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 10,000+ 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.