Understanding Cone 6 Glaze Chemistry

Ceramic Story-time with Sue

This video first appeared live in my Facebook Group - Understanding Glazes with Sue.

In the video, I read my 2018 NCECA presentation "Understanding Cone 6" and take questions and comments live.

In 2018, I was invited to participate on a discussion panel about glaze chemistry at the NCECA conference in Pittsburgh. I presented the research I did on the chemistry of cone 6 glazes and how it relates to the Stull chart shown in the above diagram.

The Stull chart takes the Unity Molecular Formula (UMF) of a glaze recipe and plots the Silica and Alumina levels. Each point on the chart represents a different glaze recipe where the only difference between them is their silica and alumina levels.

Based on these values and where the points fall on the chart, you can predict with relative accuracy whether a glaze will be matte, glossy or somewhere in between.

The Stull chart was originally created in 1912 by a scientist named R.T. Stull who was working at Cone 11. I recreated the chart for cone 6 by adding boron to the formulas, making 50 glaze tests to represent each point on the map, firing them and documenting the results. I did this twice, to compare 2 different flux ratios.

In this presentation, I explain my results, the patterns I found and how they relate to Stull's original research.

If you're new to glaze chemistry, I encourage you to follow along and absorb what you can. I hope that one day, it will make sense to you.

Once you understand how glaze chemistry works, you can design any type of glaze for any temperature, using chemistry and the UMF. The possibilities are endless!

To read the article and download it as a pdf, go to https://suemcleodceramics.com/underst...

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