Why did my soap seize or turn lumpy (riced)?
Short answer
Usually a fragrance oil that isn't safe for cold process. Mixing fragrance and essential oils can do it too.
Explanation
The book notes that US-made fragrance oils are usually tested for cold and hot process soap, while many others, often designed for candles, can cause seizing (instant thickening) or ricing (curd-like lumps and separation). Always check a fragrance's cold-process safety before using it.
What to do
- Check the supplier's specification sheet for 'CP soap safe'.
- Test each new fragrance oil in a small batch first.
- Use either fragrance oils or essential oils in a recipe, not both.
Source: The Big Book of Homemade Soap — Fragrances and Colorants for Cold & Hot Process Soap