Candle the Kiln

One of the best tips I learned early on was bisque firing and to "candle" the kiln before turning up the heat.

When I first starting bisque firing pieces in my electric kiln, every opening was an adventure to discover how many piece actually survived. I would spend hours throwing and trimming, and then wait weeks for the pieces to dry thoroughly (or at least so I thought). I would load and fire the kiln according to the instructions: 2 hours on low, 2 hours on medium, and then high until the kiln shuts off. Following this method I would see crack, splits, or breaks in 25%-30% of my work. It was very disappointing.

Then I took a college pottery class and learned from the professor, that he candled his kiln over night to ensure the pieces were thoroughly dry.

Candling is basically turning the kiln on the lowest setting possible, leaving the lid slightly open, and firing this way for 8+ hours (I usually do it over night). By firing at this temperature (which is below the boiling point), it helps ensure all the water is driven out of the clay before the "heat" is applied.

Since I have started using the candling technique I have lost very, very few pieces to breaks, splits, and cracks. This might be partly due to other factors as well, but I believe the candling is a key factor.

So Candle that Kiln!

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Gary R. Ferguson - Raku Artist