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Glazing
| Adult Classes |
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WHY DO GLAZES RUN?
Glazes melt when fired to maturity and form a coating of glass on the surface of
the pot. The glazes melt slowly, and as they melt they bubble like thick syrup.
As they get hotter and hotter, the glazes become more fluid, similar to the
consistency of honey. Eventually, if over fired or too thick, the glaze will become
so fluid it will run off the pot onto the shelves. Eventually, the pot itself will begin
to melt, boil, deform and liquefy.
When fired to maturity, some glazes are inherently more fluid (runny) than
others. Example: Copper Red
When application of the glaze is thick, glazes are more likely to run. When
glazes are applied unevenly, resulting in thick and thin spots, the thick spots
will be more likely to run.
Some glaze combinations become extremely fluid where they overlap. This is
known as a eutectic. Example: Chun and Titanium Blue
When over-fired, all glazes will become fluid and run. In fact, even the clay can
liquify.
The Problem:
When glaze runs off your pots, it ruins your pots. When glaze runs off your pots,
it sticks to and damages our kiln shelves.
The Solution:
Avoid runny glazes until you are proficient at glazing. Avoid glaze combinations
that form a eutectic. Ask if you are not sure! Apply glazes with a uniform and
appropriate thickness. Use runny glazes on the rims and insides of pots. That
way, if they run, at least they won't stick your pot to the cookie or kiln shelf. Label
all glazes pots so we know what glazes are on them and can put them in the
most favorable spot in the kiln for that glaze.
Fireborn Studios is one of the best sources of Pittsburgh pottery, hand made
American crafts and Pittsburgh pottery classes for children and adults. Visit our
Studio and Art Gallery.
Glazes melt when fired to maturity and form a coating of glass on the surface of
the pot. The glazes melt slowly, and as they melt they bubble like thick syrup.
As they get hotter and hotter, the glazes become more fluid, similar to the
consistency of honey. Eventually, if over fired or too thick, the glaze will become
so fluid it will run off the pot onto the shelves. Eventually, the pot itself will begin
to melt, boil, deform and liquefy.
When fired to maturity, some glazes are inherently more fluid (runny) than
others. Example: Copper Red
When application of the glaze is thick, glazes are more likely to run. When
glazes are applied unevenly, resulting in thick and thin spots, the thick spots
will be more likely to run.
Some glaze combinations become extremely fluid where they overlap. This is
known as a eutectic. Example: Chun and Titanium Blue
When over-fired, all glazes will become fluid and run. In fact, even the clay can
liquify.
The Problem:
When glaze runs off your pots, it ruins your pots. When glaze runs off your pots,
it sticks to and damages our kiln shelves.
The Solution:
Avoid runny glazes until you are proficient at glazing. Avoid glaze combinations
that form a eutectic. Ask if you are not sure! Apply glazes with a uniform and
appropriate thickness. Use runny glazes on the rims and insides of pots. That
way, if they run, at least they won't stick your pot to the cookie or kiln shelf. Label
all glazes pots so we know what glazes are on them and can put them in the
most favorable spot in the kiln for that glaze.
Fireborn Studios is one of the best sources of Pittsburgh pottery, hand made
American crafts and Pittsburgh pottery classes for children and adults. Visit our
Studio and Art Gallery.
Wax the entire bottom of each piece and 1/8 to 1/4 inch above the bottom on the
outside of the piece. Waxing makes it easier to clean off glaze that must be
removed from the waxed areas. Dust porcelain pots with a damp tea towel.
All glazes must be thoroughly stirred before using. Inadequate stirring will
result in areas where the color of glaze does not develop because it is too thin.
When dipping glazes, submerge piece quickly, do count in seconds, and
remove pieces quickly from the glaze. The "count" for each glaze is as follows
- Copper Red 3 to 4 (submerge piece upside down)
Chun 3 but it is fluid
Clear 2
Twilight Blue • 2
Blue Celadon 2
Green Celadon • 2
Tenmoku 1-2 (thin for brown, thick for black)
Shino • in & out for orange, 2 for white, Caustic to skin!
Plum • in & out
Jack's Black in & out
Titanium Blue in & out Danger! Consult with Dan!
Bark fluid, fast dip Danger
Oil Spot 2 all over and paint more and inside bowls
White Crackle 2
Pale Pale Blue 2
Root beer 2
Sky Blue 2
Tomato Red * in and out
Apple Green Celadon 2
Marsh 2
Verdigris in and out
- • = easy for beginner's to get good results
pot is removed, unsightly, sharp scars are left on the pot. This wrecks your pot
and damages our kiln. Bad news!!
Clean up after yourself. Using a sponge, wipe glaze drips off table, floor and
ware boards. Rinse sponge frequently to avoid streaky glaze residue. Rinse out
any plastic pitchers or brushes used.
We need to move pots through the studio so please glaze each week. I
supervise glazing form 8:30 to 9:30 and leave the throwers upstairs to work
independently.
supervise glazing form 8:30 to 9:30 and leave the throwers upstairs to work
independently.