Uploaded by Michael Neuman

chem write up #2

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“The importance of chemistry was further highlighted by the development of bleaches. In the
early early eighteenth century, textiles were bleached with sulfuric acid, which was scarcely
beneficial to the fabric. The French chemist Claude-Louis Berthollet showed in the 1780s that
chlorine, discovered by Carl Scheele, exhibited bleaching power without the corrosive
consequences of the acid (207-208).
I was interested in writing about bleaching agents in art because it is an interesting
concept. Most art is the intention of color, not the absence of it, or even the removal of it.
Removal is usually the result of a mistake. I began my search by typing “chlorine as a bleaching
agent in art” into google and got over 1 million results. Bleaching agents work by oxidizing or
reducing impurities within the dyes, pigments, or other substances that make up the color of an
object or material. The natural way to bleach something is to leave it in the sun. This is an
ancient tradition that has was commonly used in Egypt, China and the Middle East. Other
bleaching techniques involved natural processes such as using urine and feces because of the
properties of ammonia that they produced. Eventually chemical agents were used to bleach
materials. The chemicals used were lye—which is the leftover drainage from liquid wood
ashes— sulfuric acid, and eventually chlorine.
Sulfuric acid reduced the amount of time that it took to bleach something. It also made
it easier to make white textiles, which because of their timely processes used to cost a
significant amount of money. Because the process became a much quicker process, it made it
much more affordable, and accessible for different social classes to buy. The process, before
sulfuric acid used to take a significant amount of time that could take as long as a few months.
After the introduction of sulfuric acid, the process took only a few days.
The dry mixture of chlorine was created by a man named Charles Tennant. It combined
chlorine and slaked lime, also known as calcium hydroxide. This mixture was the most
commonly used until liquid bleach came into existence. The largest problem with chlorine is the
gas it emits and the effect it has on the people working with it. Mills that produced bleached
items began facing issues with fumes and began to realize that chlorine dissolved in water
instead of using it in a gas form helped reduce the fume levels.
Bleach is most commonly known for its whitening effects on clothing. I am unclear of
how much this affects art, possibly in the way that it can effect fibers? I would assume that this
would be beyond a canvas. Overall, I found this information interesting.
http://cameo.mfa.org/wiki/Bleaching_agent
http://www.niscair.res.in/sciencecommunication/researchjournals/rejour/ijct/Fulltextsearch/2
004/November%202004/IJCT-vol%2011-November%202004-pp%20876-887.htm
http://www.chemistryexplained.com/Ar-Bo/Bleaches.html
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