Ground= is a modern UMF (Unity Molecular Formula) workbench for ceramic glaze chemistry. Enter a glaze recipe, get instant oxide analysis, Stull zone classification, and limit checking — no account required.
UMF normalizes glaze chemistry so all the flux oxides (CaO, MgO, K₂O, Na₂O, Li₂O, SrO, BaO, ZnO) sum to 1.0. This lets you compare glazes regardless of batch size or recipe format.
Formula: for each ingredient, multiply the batch weight by each oxide's weight percentage, sum across all ingredients, convert to moles (divide by oxide molecular weight), then divide all moles by the total flux moles.
The Stull chart classifies glazes by Si:Al ratio. Bright gloss ≈ 9–13×. Satin ≈ 7–9×. Matte ≈ 5–7×. Below 5× or very high Al: underfired/unfused risk. See stullatlas.app for the full interactive chart.
527 ceramic materials with oxide analyses, sourced from published Digitalfire and manufacturer data. For more materials and similar recipes, see engine.stullatlas.app/materials (973 entries, 456 cross-referenced into local DB).
Stull limits shown are approximate consensus ranges from the ceramics literature (Digitalfire, Hesselberth & Roy). They are guidelines, not guarantees. Always test-fire your glazes. Food-safe limits flag oxides with known leaching risks.
Stull Atlas — 3D glaze visualization & research · Ceramic Engine — API & ML models · Ground= — UMF calculator (you are here)