Lye Amounts by Oil

Before any superfat discount, 100 g of olive oil is saponified by 13.5 g of NaOH and 100 g of coconut oil by 17.8 g — every recipe total is built from numbers like these.

A saponification value states how many grams of NaOH fully convert 100 g of a given oil into soap. Multiply the value by the oil's weight in the recipe, sum across all oils, and the result is the full-saponification NaOH amount for the batch.

Worked example, olive oil: 500 g of olive oil needs 67.5 g of NaOH at full saponification (13.5 g × 5). Cold-process practice then applies a superfat — a lye discount of 5–8% — which brings that down to about 64.1 g at 5% or 62.1 g at 8%, leaving a measured surplus of free oil in the finished bar.

Worked example, coconut oil: the same 500 g needs 89 g of NaOH at full saponification (17.8 g × 5), or about 84.6 g after a 5% discount and 81.9 g after 8%. Coconut's higher value is also why coconut-heavy recipes harden faster on the cure rack than olive-heavy ones.

The discounted NaOH is dissolved to a 28–33% concentration. For 64 g of NaOH that means roughly 194 g of total solution at 33% — about 130 g of water — or roughly 229 g of solution at 28%, about 165 g of water. Stronger solutions trace faster; weaker ones give more working time.

Mixing generates its own heat: NaOH added to water spikes the solution to 80–100 °C with no stove involved. Both the lye solution and the oils are then brought to 40–45 °C before combining, which keeps light trace at a predictable 1–5 minutes of stick blending. What happens after the pour — unmolding at 24–48 hours and curing 4–6 weeks — is mapped on the cure-times page and the homepage schedule.

• Find each oil's saponification value: olive 13.5 g, coconut 17.8 g per 100 g
• Multiply each value by the oil's weight and sum the results
• Subtract the 5–8% superfat discount from the total NaOH
• Dissolve to a 28–33% solution and cool to 40–45 °C before combining

Further reading

• Cold Process Soap Cure Times
• pH and Shelf Life of Finished Bars