|Monthly Tech-Tip |
These two pieces are fired at cone 6. The base transparent glaze is the same - G2926B Plainsman transparent. The amount of encapsulated red stain is the same (11% Mason 6021 Dark Red). But two things are different. Number 1: 2% Zircopax (zircon) has been added to the upper glaze. The stain manufacturers recommend this, saying that it makes for a brighter color. However, that is not what we see here. What we do see is the particles of unmelting zircon are acting as seeds and collection points for the bubbles (the larger ones produced are escaping). Number 2: The firing schedule. The top one has been fired to approach cone 6 and 100F/hr, held for five minutes at 2200F (cone 6 as verified in our kiln by cones), dropped quickly to 2100F and held for 30 minutes.
G2926B - Cone 6 Whiteware/Porcelain transparent glaze
A base transparent glaze recipe created by Tony Hansen for Plainsman Clays, it fires high gloss and ultra clear with low melt mobility.
Suspended micro-bubbles in ceramic glazes affect their transparency and depth. Sometimes they add to to aesthetics. Often not. What causes them and what to do to remove them.
Designing a good kiln firing schedule for your ware is a very important, and often overlooked factor for obtained successful firings.
This is a type of stain manufacture that enables the use of metal oxides (like cadmium) under temperature conditions in which they would normally fail.
Cone 6 Drop-and-Soak Firing Schedule
350F/hr to 2100F, 108/hr to 2200, hold 10 minutes, freefall to 2100, hold 30 minutes, free fall
Mason 6021 Red Stain
An encapsulated red stain, it has proven better than any other red we have ever tried for glazes. And it works in bodies.