THE ART OF MULTIPLE FIRINGS.
One technique you may not have used is multiple firings. Some people
fire a single piece 3, 4 or even more times until they get exactly what they
like. The only rule in multiple firings is that you can’t re-fire at a
hotter temperature than a previous firing, or you will burn off the lower
temperature glaze..
Here is an example of a multiple firing pattern using a Cone 6 or higher
clay:.
- First glaze firing at Cone 6 (Base glaze).
- Second firing at Cone 6 (Maybe you didn’t like the way your original
turned out, so you touched it up, or by experimentation you have found that
glaze overlaps are nicer when the first is fired and the second added and
refired.)
- Third firing at Cone 04 (To add accent colors using low fire glazes. Since
low fire glazes come in so many bright colors, and “what you see is what
you get”, this is a great way to add a variety of colors to your piece.)
- Fourth firing at Cone 018 (to add metallic or lustre overglazes in very
specific areas.)
I have heard of people firing the same piece up to 10 different times.
Sometimes they just aren’t happy with a piece, so they add more and
refire. Other times it is a deliberate plan. That many re-fires can start to
weaken the clay, depending on the temperatures and the clay bodies used.
It gets a little more complicated with reduction firings, including Raku.
Since these firings need a lack of oxygen in order for the glazes to
develop, you can’t refire them in an oxidation firing (electric kiln) or
all the reduction you did will be reversed. For example, in Raku, carbon
causes the clay to go black where it isn’t glazed. If re-fired in an
electric kiln, the black will burn out and you will get the clay color where
it is bare. Reduction and Raku glazes may or may not look good re-fired in
oxidation, but they will probably look different.
I took a workshop with Kevin Myers where we did Raku, followed by china
painting on certain areas. We focused mainly on painting within the lines of
crackle that had been created by the first firing. Kevin had several pieces
with pops of bright orange color added in this way. We then re-fired in the
Raku kilns just long enough to fix the china paints and allow the glaze to
re-melt so it could be re-oxidized. We couldn’t over fire this second
firing, or the china paints would burn off. And after the re-fire, the
pieces had different patterns because they had oxidized differently
(depending on how oxygen starved the piece was, where the pieces of
newspaper landed, etc.) One thing we were able to do on the second firing
was hold newspaper directly up to the crackle glazes and get more crackle.
So next time you have a piece that you like but is a little bland, try
brightening it up with some accents, and re-fire!
Note: Overglazes are available in both water based and oil based forms.
See them at:
http://www.bigceramicstore.com/Supplies/OverGlazes/overglaze.htm
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