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Calculate glaze batch weight from unity formula and raw material analysis. Scale recipes to any batch size for consistent studio pottery glazing.
Create kiln firing schedules with ramp rates, hold times, and cone temperatures. Plan bisque and glaze firings for electric and gas pottery kilns.
Calculate clay shrinkage percentage from wet, dry, and fired dimensions. Plan pottery sizes accurately for clay bodies from leather-hard through glaze firing.
Each oil has a SAP value — grams of NaOH needed to saponify 100 g of that oil (or oz NaOH per oz oil in imperial). Multiply each oil weight by its SAP and sum.
NaOH (g) = Σ (oil weight g × SAP value / 100)Superfat leaves unsaponified oil for mildness and moisture. Reduce calculated lye by the superfat percentage — typically 5–8% for body bars, 15–20% for salt bars.
Adjusted NaOH = calculated NaOH × (1 − superfat% / 100)Lye solution strength is set by water-to-lye ratio. A 33% lye solution (2:1 water:lye by weight) is standard for trace-friendly cold process.
Water (g) = NaOH (g) × (1 − lye% / 100) / (lye% / 100)Updated: July 2026
500 g olive (SAP 0.135), 200 g coconut (SAP 0.183), 100 g palm (SAP 0.142): NaOH = 67.5 + 36.6 + 14.2 = 118.3 g; at 5% superfat = 112.4 g NaOH.
1000 g coconut oil × 0.183 = 183 g NaOH, no superfat discount. High cleansing bar — use gloves and cure 4+ weeks.
112 g NaOH needs 224 g distilled water for 33% solution. Always add lye to water, never water to lye, in heat-resistant container.
All soapmaking calculations require weight in grams or ounces. Volume varies with temperature and oil density — weight is the only reliable basis.
Superfat reduces lye once. Do not also reduce oils — the superfat percentage already accounts for leftover unsaponified oil in the formula.
Cold-process soapmaking requires precise lye calculated from each oil's saponification (SAP) value. This calculator totals NaOH needed for your oil blend with adjustable superfat to produce safe, fully saponified soap.