Equipment and materials:
To mix your own glazes you need:
1) a sieve
2) a mixer
3) a scale
4) glaze chemicals
5) glaze recipes
6) a mask
7) 2 buckets
Get a glaze recipe:
Typically one starts by finding a glaze recipe, from a book or a reputable
web site. Start with a glaze recipe which is formulated for your
particular firing type and clay body (ie Stoneware clay, fired in cone 6
oxidation.). Recipes are usually expressed in numbers that always
total 100. For example:
Ingredient A: 10
Ingredient B: 25
Ingredient C: 15
Ingredient D: 50
Total
100
Determine the amount of glaze you want to make:
Determine the amount a glaze you want to make
and then add the appropriate
ratios. For example, if you want to make 1000 grams of glaze, you would add:
10 / 100 * 1000g of Ingredient A
25 / 100 * 1000g of Ingredient B
15 / 100 * 1000g of
Ingredient C
50 / 100 * 1000g of Ingredient D
It is wise to mix a test
batch of 100-500g first, to make sure the glaze works as you want it
to. Glaze chemicals are measured using a scale, typically a triple
beam scale such as the Ohaus scales sold here.
Mix and Sieve the Glaze:
After the glazes have been mixed (using a good mask, as many of the
ingredients are toxic and should not be inhaled), water is added until an
appropriate thickness has been reached. Potters often refer to this
thickness as the thickness of low fat milk. I is a good idea to let
the glaze sit for 24 hours before using, to make sure all the particle
are fully wet. (Note, some believe it is better to add the dry
ingredients to the water, instead of the other way
around...)
At this point, the glaze must
be sieved 3 times to ensure all the clumps are out and the glaze is perfectly
smooth. To sieve a glaze, a sieve is put over a bucket. The glaze is
then poured into the sieve and pushed through with an object such as a rubber rib.
(for more information on mixing, see Mixing Dry
Glazes.)
Glazing
Pots are then dipped into the glaze, or the glaze is sprayed on.
First,
put the glaze into the inside of a pot, swirl it around and let it run
out. If the piece is extra thin, let it dry before glazing the
outside.
Then glaze the outside of the pot, by dipping 1-2 times, or by
pouring glaze over the piece. You can dip a piece in upside down without
disturbing the inner glaze, as the air will keep the new glaze out.
Finally, the piece is fired.
Final Comments
A good glaze is one that looks like you want it to, and
in the case of functional ware is non-toxic and fit for it's purpose. If it has too much
flux, it may run excessively all over the kiln shelves. If it does not fit
your clay, it is likely to chip, craze (tiny cracks across the surface of the
glaze), or shivver (clay shrinks more than the glaze).
If there is a good
fit between the glaze and the clay body, the piece will be very strong.
You can test the fit by alternating a pot between boiling and freezing
water. If it is going to fail, it will then.
Otherwise you may find
out months later that the piece is not holding up. If glaze defects occur,
you will need to troubleshoot the glaze to determine why, and what it needs to
correct it. There are software programs available to help you do
that.
For more information on glazes, see the following
links:
Links to websites with glaze recipes
http://www.bigceramicstore.com/Information/glaze_recipes.htm
Mixing
Dry Glazes
http://www.bigceramicstore.com/Information/MixingGlazes.htm
Glaze
Problems
http://www.bigceramicstore.com/Information/glaze_problems.htm
Cones
http://www.bigceramicstore.com/Information/ConeChart.html
Tip:
How to Re-Glaze a Piece
http://www.bigceramicstore.com/Information/tip6.htm
How
to Solve Glaze Settling
http://www.bigceramicstore.com/Information/tip3.htm
Decorating
with Oxides
http://www.bigceramicstore.com/Information/tip12.htm
Choosing
the Right Clay Body (and all about clay bodies)
http://www.bigceramicstore.com/Information/tip17.htm
Glaze
Tests and Test Tiles
http://www.bigceramicstore.com/Information/tip25.htm
Why
Glazes Don't Travel Well
http://www.bigceramicstore.com/Information/tip34.htm
Understanding
Glazes
http://www.bigceramicstore.com/Information/tip35.htm
Cracking,
Shivering, Crazing and Dunting
http://www.bigceramicstore.com/Information/tip40.htm
Firing
the Kiln, Parts I and II
http://www.bigceramicstore.com/Information/Tip48.htm
http://www.bigceramicstore.com/Information/Tip49.htm
