What is Stull Atlas?
Stull Atlas is an interactive glaze chemistry explorer. It lets potters and ceramic researchers map glaze formulas onto the Stull diagram — a classic visualisation of how silica and alumina ratios determine surface character.
The goal is to make glaze chemistry legible: to see why a glaze is matte or glossy, stable or running, and how your glazes relate to the thousands of others in the public record.
The Stull Diagram
In 1912, R.T. Stull published research showing that the surface quality of a fired glaze — matte, satin, glossy — could be predicted from the ratio of silica (SiO₂) to alumina (Al₂O₃) in its Unity Molecular Formula (UMF).
The diagram plots Al₂O₃ on one axis and SiO₂ on another, with zones marking where glazes fall: too little silica and they crawl, too much and they craze, the centre band produces stable glossy surfaces. Matte glazes cluster in a higher-alumina region.
Despite being over a century old, the Stull diagram remains one of the clearest diagnostic tools in studio ceramics — and one of the least approachable for people without a chemistry background. Stull Atlas is built to change that.
Data Sources
Stull Atlas draws on community-contributed glaze recipes, extracting UMF values and Stull coordinates to produce plottable recipes indexed by cone, atmosphere, and surface type.
Built by
Stull Atlas is a solo project by rje — a potter and software developer interested in the overlap between craft knowledge and data tooling.
If you're a ceramic researcher, educator, or institution interested in deeper access or collaboration, reach out.