>What is the procedure for firing with underglazes. . . . Do I need
>to do 2 firings or 3? That is 1. greenware, 2. underglazed
>bisqueware, 3. transparent glaze. Or do I apply the
>transparent glaze over the raw underglaze and then fire. ???
>
>Jeannie in PA with some excited 4th graders
Most people fire twice. You can put most underglazes on either the
greenware or bisqueware, but either way, add the glaze to the
bisqueware and glaze fire.
You may be able fire only once with underglaze and glaze both brushed
on greenware. This is not recommended in a schools. Greenware is
more apt to have a steam explosion if fired too fast at the early
stage. Nobody wants all the that mess if there are glazes that
stick to everything.
Firing three times is okay, but it is more labor and more energy is used.
Related IDEAS FOR FUTURE REFERENCE
It is very easy and cheap to make colored slips that are used on the
clay before the clay is dry. I make it from dry scrap of the same
clay as the pots (sample recipes below). This allows for many
variations. I encourage students to play around and try out
variations and ideas on old newspapers or other scrap.
1. Cover the whole piece with slip and carve some off at leatherhard stage.
2. Use Wax Resist to make a design - brush the colored slip on to
color the background.
3. Brush on a design, wax it, carve off or scratch lines in the wax,
add another color for outlines or other designs.
4. Students scissor cut stamp shapes from half inch thick sheets of
soft plastic foam (with a spongy consistency). Use the stamps to add
repeat patterns with slip. For a variation, alternate slip and wax
resist, for a Notan design (google it if it is new to you).
For decoration ideas they each list 20 of their favorite things then
make a few unique sponge foam stamp shapes. This helps avoid and
discourage duplicates, copy work, and cliches. Ideas are derived
from their own lives - the best kind of derivative art.
CHEAP SLIPS (these do not stick to bisque - only for use on clay
before it is dry)
A simple brown slip recipe.
Drop pieces of dry scrap clay in clear water. No need to break it
up. Do not stir. Just let dry clay pieces set until all clay is
soft. Add red iron oxide (this is the same chemical as ordinary
finely powdered rust) so it ends up about 3 parts clay and 1 part
iron. You can guess at it, measure it, or weigh it if you want to.
Once all the clay is wet, stir it. Use enough water to make the
consistency of a nice paint. If it gets to thick or dry just add
water. It it is too thin, set it overnight and take the water off
the top before stirring. Older students can make slip if you caution
them not make any dust because clay and oxide dusts are all bad to
breath.
For other colors try -
blue - 1 part cobalt carbonate or oxide added to 9 parts clay (add
some blue tempera paint as a signal color or so students know what
color it fires).
green - try 1 part copper carbonate (same as the green stuff on old
pennies) to 7 parts clay (add green tempera).
yellowish tan - 1 part rutile (a form of impure titanium) with 4 parts clay.
white - 1 part tin, titanium, or zirconium added to 3 parts white clay.
Glaze over these with any glazes that are not too dark or too opaque.
Mix and overlap these anyway you want to. Expect the unexpected.
Have fun experimenting.
--
Marvin Bartel
Marvin Bartel, Ed.D., Professor of Art Emeritus
Goshen College, 1700 South Main, Goshen IN 46526
studio phone: 574-533-0171
http://www.bartelart.comhttp://www.goshen.edu/art/ed/art-ed-links.html
"You can't never know how to do it before you never did it before."
... a kindergarten boy working with clay for the first time.
---
