Liquid Castile (KOH)
Potassium hydroxide soap paste for diluted hand soap, body wash, dish soap, or shampoo base.
Liquid soap uses potassium hydroxide instead of sodium hydroxide. The result is a thick paste that you dilute with water (typically 1:1 to 1:3) to make finished liquid soap. Longer process than CP but the yield is enormous and the soap is endlessly customisable.
Ingredients (1 kg batch)
| Ingredient | Amount |
|---|---|
Coconut oil 76° Cocos Nucifera (Coconut) Oil | 400.0 g (40%) |
Olive oil Olea Europaea (Olive) Fruit Oil | 300.0 g (30%) |
Sunflower oil Helianthus Annuus (Sunflower) Seed Oil | 250.0 g (25%) |
Castor oil Ricinus Communis (Castor) Seed Oil | 50.0 g (5%) |
KOH (lye) | 236.5 g (90% purity) |
Distilled water | 330.0 g |
Open the recipe in the calculator to scale up or down by gram, ounce, kg, or pound.
Expected qualities
Step-by-step
- Weigh oils into a slow cooker or double boiler. Heat to 71°C (160°F).
- Mix KOH (90% pure) into water in a separate vessel. Combine slowly, stirring.
- Pour lye-water into the oils. Stick-blend to thick trace, then keep cooking on low.
- After about 3 hours of cook, the paste should be translucent amber. Check zap (taste a tiny dab — if it stings, it needs more cook).
- When the paste is zap-free, you have soap paste. Store as-is or dilute.
- To dilute: mix 1 part paste with 1 part hot water, let sit overnight; adjust thickness with more water or cook longer.
Notes & troubleshooting
- KOH is sold at 85–95% purity. Set the calculator's lye purity field to match your KOH (90% is most common).
- Use a dedicated KOH stick blender if you can — KOH is harsher on tools than NaOH.
- Liquid soap doesn't need a cure. It's ready when the zap test passes.
Calculator-flagged recipe notes
- Coconut oil over 30% can be drying. Consider raising superfat to 20% if you go higher (salt bars often use 20%).
Regulatory disclaimer
FormulaNorth helps organize cosmetic formulation, label, costing, and CNF preparation information. It is not legal or regulatory advice and does not replace Health Canada guidance, professional regulatory review, or the maker's responsibility to verify product compliance before sale.
Selling in Canada?
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