Most potters obsess over the climb to peak temperature and then let the kiln cool however it wants. But the cooling curve is where a huge amount of glaze magic actually happens. Controlled slow cooling can turn a dull, washed-out glaze into something rich and complex, without changing your recipe at all.
Glazes are molten glass at peak temperature. As they cool, crystals can grow within them, and those crystals are what create matte surfaces, satin sheens, and the visual depth in many mid-fire glazes. Cool too fast and you freeze the glaze before crystals form, giving flat, glassy, sometimes muddy color. Cool slowly through the right range and you give those effects time to develop.
The action happens roughly between 1900°F and 1500°F on the way down. Holding or slowing the descent through this band is what encourages crystal growth. A typical controlled cool might drop slowly through this zone before letting the kiln free-fall the rest of the way.
| Benefit | Trade-off |
|---|---|
| Better surfaces & color | Longer firing = a bit more energy |
| More control | Requires a programmable controller |
You can't dial in a controlled cool on a manual kiln-sitter; this is one of the clearest reasons to move to a programmable controller. Once you can program the descent, you unlock a whole category of glaze results that were simply unavailable before.
If your kiln can't do a controlled cool, an upgrade opens up matte and crystalline glazes you can't get any other way. Call or text me, Spencer, at (801) 839-5882.
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