric acid in
avoided. Always wear a dual-filter respirator, gloves,
platinum/palladium clearing. Citric acid is also used to
and goggles when mixing or using. Copper chloride
transfer photomechanical ink images, (Rauschenberg
is incompatible with potassium, sodium, oxidizers,
used it) via saturation and rubbing the image on a
and strong acids that may result in the release of toxic
clean piece of paper from the rear of the saturated
chloride vapors. Overexposure will result in a host of
paper. It is not dangerous to work with but can cause
problems, including respiratory distress, chills, burn-
irritations to eyes, skin, and the respiratory system if
ing sensations in the intestinal tract, headache, and so
handled in a cavalier manner. However, do not mix cit-
on. Be very careful when using this chemical, and seek
ric acid with metallic nitrates because the reaction may
immediate medical attention if in distress.
be explosive. It is also incompatible with carbonates,
copper, aluminum, and zinc.
Collodion USP CAS# 99994-22-6
Copper Nitrate CAS# 10402-29-6
Be careful around this chemical because it is harmful
to your body. Prolonged or intense contact will cause
Collodion is a viscous fluid that is used in ­photographic
chills, gastrointestinal problems, and pain. Avoid con-
practice as a salted binder for sensitizing wet plate,
tact with the skin, breathing, or ingestion. Irritations
ferrotype, and ambrotype glass plates. It is not
­
of many sorts, and burns, are common if precaution is
particularly dangerous but is very flammable, and
­
not taken in the use of this chemical. Like all nitrates,
­precautions should be made when working with the
you must be vigilant when using it and adhere to all
material. Although it is possible to make c­ollodion
safety precautions: gloves, goggles, and a respirator.
at home with nitrated cotton, ether, and alcohol,
Seek immediate medical attention if in distress.
I strongly advise that you do not do so. Instead,
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
­purchase a prepared plain collodion.
When using collodion be sure to have adequate
Copper Sulphate CAS# 7758-98-7
Copper sulphate appears as a blue/translucent ­crystal
ventilation, wear gloves, and wear a respirator if
­
or powder. This chemical is used in toners (copper),
­airborne concentrations are high. Collodion vapors can
bleaches, and intensifiers. Not a great deal is known
exist quite a distance from the actual material, and you
about this chemical other than it is a ­moderately toxic
must be sure that any ignition source is off before use.
one and all precautions should be taken in its use
Keep the collodion away from strong acids and oxidizers
and handling. Wear gloves and a respirator for mix-
and take general lab safety precautions when using it.
ing or prolonged use, and do not touch your eyes or
When you wish to dispose of unused collodion,
mouth when using it. Copper sulphate is an irritant.
spread some newspapers outside in a non-windy
The usual routes by which humans can receive toxic
place (I use a wheelbarrow in the garage) and pour
exposure to copper sulphate are through eye or skin
out thin layers of the collodion on the newspaper. It
contact, as well as by inhaling powders and dusts. Skin
dries quickly as a thin skin. Repeat the step until your
contact may result in itching or eczema. Eye contact
collodion is gone and then clean your container with
Everclear alcohol (190 proof). Do not use the newspaper to start a campfire, as it will be explosive.
Copper Chloride CAS # 10125-13-0
with copper sulphate can cause conjunctivitis, inflammation of the eyelid lining, ulceration, and clouding
of the cornea. Upon oral exposure, copper sulphate is
only moderately toxic. According to studies, the lowest dose of copper sulphate that had a toxic impact on
Copper chloride appears as a blue/green crystal and
humans was 11 mg/kg. Because of its irritating effect
is used in many toners, bleaches (mordançage), and
on the ­gastrointestinal tract, vomiting is automatically
intensifiers. This chemical is a strong oxidizing agent
­triggered upon ingestion of copper sulphate.
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and is commonly found as a preservative in some foods
and in agricultural uses. It may irritate the skin, eyes,
chemical formula CuSO4. This salt exists as a series
and respiratory system. EDTA is generally purchased
of compounds that differ in their degree of hydra-
in a white crystal form and can cause minor problems
tion. The anhydrous form is a pale green or gray-white
if you are too casual when using it.
powder, whereas the pentahydrate (CuSO4·5H2O),
EDTA is commonly found as a preservative in pro-
the most commonly encountered salt, is bright blue.
cessed foods, in cosmetics to improve stability, as a
CuSO4·5H2O is a shade of blue and is very toxic to
detergent in the dairy industry to clean bottles, as a
the environment and is irritating to the eyes and
treatment for mercury poisoning, and in soft drinks
skin. It can be harmful if swallowed. Other names for
containing ascorbic acid and sodium benzoate (most
copper(II) sulphate are “blue vitriol” and “bluestone.”
all of them) to reduce the formation of the carcinogenic
Copper sulphate is a commonly included chemical
benzene. It can also be used in the recovery of used lead
in children’s chemistry sets and is often used to grow
acid batteries and is found in cleaning compounds,
crystals in schools and in copper plating experiments.
detergents, and in photography as an oxidizing agent.
Copper sulphate is also used to test blood for anemia.
For most of the twentieth century, chromated cop-
Ferric Ammonium CitrateCAS# 1185-57-5
per arsenate (CCA) was the dominant type of wood
Ferric ammonium citrate is also known as iron
preservation for uses other than deep driven piles, utility poles, and railroad ties. It gives the treated wood
a peculiar green coloration. To make pressure-treated
wood, a large cylinder is filled with an aqueous chemical bath. Copper sulphate pentahydrate is dissolved in
the water along with other additives prior to the lumber being placed inside the cylinder. When the cylinder is pressurized, the chemicals are absorbed by the
wood, giving the wood fungicidal, insecticidal, and
UV-light-reflecting properties that help preserve it.
EDTA
ammonium citrate, ammonium ferric citrate, iron
­
citrate, and ammonium iron (III) citrate. It presents
itself as a green, or brown, scale crystal/powder, has
a somewhat undetermined structure, and is prepared
by treating ferric hydroxide with hydrated citric acid
(75%), iron (16%), and ammonia (7.5%). This chemical is commonly found in human-ingested iron supplements, cyanotype formulas, iron toners, and other
non-silver formulas, and it functions as a sensitizer. It
is not particularly toxic, but you must still exercise care
in its handling, storage, and use. It may be the cause
of eye and skin irritations if precautions are ignored.
Disodium EDTA (Disodium Salt
­Dihydrate) CAS# 6381-92-6
If you notice that your urine is pink, then you have
Also known as ethylenediamine tetraacetic acid and
should seek medical attention.
absorbed or inhaled far too much of this stuff and you
disodium salt. It is used as a first clearing bath for Pt/
Pd. It may irritate the skin, eyes, and respiratory sys-
Ferric Citrate CAS # 2338-05-8
tem. This chemical is more of an irritant than a danger
Ferric citrate is a brownish red powder in a 17% iron
and should be handled in a similar manner as its sibling,
state. There is a purified variation of this chemical, but
tetrasodium EDTA.
it is not what you are looking for in alt pro work. Ferric
Tetrasodium EDTA (Tetrasodium Salt
Dihydrate) CAS# 10378-23-1
citrate is light sensitive and is used, for our ­purposes,
primarily as an ingredient in preparing a Van Dyke Part
C contrast control alternative to be mixed with the tradi-
Repeat after me . . . ethylenediamine tetraacetic acid
tional Van Dyke Part C. See the Van Dyke ­chapter. It is
tetrasodium salt dihydrate is a chemical recently
not particularly toxic, but you must still exercise care in
employed as an alternative to hydrochloric or citric
its handling, storage, and use. It may be the cause of eye
acid in some clearing baths. It is relatively safe to use
and skin irritations if precautions are ignored.
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
Copper(II) sulphate, also known as cupric sulphate
or copper sulphate, is a chemical compound with the
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Ferric Oxalate (Ferric Ammonium
­Oxalate) CAS # 2944-67-4
and preservative in photography. Formalin is used
Platinum and kallitype printers use ferric oxalate as
bichromate and other processes in which sizing/
the light-sensitive ingredient in their sensitizers. It is
an oxalic acid salt and is toxic. The body can deal with
it in small quantities. Ferric oxalate is a weakly bound
chemical and will quickly decay to ferrous oxalate and
then to oxalic acid and ferric oxide (rust). Please see
the potassium oxalate entry for more information.
Ferric oxalate is a green/transparent crystal and is
light sensitive. All oxalates are toxic, and you should avoid
breathing, touching, or ingesting them. They are corrosive to all parts of your body and can cause ulcerations
on the skin. Severe kidney damage can be the result of
large amounts of absorption or breathing fumes. Wear
latex or nitrile gloves, a respirator, and eye protection
when working with oxalates. If you happen to spill ferric
oxalate on your skin, wash it well with clean water. If you
spill it on your clothing, remove that clothing and wash
it well. If it is ingested, call a doctor and poison control.
Be extra cautious when using any oxalate because it is a
most serious health hazard if used in a casual manner.
EDTA is a chelate that will dissolve ferric oxalate . . .
as a tanning and hardening agent of gelatin in gum
hardening is required. This chemical is highly toxic
and unhealthy to the body if safety precautions are
not used. Do not breathe the fumes (which are very
strong) and work only in very well-ventilated environments, such as outdoors with the wind at your
back. Be cautious of formalin-prepared papers
indoors, after they are dry, because they will continue to outgas for a day or so and be dangerous to
your respiratory system. Fumes from formalin will
attack the mucous membranes of your eyes, nose,
and throat. This chemical is a carcinogen and you
must take it very seriously. If somehow this chemical
is ingested, seek immediate medical attention: you
will see the following . . . coughing and respiratory
distress that persists, violent vomiting, headache,
severe abdominal pain, weak pulse, burns, blurred
vision, and sudden change in skin color to white. In
other words, take this seriously.
See glyoxal below.
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
an important thing to know when you need to use it as
Fumed Silica
a clearing bath.
Fumed silica (not to be confused with silica fume)
is amorphous (meaning it has undefined shape and
Ferrous Sulphate CAS# 7782-63-0
This chemical is used in standard wet plate ­collodion
developers. It is also used in stain removing and
­clearing baths. If you have taken in too much of this
chemical through breathing, touching, or tasting, you
will have an acidic and sour taste in your mouth. It
does not keep well in solution. This chemical can cause
itching, burning in the eyes, breathing difficulty, and
general ill health. Be diligent in its use and follow all
safety precautions. Seek immediate medical attention if you find yourself in discomfort or distress when
using this chemical.
Formalin/Formaldehyde CAS# 50-00-0
form), rather than crystalline, and is a vaporized form
of clear solid silica that behaves as if it were a liquid.
Fumed silica is made by flame hydrolysis of silicon
tetrachloride. Silicon tetrachloride is a liquid at room
temperature. It is vaporized and then passed through
a fuel/air flame at an extreme temperature to produce fumed silica. Fumed silica is essentially a harmless, non-carcinogen that is a primary thickening
ingredient in fast-food milkshakes and is used as an
anti-caking agent in powders, an abrasion resister in
concrete, and in kitty litter. It also features light-diffusing properties, which is one of the reasons the dark
end of the tonal scale looks so nice in an alt pro print
that employs it as a pre-coating. It is also found in
cosmetics like lipstick and toothpaste. When applying
Formalin/formaldehyde, a 37% concentration of
it with a hot-dog roller as a pre-coating to a process
­formaldehyde gas in water with an additional com-
on paper, it would be prudent to wear eye protection
ponent of methyl alcohol, is employed as a ­hardener
and a respirator.
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Gallic Acid CAS # 149-91-7
­significant skin and respiratory allergies if you are
Gallic acid appears as a white/pale yellow crystal and is
casual with it. Pay heed to all normal precautions
tional chemical in calotype development and developing-
when using this chemical.
out formulas for processes such as the whey technique. It
Gum Arabic CAS# 9000-01-5
does not present a significant health hazard but is incom-
Gum arabic, or gum acacia, can be traced back to 2650
patible with ferric salts, silver salts, alkalis, ammonia,
BCE, when it was harvested from the sap of various
chlorates, and strong oxidizing agents. Overexposure will
species of acacia trees in Nigeria, Cameroon, Chad,
cause moderate discomfort and should be treated with
Mali, and the Sudan. The acacia trees grow primar-
respect regardless of its low toxicity.
ily in the sub-Saharan (Sahel) areas of Africa, and the
Sudanese variety is considered the premium grade.
Glyoxal CAS# 107-22-2
This chemical is recommended as a substitute for
formalin/formaldehyde as a hardening agent for
­
­gelatin in sizing for the gum bichromate process. It
is an alternative, in terms of reactivity and toxicity, to
­formalin, but insufficient evidence has been offered
by the scientific community to allow you to treat it
In gum printing, the dichromate is added to the gum
to create the liquid foundation of the gum sensitizer.
Gum arabic comes in a variety of grades (tints) from
colorless to dark brown. On exposure to light, the gum
and the ammonium dichromate solution will harden in
proportion to the exposure of UV light.
casually. Glyoxal should never be mixed with sodium
Hydrogen Peroxide (3%) CAS# 7722-84-1
hydroxide or nitric acid, and if heated in an enclosed
Hydrogen peroxide is a colorless and not very ­stable
container, it is explosive. It is also corrosive to all
­liquid used primarily as a bleaching agent, an ­antiseptic,
metals. Glyoxal should be used in well-ventilated
­
or an oxidizing accelerator in the cyanotype process.
environments (such as outdoors), and all precau-
You do not have to be enormously ­concerned with this
tions should be taken to prevent ingestion, contact
chemical when purchased in its 3% ­over-the-counter
with the skin, and breathing of its fumes. Note: Just
form. In dentistry applications it is often mixed with
because glyoxal doesn’t have an offensive odor like
water and used to clean wounds inside the mouth.
­formaldehyde, doesn’t indicate that it is safer and
In this concentration, which we are most ­accustomed
that you can relax using it. Treat ­glyoxal with the
to as a treatment for cuts and ­abrasions, hydrogen per-
same respect you would formalin. After sizing your
oxide is a simple peroxide and an ­oxidizer . . . which is
gum paper with gelatin and glyoxal, hang it to dry in
what is happening when you pour it on an active wound
well-ventilated space outside of your living area. It
and it generates a white ­effervescent foam. Hydrogen
requires an off-gas period of 24 hours. Once dried,
peroxide is used in alternative processes as an oxidizer
label each sheet as glyoxal sized and store the sized
for the iron in cyanotypes (the WOW factor effect) when
paper in a zip lock bag.
prepared in a very dilute bath for a finished cyanotype,
resulting in a very deep and beautiful blue.
Gold Chloride CAS# 16903-35-8
Gold chloride is also known as chloroauric acid,
gold trichloride acid, and hydrogen tetrachloroaurate (III). Gold chloride is generally used in dilutions of 1%, 5%, and 8% for purposes of toning in
Hydrogen peroxide is also used to neutralize potassium cyanide (KCN) wet collodion fixer by converting
it to a safe, and unregulated, potassium cyanate. See
the instructions in the Wet Collodion chapter.
a number of ­processes. Gold chloride is also a pri-
Hydrogen Peroxide (28%–33%)
mary component in Ziatype printing and will raise
In this strong concentration, hydrogen peroxide
the contrast of the print when added to the formula.
is used primarily for mordançage bleaching and
Gold chloride is a strong irritant and can cause
in beauty parlors to alter hair color. It is a health
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
used as a component in cyanotype toning and as a tradi-
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the fumes, and flush exposed areas well with water
Lithium Palladium Chloride/Lithium
Chloropalladite
if you experience problems after contact. If you work
Lithium palladium chloride/lithium chloropalladite
­hazard. Wear appropriate protection, do not breathe
in a beauty salon, please wear appropriate protective clothing, gloves, and breathing apparatus . . . this
stuff is not good for you and may, under some circumstances, lead to pulmonary edema . . . also known
as high-altitude sickness, in which fluid accumulates
in the lungs.
Hydrogen Tetrachloroaurate(III) Trihydrate
CAS# 27988-77-8
Used in the sensitizer for chrysotype—version S.
Also known as gold(III) chloride hydrate and hydochloroauric acid. In early literature it was called
gold chloride. This chemical is corrosive and can
be destructive to your mucous membranes. Take
appropriate safety and working measures when
using it.
Kodak Hypo Clearing Bath
This solution is used to accelerate the neutralization
of fixer and therefore cut the wash times for films and
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
papers. Two formulas for hypo clearing baths are the
following.
Formula #1: 750 ml water, 200 g sodium sulphite
(anhydrous), 50 g sodium bisulphite, and water to
make 1 liter.
Formula #2: 125 ml hydrogen peroxide, 10 ml
ammonia solution, and water to make 1 liter.
Other formulas include sodium sulphite, EDTA,
sodium citrate, and sodium metabisulphite. Hypo
­clearing agents can be mild irritants to the body in
­concentrated solutions for lengthy exposure.
Lead Acetate CAS# 301-04-2
This chemical is used as a toner. Lead acetate is a
is a double salt built on an alkaline metal compound
(lithium), which is a lightweight alkali sitting atop the
periodic table. It is used in the Ziatype process and
results in a cool black value. Do not drink it or play
with it. Lithium is a primary component in medicating
bipolar disorder, and high incidences of exposure can
have adverse effects on the nervous system.
Mercuric Chloride CAS# 7487-94-7
Also known as mercury(II) chloride, mercuric c­ hloride
was used as a photographic intensifier to produce
positive pictures in the collodion process of the 1800s.
When applied to a negative, the mercury(II) chloride
whitens and thickens the image, thereby increasing the
opacity of the shadows and creating the illusion of a
positive image (Towler, 1864).
Mercuric chloride is toxic, white, and a soluble salt
of mercury (at 6%). It has been used in disinfectants,
as a fungicide, as a treatment for syphilis before antibiotics, and in photographic fixers. It’s also odorless and
really dangerous, which is why I’m letting you know
about it here. Take all safety precautions when working with this chemical.
Methyl Alcohol (Wood Spirit) CAS# 67-56-1
This is a poison. It can be readily absorbed by ­breathing
and through the skin and is considered very dangerous to
the central nervous system. It can cause blindness. Use all
safety precautions against exposure when using methyl
alcohol. If methyl alcohol is swallowed, administer an
emetic (a medicine that induces vomiting) and bicarbonate of soda (1 tsp in a cup of water), and call a doctor.
is toxic. It can be a problem for your body and can
Muriatic Acid (Hydrochloric Acid) CAS # 7647-01-0
be absorbed by breathing its fumes. It is a poison
Muriatic, or hydrochloric, acid is a clear, colorless,
if ingested and can cause brain damage. Fumes are
irritating, vaporous poison that was used as a p
­ rimary
possible carcinogen, and like other lead products,
­
released when it is heated. Be cautious in all safety
clearing bath with Pt/Pd and as a tray cleaner . . .
respects when using this chemical.
among other uses. It can be purchased at hardware
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stores and pool supplies and is often used by masons
which may result in kidney damage. It is incompatible
for cleaning bricks. Be respectful of this chemical and
with alkalis, silver, and oxidizing agents. Take normal
take precautions while using it.
safety precautions when using this chemical.
Take all necessary precautions when using oxalic
Nitric acid is a colorless liquid and will make its appearance known as soon as you unscrew the top to its bottle; a chemical vaporous smoke will appear like an evil
genie from the bottle. It is used in some ­cyanotype toning formulas, as a preservative in Pyro developers, and
as a component in bleach. Nitric acid is highly corrosive to most anything it comes in contact with, including your body. At present, there is really no safe way
to use this chemical in regard to ventilation except for
with a professional chemical hood. Nitric acid is a very
aggressive oxidizer and will react violently with a vast
acid because it is toxic. Its primary role in your life
is likely to be as a cleaning and bleaching agent . . .
especially for the removal of rust/iron deposits. In
­
alternative processes, oxalic acid is also used as a
reducing agent in the platinum/palladium process.
The principle toxicity risk when using oxalic acid is
due to kidney failure, which may cause precipitation
of solid calcium oxalate, the main ingredient of kidney
stones. That said, wear nitrile or safety examination
gloves and eyewear when using this chemical.
Palladium Chloride CAS# 7647-10-1
range of metals, acids, solvents, and other things found
Palladium chloride is dark brown and without odor.
in the lab or home. Although I like using it in cyano-
This chemical is found primarily in palladium ­printing
type toning I am not sure if the resulting color is actu-
and in certain other non-silver processes and is an
ally worth the risk. If you are a teacher, you mix the
irritant to the skin, eyes, and respiratory system.
formula. Also, be careful of the cap on the glass bottle
Palladium chloride is moderately toxic. It is often asso-
that the acid is stored in. If it is an old fashioned plastic
ciated with bipolar disorder medication. High doses
cap there is a good chance that the acid will destroy
can cause problems with central nervous system func-
the cap’s integrity in time. Be hyper-careful in its use
tions. Be cautious of contact with the skin, ingestion,
and storage. If this chemical is spilled on skin, wipe
and breathing fumes. Use normal precautions in its
off what you can, immerse the relevant skin areas in
use and handling.
water, and then cover the area with a paste of water
and baking soda. Go to a hospital and seek immedi-
Potassium Bromide CAS# 7758-02-3
ate medical attention. If you spill it on your clothing,
Potassium bromide appears as white crystal and
forget modesty and immediately remove your clothes.
is without odor. This chemical is often used as a
If nitric acid is ever swallowed, ­administer a small
restrainer in bleachers and developers. It is also widely
amount of soap softened in water, milk, or raw egg.
used in intensification, reducing, t­oning, and many
You can also force the patient to drink a small amount
other photographic formulas. It is mildly ­
irritating
of magnesia or plaster softened in water. Seek medical
to the tissues of your body and can sometimes cause
assistance for extreme exposure.
skin problems. It is a mutagen, and extreme exposures
can result in depression of the central nervous system.
Oxalic Acid (Ethanedioic Acid) CAS# 144-62-7
Oxalic acid is translucent and odorless. This chemical is
Potassium bromide is incompatible with strong oxidizers and acids. Use all safety ­precautions.
formulas. It is found in all leafy green vegetables but is
Potassium Chloroplatinite CAS# 10025-99-7
highly toxic in strong concentrations so you must use all
This chemical is found in toners and intensifiers, and
safety precautions in its use and storage. Oxalic acid is
it is the primary ingredient in platinum printing. It
corrosive to tissue and removes calcium from the blood,
is highly corrosive to human tissue and can cause
used in blue toners and as a preservative in certain Pyro
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
Nitric Acid CAS# 7679-37-2
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severely adverse reactions to extreme or long-term
Potassium Dichromate CAS# 7778-50-9
exposure. This chemical is a poison and should be used
Potassium dichromate (bichromate) is a beautiful
and handled with all safety precautions.
orange crystal that is used as a principal sensitizer
in the gum bichromate processes and as a contrast
Potassium Cyanide CAS# 151-50-8
boost additive in many non-silver processes. It is also
Potassium cyanide (KCN) is a white granular,
a bleaching agent. It is most often used as a ­saturated
odorless crystal, much like sugar, and is also
­
solution or diluted for use as a contrast additive to
known as hydro/potassium salt of hydrocyanic
wash-development baths or sensitizer. It is highly
acid. Highly toxic, a health hazard, and Level III,
toxic, corrosive, and can enter the body through
KCN is odorless, but due to hydrolysis, solids emit
absorption, ingestion, and breathing. It can cause
small amounts of hydrogen cyanide, which smells
extreme allergic reactions and is a powerful irritant
like bitter almonds. KCN is highly soluble in water
to human tissues and internal systems. It is a carcino-
and is actively employed in, as well as a preferred
gen and must be handled with care. It is incompatible
­chemical for, fixing wet plate collodion due to its
with any combustible, organic, or oxidizable mate-
­ability to lend brightness to the plates, longevity,
rial. It is extremely destructive to tissue and respira-
and ­coffee and cream highlight coloration in tin-
tory systems and may cause distress. If this chemical
types and ­ambrotypes and because washing times
is spilled on clothing, remove the clothing immedi-
for the plates are measured in seconds rather than
ately. Do not be the least bit casual when using this
minutes . . . which is useful if making plates on a
chemical, and seek immediate medical attention if
battlefield or if you are backpacking and can’t take
you experience discomfort in breathing, burning, or
along a lot of water. KCN is extremely dangerous
dizziness.
and must never be placed in a situation where it can
come into contact with an acid . . . thus creating a
(See Ammonium Dichromate for safety and
­disposal.)
lethal hydrogen cyanide gas.
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
Exposure to potassium cyanide can be rapidly
Potassium Ferricyanide CAS# 13746-66-2
fatal. It has whole-body (systemic) effects, particularly
Potassium ferricyanide is an orange-red crystal and
affecting those organ systems most sensitive to low
has no odor. It is also called red prussiate of potash
oxygen levels: the central nervous system (brain), the
and is used in reducers, bleaches, toners, and many
cardiovascular system (heart and blood vessels), and
alternative and non-silver processes, specifically
the pulmonary system (lungs).
iron based. Ruby red in color, potassium ferricyanide is a low-­toxicity-level chemical. It is the Part A
X Note:
To neutralize a 1.2% potassium
(bleaching agent) of sepia toner and is one of the
cyanide fixer solution (standard dilution for
­
primary ingredients in cyanotype. Potassium ferri-
wet plate collodion), put on eye protection, a
cyanide is poisonous in high concentrations. Take
respirator, and nitrile gloves and place potas-
all necessary precautions in its use and handling.
sium cyanide in an empty and clean drywall
Do not expose it to acids, because it may release a
bucket or large glass beaker. Slowly add 600 ml
cyanide gas (hydrocyanic acid). If potassium ferri-
of drugstore-grade 3% hydrogen peroxide to a
cyanide is swallowed, administer a tablespoon of 3%
liter of used potassium cyanide. In a short time
hydrogen peroxide. Have the patient inhale ammo-
you will have converted a heavily regulated
nia fumes, provide artificial respiration if necessary,
chemical to a non-hazardous, un-regulated
and call a doctor. Potassium ferricyanide is incom-
potassium cyanate.
patible with extreme heat and can release fumes of
cyanide and oxides of nitrogen. It is also incompat-
Please read the section on potassium cyanide in the
fixing section in the Wet Plate Collodion chapter.
ible with ammonia. Use standard safety precautions
when using this chemical.
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Potassium Iodide CAS# 7681-11-0
­attention if you experience distress when using it. Signs
Potassium iodide, also known as potassium salt, is
and symptoms of distress are nervousness, cramps,
the first stage of the calotype and is responsible, in
combination with silver nitrate, for the silver iodide
depression, corrosive action on the mucous membranes,
redness of the skin, blurred vision, burns, and pain.
but you should take normal safety precautions when
Potassium Sodium Tartrate (Rochelle Salt)
CAS# 304-59-6
using it. Avoid breathing, ingesting, or placing potas-
Potassium sodium tartrate is a double salt first
sium iodide in direct contact with your skin. If you get
­prepared in La Rochelle, France, in 1675. As a result the
any in your eyes or on your skin, flush the area with
salt is known as Rochelle salt and is used in ­alternative
clean water for 15 minutes. Seek medical attention if
processes in the kallitype. Rochelle salt can be made
irritation or a rash persists.
from common household goods: cream of tartar and
­compound. It is not a particularly hazardous chemical,
baking powder.
Potassium Metabisulphite CAS# 16731-55-8
Potassium Metabisulphite is a white crystalline
Pyrogallic Acid CAS# 87-66-1
­powder with a pungent sulphur odor. The main use of
This chemical is principally used as a high-octane
the chemical is as an antioxidant or chemical ­sterilant.
developer for pyromaniacs. It is a chemical used in
It is a sulphite and is chemically very similar to sodium
many alternative developers such as calotypes and
Metabisulphite, with which it is sometimes used
for processing film-based negatives for processes
­interchangeably. Potassium Metabisulphite is used as
such as Pt/Pd due to the tan coloration it gives the
a clearing agent in the gum bichromate process.
film stock during development. It enters the body
through absorption. It may cause respiratory and
Potassium Oxalate CAS# 583-52-8
gastrointestinal problems. Avoid the chemical’s dust
The oxalates are the only salts that are poisonous, but
or breathing its fumes. Use appropriate safety pre-
they are not always bad for you or the environment.
cautions.
Oxalic acid is commonly found in nature (e.g., in green
leafy vegetables) and is responsible for the bitter taste.
Silver Nitrate CAS# 7161-88-8
Too much of it is not good for you . . . 10 pounds of spin-
Silver nitrate appears as a colorless and odorless
ach in one sitting is a lethal dose of oxalic acid. In small
­crystal and discolors on exposure to light. Silver nitrate
quantities the human body deals with the ­oxalates quite
is highly corrosive. This chemical can cause severe skin
handily, as the body produces natural chelates that ren-
and eye problems and is particularly destructive to
der them harmless. The most commonly used developers
mucous membranes and the upper respiratory tract. It
such as ammonium citrate, potassium oxalate, sodium
is the primary silver salt found in photographic emul-
acetate, and sodium citrate are quite harmless and can be
sions, alternative processes (e.g., Van Dyke, salted
disposed of in a municipal sewage system if well diluted.
paper, kallitype, albumen, calotype, etc.), and intensi-
Potassium oxalate is transparent and odorless, and
fiers. Silver nitrate will discolor your skin, is a caustic
it is used in toners and as one of the developer options
substance, and may cause blindness if it gets into your
for platinum/palladium. Like all oxalates, this chemical
eyes. If you get silver nitrate on your skin, you may
in a concentrated form is toxic and corrosive to human
experience redness and an eventual henna-like brown
tissue. Unsafe exposure is foolhardy because this chemi-
stain that will last for several days. On exposure, wash
cal can cause significant problems for all parts of your
the area well with repeated rinses of water. Rubbing
body. It is incompatible with strong acids and oxidiz-
the area of exposure with sodium chloride (table salt)
ers. Use all safety precautions, including nitrile gloves,
will help lessen the damage to a degree and will help
a respirator, and safety glasses. Seek immediate medical
with stain removal.
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
a white, odorless chemical used as a salting agent in
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This is more serious . . . if you get silver nitrate in
in fixing baths and for removing stains from gum
your eyes, immediately flush with copious amounts
bichromate and POP processes. It can be substituted
of water, or saline solution, and continue doing so
for sodium Metabisulphite. It is a strong irritant to the
while medical attention is summoned. If you get a
respiratory system and can cause irritation to the skin,
bad silver nitrate stain on anything but your eyes,
eyes, and mucous tissue. Take normal safety precau-
you can eliminate the black stain by washing the
tions when using this chemical.
area with a solution of 2 teaspoons of sodium bisuldioxide gas that will be created by this act of cleans-
Sodium Carbonate (Anhydrous) CAS# 497-19-8
ing. If you happen to ingest silver nitrate you will
Sodium carbonate appears as a white, odorless
experience great distress, burning, shock, and coma.
granule. This chemical is also called soda ash and
­
Do not induce vomiting. Force feed strong salted
hydro-sodium and is used as a primary alkali accelera-
water concentrations.
tor in developers. It is also used in cyanotype toning
phite in a quart of water. Be cautious of the sulphur
Silver nitrate is a very strong oxidizer. It will ­combust
and works as a reducer and bleach on iron prints. It is
and explode if allowed to come into contact with any
an irritant to eyes, tissue, and the respiratory system.
ammonia compounds, such as ammonium hydroxide
Sodium ­carbonate can release a gas when mixed with
(the strong concentration of ammonia used in mordan-
acid, stop, or fixing baths. It reacts violently with acids,
çage). Never mix silver nitrate solutions with metals such
and caution should be taken. Kodak Balanced Alkali
as aluminum or zinc. Use extreme safety precautions
(Kodalk) can be used as a replacement for sodium
especially by wearing gloves, a respirator, and goggles or
­carbonate. Use with care regardless of the low risk.
safety glasses when working with this chemical.
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
Sodium Acetate CAS# 127-09-3
Sodium Chloride (Kosher Salt) CAS # 7647-14-5
Sodium acetate is the sodium salt of acetic acid. Its pH
Sodium chloride appears as a white, odorless crys-
rests between 7.5 and 9.5. It is an inexpensive chemical
tal and has a very low health risk associated with it.
produced in industrial quantities for a wide range of
It is primarily used in salting gelatin for albumen and
uses. As the conjugate base of acetic acid, it is a rel-
salted paper printing, as a fixing agent, as an additive
atively strong base. Sodium acetate is used as one of
to first rinse washes, and, when mixed with water, as
several developer options for platinum/palladium and
a wonderful substance to go scuba diving in. It is also
is not particularly toxic. Sodium acetate is often found
good to keep on hand in the lab for when you order
in toners such as gold and is employed as a buffer in
out for pizza. Note: Do not buy ordinary table salt and
acidic solutions. It should be used and handled with
think that it is pure sodium chloride. More than likely
respect. Use normal safety precautions.
it is loaded with additives. Buy kosher salt or sodium
Sodium Bisulphate CAS# 7681-38-1
Sodium bisulphate appears as a white crystal and is odor-
chloride from a chemical supply. Use caution not to
rub it in your eyes, and flush overexposed areas with
water to rinse them clean.
less. It is used as an acid rinse and in combination with
tion with sodium chloride to make a hydrochloric acid
Sodium Citrate (Tri-Sodium Citrate)
CAS# 68-04-2
substitute. It presents a low health risk, but normal safety
Add baking soda to citric acid and you’ll get sodium
precautions should be adhered to when using it.
citrate. Sodium citrate appears as a fine, white, ­odorless
acetic acid, as a stop bath. It can also be used in conjunc-
Sodium Bisulphite CAS# 7631-90-5
granule and is incompatible with strong ­oxidizers. A
common use of this chemical is as a primary ingredient
Sodium bisulphite is a coarse, white granule and has
in salted paper gelatin salted emulsion and ­kallitype
a strong odor of sulphur. It is used as a preservative
developer. This chemical has a low health risk but can
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cause mild irritations to the eyes, tissues, and respira-
Sodium Sulphite CAS# 7757-83-7
tory system. Sodium citrate is used in ice cream to keep
Sodium sulphite appears as a white, odorless crys-
ing agent. Sodium citrate attaches to calcium ions in
water. Compounds with similar functions are sodium
carbonate, EDTA, and phosphoric acid.
Sodium Gold Chloride CAS# 13874-02-7
tal. This chemical is extensively used in alternative
­process wet work as a clearing agent for albumen,
Ziatype, and chrysotype, as a preservative in many
developers, and as a clearing bath for some films
such as Polaroid Type 55 Positive/Negative. It is also
used as a primary ­component in fixing baths and
Sodium Palladium Chloride (see Potassium
presents a very mild health risk. It can be an irritant
Chloroplatinite)
to eyes and tissue and will release a sulphur diox-
This chemical can cause severe allergic reactions
ide gas if heated. Use general safety precautions in
and is an irritant to human tissue. Do not allow it to get
use and handling. It can be ­substituted for sodium
into contact with your skin, and do not ingest or breathe
­bisulphite.
its fumes. Use proper safety precautions at all times.
Sodium Potassium Tartrate CAS# 304-59-6
Sodium Tetraborate CAS# 1303-96-4
(See Borax)
Also known as rochelle salt. It is used in some t­oners
­kallitype. There are no health hazards associated with
Sodium Tetrachloroaurate(III) Dihydrate
CAS # 13874-02-7
this chemical.
This chemical is used in the Part B solution of the
and sensitizers and as a developing component in
Sodium Metabisulphite (Sodium
­Pyrosulphite) CAS # 7681-57-4
new chrysotype sensitizer formula and is also known
as sodium chloroaurate and sodium gold chloride. It
is very precious in regard to use with a gram cost in
Sodium Metabisulphite is sometimes referred to
excess of $82.00. It is corrosive and can be destructive
as ­disodium. It is used as a clearing aid in the gum
to your mucous membranes. Take appropriate precau-
bichromate process. It is often found in disinfec­
tions when working with this chemical, as it may also
tants, antioxidants, and preservatives. It may act as
cause allergic skin reactions.
an ­irritant to eyes and skin but is generally considered
safe. It can be substituted for sodium bisulphite in the
gum clearing stage if needed.
Sodium Selenite CAS# 10102-18-8
Sodium Thiosulphate (Hypo/Fixer) CAS# 7772-98-7
Sodium thiosulphate is a colorless and odorless crystal.
It is also known as sodium hyposulphate or “hypo” and
Sodium selenite is a white crystal salt solid that is solu-
is incorrectly referred to as hyposulphate of soda since
ble in water. It is very incompatible with strong acids
Herschel’s discovery of it in 1819. It is used in a vast
and mixing should be avoided. The chemical is toxic if
variety of dilutions depending upon what process you
ingested, inhaled, or absorbed through the skin. Wear
are using it for, and it is one of the very few substances
adequate safety gear when using this chemical. Sodium
that is capable of dissolving silver bromide. Contact
selenite is a primary ingredient in Kodak Rapid Selenium
with the skin is not dangerous, but it can decompose
Toner and will tone silver. If splashed, rinse well. If you
through the action of aging or heat and form a sulphur
splash the eyes, rinse for 15 minutes. If inhaled, get out
dioxide gas that is toxic. Be careful not to let this chem-
of the lab and breathe fresh air. If swallowed, drink lots
ical come into contact with your eyes, and don’t use it
of water and do not induce ­vomiting. Disposal after
as a fragrance behind the ears as one of my students
diluting with a large volume of water is acceptable.
once did.
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
the fat globules from sticking together and as a buffer-
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Sodium Tungstate CAS# 53125-86-3
in water but only slightly hydroscopic. This acid gives
This chemical, according to MSDS data I have read,
apples their sour flavor. It is only mildly toxic, and gen-
is one that is being tested for human mutations in the
reproductive cycle. It is a primary component in the
Ziatype formula system and will lower contrast in that
process. It is supposedly not highly toxic, but it will cause
general irritation of eyes, tissues, and the ­respiratory
system if safety precautions are not adhered to.
Sulphamic Acid CAS# 5329-14-6
Sulphamic acid appears as a white and odorless
­crystal. It is used as a contrast control in the argyrotype
­process and is employed as an acidifier in ammonium
­thiosulphate fixing baths. This chemical is corrosive to
tissue, eyes, and the respiratory system. It is highly and
violently reactive when hot and in combination with
nitrates and nitrites. If this sounds like a bomb recipe
then you will take great care not to fool around with
this chemical near an open heat source. Take great
care in using this chemical with gloves, safety glasses,
and a respirator.
Tannic Acid CAS# 1401-55-4
eral safety precautions should be used in its handling
and use. Tartaric acid is used in several formulas in
order to prevent highlights from getting muddy. It is not
used for making tartar sauce . . . and I will not relate the
story that goes along with that warning.
Thymol (Phenol, 5-methyl-2-[1-methylethyl])
CAS # 89-83-8
Thymol is used in this book as a preservative for dry
plate film emulsion (see the Alternative Negative chapter). Thymol crystals can also be found online by going
to beekeeping supply vendors. Make sure it is always in
crystal form. Thymol crystals are corrosive and nasty.
Do not purchase thymol in oil of any kind. Thymol
crystals have two distinct uses in British beekeeping,
first as an antifungal or anti-fermentation agent in producing sugar syrup feed and secondly as an aromatic
and corrosive sublimation material for use against the
varroa mite in special evaporator frames.
Thymol is only slightly soluble in water, but it is
readily soluble in surgical spirit (rubbing alcohol in
the United States), which is ethanol to which a small
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
Tannic acid is a yellow/tan powder and may not,
amount of methanol has been added to render it
depending on your sensibilities, have an offensive
unfit to drink. It is normally used to sterilize surfaces,
odor. Personally, I rather like the aroma and think
cleanse skin abrasions, and toughen skin. Thymol is a
it smells like instant iced tea mix. This chemical is a
skin irritant. In the event of a spill or a splash, wash
tanning agent and is often used in the toning of cya-
everything well with warm water for at least 15 ­minutes
notypes. It is a strong oxidizer of metals, and chronic
and consider getting medical attention.
exposure is harmful to the liver. It is found in grapes,
tea, and cat urine. It can be irritating to the mucous
3,3’ Thiodipropanoic Acid CAS# 111-17-1
membranes, and general caution should be taken
This chemical, with sodium carbonate and water, is the
when using it. It is incompatible with albumen, gela-
ligand in the S version of the new chrysotype. It can be
tin, salts of metals, and strong oxidizers. There is a
purchased reasonably from the Alfa Aesar company (see
low health risk with tannic acid, but be cautious of
Resources). It is a skin, eye, and respiratory irritant.
the powder’s dust and seek fresh air if you experience discomfort.
Tartaric Acid CAS# 87-69-4
Tri-Sodium Phosphate CAS# 7601-54-9
Tri-sodium phosphate is a white, odorless solid and is
strongly alkaline. It is commonly found in ­photographic
Tartaric acid is a white, crystalline powder with a strong
developers, water softeners, scouring powders, ­laundry
fruit acid flavor that is approximately 10% stronger
soaps, and dishwashing compounds. In an alterna-
than citric acid and can be manufactured synthetically
tive process application, it works as a yellow toner for
or recovered from natural sources. It is highly soluble
­cyanotypes.
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Tween 20 CAS# 9005-64-5
means that you still have residual silver salts in your
This is an inexpensive surfactant that may be added
paper and that additional fixing time is necessary.
helps in getting the sensitizer into the paper fibers. It
R eader R es p onsibility
can be an eye irritant.
I have placed warnings and considerations through-
Vinegar
out the entire text to alert you to possible chemical
and health concerns. For a complete overview of all
Vinegar strength commonly is measured in “grains.”
chemicals in use, and their individual MSDS and
In the United States, this refers to the percent acid
CAS documentation, please refer to the previous
times 10. For example, 100-grain vinegar contains
­chemical descriptions or to the chemical research
10% acetic acid and 90% water. Distilled vinegar
sites that have been provided. These sites have con-
strength ranges from 50 to 300 grains. Specialty
nections and links to many MSDS databases, and
vinegars range from 40 to 100 grains. The color of
each of these databases has MSDS sheets for individ-
distilled vinegar ranges from a straw color to water
ual distributors of that chemical. If you are a teacher
white. Most vinegar is 5%.
using these chemicals, you must have MSDS documentation in your lab. If you have a question or a
A S im p le T est for R esid ual
H y po/ Fixer
concern about a particular chemical, it is solely your
A simple test to be sure that all of the sodium
bility of the reader to take prudent and appropriate
­thiosulphate/fixer/hypo is removed from your print
caution in preparation, usage, and disposal when
is to make the following solution: 750 ml of water,
using chemistry of any kind. Although I have made
125 ml of 28% acetic acid, 7.5 g of silver nitrate, and
every effort to give you clear and safe instructions,
cold water to make a liter of solution. Place a drop of
I have no way of knowing if your being is adversely
it in the center of a piece of photographic paper that
affected by certain chemicals. If you are unsure of
has experienced the same development, fixing, and
your sensitivity, or of the chemistry you are about to
washing as the prints you want to keep. After several
use in a process, you must stop and take the respon-
minutes, rinse the paper with a saltwater solution and
sibility of researching that chemical.
responsibility to find out about that chemical before
using it. It is completely and entirely the responsi-
examine it for a stain in the drop location. Any color
deeper than a very light tan stain indicates the presence of hypo. This means that you should wash your
S mall Vol u me C onversion ­Table
prints longer. Store the solution in a dropper bottle
These days, the Internet offers you an abundant
and use it when you are concerned about the success
number of electronic conversion sites that make the
of your washing technique.
following tables redundant and irrelevant. For example, check out http://www.unitconversion.org or
A S im p le T est for R esid ual Silver
Using Sodi um S uLPHI DE
http://www.kylesconverter.com. These sites will do
One way of determining whether or not you have fixed
(e.g., ounces to milliliters) and type in the number
your print long enough is to give it a simple sodium
of ounces, and instantly the equivalent amount in
sulphide drop test. Mix up a 10% solution of sodium
­milliliters will appear. There are charts for every
sulphide (10 g of sodium sulphide with 100 ml of dis-
conceivable conversion. In the event that you do not
tilled water) and place a drop of it on a light area of your
have access to the Internet, here are the old school
image. If the drop of sodium sulphide turns brown, this
equivalent figures.
the math instantly for you. All you have to do is to
specify the starting point on the conversion table
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
to sensitizers, specifically iron-based processes, and it
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DRY M EAS UR E
1 quart = 946 ml
1 liter = 1,000 ml
1 pound = 453.6 grams
1 liter = 33.81 fl oz
16 ounces = 453.6 grams
1 cup = 240 ml
1 pound = 16 ounces
4 cups = 950 ml
16 ounces = 7,000 grains
1 pint = 16 fl oz
1 ounce = 28. 35 grams
1 pint = 473.12 ml
1 ounce = 437.5 grains
1 fluid oz = 29.57 ml (USA)
1 gram = 0.77 scruple (apothecary)
1 fluid oz = 28.41 ml (GB)
1 scruple = 1.3 grams
1 fluid oz = 8 fluid dram
1 gram = 0.03527 ounce
1 tbs = 15 ml/15 cc
1 gram = 15.43 grains
3 tsp = 1 tablespoon (tbs)
10 grams = 154 grains
1 tsp = 5 ml/5 cc
1 grain = 0.0648 gram
1 dram = 3.697 ml
10 grains = 0.648 gram
1 ml = 1 cc (cubic centimeters)
7 g sugar = 1 tablespoon
1 cc = 1 ml
10 grams = 154 grains
1 ml of water = 1 gram (dry weight)
10 grains = 0.648 gram
100 ml = 3.38 fl oz
100 grains = 6.48 grams
1 gram = weight of 1 ml/1 cc water
1 nickel = 5 grams
1,000 g = 2.2 pounds
♦♦ To change ounces to grams, multiply (×) ounces
by 28.35.
THE BOOK OF ALTERNATIVE PHOTOGRAPHIC PROCESSES Third EDITION
♦♦ To change grams to ounces, divide (÷) grams
by 28.35.
♦♦ To change pounds to grams, multiply (×) pounds
by 453.6.
♦♦ To change grains to grams, multiply (×) grains
by 0.0648.
♦♦ To change grams to grains, divide (÷) grams
by 0.0648.
♦♦ To change grams to milligrams, multiply (×) grams
by 1,000.
♦♦ To change milligrams to grams, divide (÷)
­milligrams by 1,000.
20 drops = 1 ml/1 cc/20 minums
(use a plastic dropper for consistency)
1 drop = 0.067 ml/1 minum
Ounces & Milliliter Conversions
♦♦ To change ounces to milliliters, multiply (×) ounces
by 29.57.
♦♦ To change milliliters to ounces, divide (÷) m
­ illiliters
by 29.57.
Making a Saturated Solution
A saturated solution is one in which a specific chemical is added to a volume of water until no more
of that chemical will dissolve and in which sediment remains in the liquid solution. An example of
seeking a saturated solution is when you are mixing up potassium or ammonium dichromate to use
as an ingredient in a gum bichromate sensitizer.
Dichromates are used in a saturated solution in
gum printing. Ammonium dichromate is saturated
LIQUID MEAS UR E
at around 25%–30% and potassium dichromate at
10%–13%. If you had 100 g of potassium dichromate
1 gallon = 4 quarts or 128 fluid ounces (fl oz)
and you stirred that chemical into 1,000 ml of water
1 gallon = 3.785 liters or 3,785 milliliters (ml)
you would begin to see evidence of saturation in that
1 quart = 32 fl oz
10% solution.
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TEMP ER ATUR E CONVE R S I ON S
compound when added to 100 parts of a solution. In
To Convert Fahrenheit ( F˚) into
­Centigrade (C˚)
potassium dichromate, you would simply add 10 g of
2.Multiply (×) that number by 5.
3.Divide (÷) this number by 9 to get the C˚
­conversion.
Example: 100°F minus 32 = 68, times 5 = 340,
divided by 9 = 38°C
Equals: 37.77°C
potassium dichromate to water until you had a total
liquid volume of 100 ml. This is called percent weight
per volume (% w/v).
Percentages Can Be Expressed in Three
Different Ways
♦♦ % w/v (percent weight per volume): This is used
when combining a solid with a liquid.
♦♦ % v/v (percent volume per volume): This is used
To Convert Centigrade into Fahrenheit
when combining two liquids. For instance, a 30 %
1.Multiply (×) Centigrade temperature by 9.
30 ml of hydrogen peroxide in 100 ml of water.
2.Divide (÷) that number by 5.
3. Add 32 to that number and get the F˚ conversion.
Example: 38°C times 9 = 342, divided by 5 = 68.4,
plus 32 = 100°F
Equals: 100.4°F
HOW TO FI GUR E P E R CE NTAG ES
solution of hydrogen peroxide would comprise
♦♦ % w/w (percent weight per weight): Seldom used
as a measurement, this refers to g of a given compound per 100 g of a given solution. As 1 ml of
water has a weight of 1 g, it is not uncommon for g
and milliliters to replace one another.
Figuring a Percentage for a Solution
Here’s a quick elementary reference for you to use if
For figuring percentages, I now use an iPhone app
you need to make a liter of 15% solution of sodium
called Soulver that is so so much better for me than
thiosulphate. Multiply 1,000 by 0.15 and you will get
pencil and paper: http://www.acqualia.com/soulver/
150. Mix 150 g of sodium thiosulphate into the liter of
iphone/.
water for the solution.
Percentage (%) is a term applied to expressing the
If you need to make a liter of 3% solution of sodium
concentration of a given solution in which a specific
thiosulphate, multiply 1,000 by 0.03 and you will get
chemical weight has been stirred into a specific volume
30. Mix 30 g of sodium thiosulphate into the liter of
of liquid. It defines the number of parts in a particular
water for the solution.
APPENDIX A Chemical Safety Considerations, Definitions, Information, Small ­V olume Conversions and Formulas
1. Subtract (−) 32 from F˚ temperature.
other words, if you needed to make a 10% solution of
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