GLAZING INSTRUCTIONS
(Or, The Glaze-pel According to Laurie Childers)
FIRST THINGS FIRST:
Clean your hands. Grease, clay, dirt, lotion etc. are not your
friends in this process.
RINSE YOUR PIECES (briefly) UNDER WARM RUNNING WATER.
This is to remove all the dust from the surfaces, such as small clay
particles that have floated down onto it while it was drying and since it
was bisqued. Such particles can cause glaze to crawl away in the firing,
leaving weird bare spots on your piece.
LET YOUR PIECE DRY. Rinsing in warm or hot water will
evaporate faster than cold water. Putting your piece in the sun or near a
hot kiln will speed drying. 30 minutes to 2 hours is a normal time to wait
before glazing. It should not feel cool to the cheek anymore.
While your pieces are drying, THINK ABOUT WHAT GLAZE(S) YOU
WILL USE, AND HOW YOU’LL APPLY THEM. Some hints:
Glazing the inside of a vessel with a lighter color than the outside makes it
look more lightweight and voluminous than it really is. Putting a darker
color inside than outside makes it look darker, smaller, heavier, and
sometimes mysterious.
Translucent glazes show texture by the thicker areas of glaze (the deep
parts of the texture) being darker than the thin parts (the raised
portions). chun base, blue blue, celadon
Matt and satin matt glazes show texture and other variation by becoming
lighter in color where the glaze is thicker. shino, mag white, yellow salt
Temmoku is brown when thin, and black when thick, if it behaves itself.
Some glazes tend to cover up texture: oil spot, mag brown, dragon
green, chun red, teal, loden. Loden is our scrap glaze, usually a forest
green.
Chun red, that luscious and attractive glaze, is not predictable for
beginners, so get ready for some trial and error. It will sometimes show
texture beautifully by being red in the deep, thick parts and clear where it
is thinner. Or it might lose all the copper red and be a muddy translucent
glaze, or it might stay all red and cover all texture. Best hope for an allred surface: insides of vessels, glaze applied thickly, and put a note on it
that says RED GLAZE so it gets placed in the center of the kiln.
Texture can be made to show itself strongly by using a glaze that
contrasts with the clay body, and wiping the glaze off the raised areas and
leaving it in the interstices. Use a very damp sponge, and rinse it as
needed, more often in the final stages of wiping. Use the scrap bucket!
You can instead use iron oxide, cobalt oxide, or combinations to brush on
and wipe off, to bring out the texture. You may then leave it unglazed or
apply a thin coat of chun base. Unlike glazes, which must not come into
contact with the kiln shelf, oxides can be applied all the way to, and even
under, the bottom of a piece without causing damage in the firing. It is
often an excellent alternative to glaze for sculptural work.
No glaze at all is an option to consider for non-food related pieces. Keep
in mind that the necessary unglazed bottom edge is going to call attention
to itself once the rest of the piece is glazed. Maybe your sculpture is
better off “nude” – love your (clay) body! (In which case you don’t need to
wax it, just put the bisqued piece on the shelves in the kiln shed.
Once you know what you’re going to do, and your piece is dry again,
WAX YOUR PIECE BEFORE GLAZING IT
The bottom of your piece, known as the foot, or any parts that touch the
kiln shelf during firing, MUST BE FREE OF GLAZE. The bottom ¼” on the
outside of the piece also needs to be glaze-free. If you are going to use a
thick or a runny glaze, leave ½” or more bare clay. How to do this? In
most cases it is best to apply WAX to the bottom and the bottom edge of
the outside, to repel the glaze application. A liquid wax made just for this
purpose can be applied with a small makeup sponge or a brush that’s
dedicated to waxing. CAREFUL: Drips of wax will not wipe off. Only put
wax where you don’t want the glaze. Rinse the sponge or brush off
immediately in hot water when you are done so it can be used again.
APPLYING GLAZE: There are 5 basic methods to apply glaze. Each is
discussed below, but watching experienced people is invaluable, and you
yourself will get better at it with experience. Pay attention to the rhythm
and speed at which they are done, especially dipping.
Wear GLOVES and an APRON.
Glazing is messy, and you don’t want glaze leftovers on your
clothes or fingers when it’s time to eat. The glazes usually have
heavy metals in them that are TOXIC.
No matter what method you use, you will want to use a damp sponge
to wipe wet glaze bits off the waxed areas. Rinse sponge in the
scrap glaze bucket before using the faucet. There must be no glaze
left on the bottom and the ¼” edge adjacent, even if you have applied
wax. The wax will burn off early on in the firing, and the glaze bits will –
you guessed it – melt and join your pot to the shelf. When the tug of war
comes, your pot will lose and probably damage the shelf, too. That shelf
costs more money than your tuition for the class.
STIR THE GLAZE WELL – ALL THE WAY TO THE BOTTOM.
DO IT AGAIN JUST BEFORE YOU USE IT.
One coat is usually sufficient for dipping or pouring. The glaze should
be the viscosity of whole milk. If it appears too thick, ask the
instructor or lab assistant to check it and perhaps add water. Please don’t
add it yourself.
dipping: traditional method for most pottery glazing; simplest and
quickest; either use tongs to fully dip, or hold the foot with your hand to
partially dip; with skill and experience, it gives a predictable, even coat of
glaze; some glazes can be overlapped with each other to get a third result
(test fire this first!); be quick: don’t let the piece stay in the glaze bucket
too long, or too much glaze will adhere. Drippy glaze makes an icky foot.
pouring: for pieces too large to dip, there are several ways to pour glaze
across the surface; can be a good method when there isn’t enough glaze
left to dip your piece; for insides of cylinders such as mugs (pour inside
about 2/3 full, slosh around and pour out while turning cup – very quickly)
The longer the excess glaze is in contact with your piece, the thicker the
glaze will be (and the heavier your pot will be once it’s fired).
brushing: using a brush to apply glaze is best when there is no other
way. The brush strokes usually show in a broad area because applying
the glaze evenly is difficult, and the glazes change color with thickness.
Brushing is best for small areas, and for lots of different glazes side by
side, especially if you are seeking a painterly look. This is a slow method
but sometimes the only reasonable way. Multiple coats must usually be
applied to get a solid color. Clean brushes thoroughly before and after!!!
spraying: for that airbrushed look; for large pieces too big to dip or pour
gracefully; for applying a very thin coat of glaze; for minimizing the
transition between glazed walls and unglazed bottom. High tech and
involves extra cleaning and preparation: the glaze must be passed
through a small screen first, or it will clog the sprayer. Ask for help first.
sponging: a decorative option; can approximate spraying without the
hassle and noise; can use shaped sponges to make a stamped pattern,
especially using dark glazes or oxides sponged lightly onto white glaze.
TAKE NOTES, KEEP RECORDS SO YOU CAN REPEAT RESULTS YOU LIKE!
For the LBCC Benton Center Ceramics Studio, updated 3-2013
Laurie’s Little Treatise on Ceramic Design Principles
There is a basic gesture that evokes an
instantaneous, subconscious feeling. Great art
creates a strong physical and emotional response.
Form follows function.
Every element conveys meaning/purpose.
The elements talk to each other, even dance with each
other; they interact visually.
Surface is a combination of color, contrast, and
texture. If there is texture on the clay surface,
texture leads the application of color and contrast
in the finish.
A simple form allows for a complex surface.
not demand one.)
(It does
A complex form wants a simple surface.
Likewise a complex surface wants a simple form.
A complex surface will obscure a complex form, and
vice versa. A simple surface will emphasize form.
Lift = Life.
If the piece has a narrow base, it
appears to lift itself off the
table/floor/wall/ceiling, conveying a sense of
expending energy, moving upwards or outwards. It
seems almost alive.
We respond differently to a form or surface or image
depending upon the scale of the piece.
(Miniatures invite
the viewer to enter the image, comfortably leaving behind the rest of the
world. Large-scale works are perceived as more powerful: possibly
aggressive or invasive, possibly protective.)
All design rules (including the above) are made to be
broken at some time or another.
Laurie Childers
Feb 2010/March 2013