My ceramic glazes keep developing hues that defy my recipes

I fire pottery as a hobby, and recently, my glazes have been coming out with colors not in my formulations, even with controlled kiln settings. It's reminiscent of a glitch in the matrix, so I started taking detailed photos of each piece pre and post-firing. This has allowed me to track minor environmental variables I previously overlooked, and I've noticed patterns on cloudy days.

4 comments

4 Comments

the_zara1mo ago

Your note about patterns on cloudy days is REALLY compelling. What EXACTLY are the hue shifts, and are you logging barometric pressure or humidity in your workspace? I'm obsessed with the idea that ambient light could subtly alter glaze chemistry BEFORE it even goes into the kiln. Have you compared results from clear mornings versus overcast afternoons using the same clay batch?

elliot_bailey1mo ago

Honestly, after years of potting, I've never correlated light with glaze shifts pre-firing.

laurag281mo ago

Yeah I noticed that with natural light versus my studio bulbs.

norathomas1mo ago

My friend Lena in Portland kept a detailed journal last fall after she noticed her cobalt blues leaning lavender on consistently overcast days. She tracked it down to a specific hue shift where the blue would lose about 20% saturation under low, diffuse light compared to direct morning sun. She was fanatical about it, logging humidity and barometric pressure twice daily, even though her studio mates teased her. Her side-by-side tests with the same clay batch showed a measurable difference in glaze absorption and final color between clear mornings and cloudy afternoons. Of course, now she blames every misfire on the weather, which is both hilarious and slightly unhinged.