Frit

Glaze chemistry for potters

Frit is a Mac app for working out what a glaze recipe is made of. Type the materials and their weights. Frit shows the unity molecular formula as you edit, places the glaze on a Stull chart, and compares each oxide with published reference ranges for cone 6 and cone 10.

What it does

• Live chemistry. UMF, mole percent, weight percent, the SiO₂ : Al₂O₃ ratio, the R₂O : RO balance and an expansion estimate after Appen.
• Stull chart. The glaze point on regions after Stull (1912), with a trail of your last edits.
• Reference ranges. Hesselberth & Roy and Cushing limits, each with its source. They are ranges for comparison, not a safety rating.
• Blends. Line blends, triaxial blends of 3 to 66 tiles and four-corner grids, each tile with its own recipe.
• Batch sheets. Scale a recipe to any batch size and print it or save a PDF.
• Test log. Record cone, atmosphere, firing schedule, notes and a photo for each test tile.
• Materials. 47 materials with analyses worked out from their chemical formulas. Add your own from a supplier data sheet.

Each glaze book is a file on your Mac. Frit has no account and no network access.

Frit needs macOS 14 or later. Always fire a test tile before you rely on a recipe.