Liquid Soap Recipe
A liquid soap recipe made with potassium hydroxide (KOH): a soap paste you dilute into liquid hand soap.
Why this recipe works
Liquid soap uses KOH instead of NaOH. You cook it into a thick paste, then dilute the paste with water to the thickness you want. A low 3% superfat helps keep it clear.
Ingredients
| Ingredient | % | Grams | Ounces |
|---|---|---|---|
| Coconut Oil (76°) | 40% | 400 g | 12.8 oz |
| Olive Oil | 40% | 400 g | 12.8 oz |
| Castor Oil | 20% | 200 g | 6.4 oz |
| Potassium hydroxide (KOH, 90%) | 231.5 g | 7.4 oz | |
| Distilled water | 463 g | 14.8 oz |
Amounts are for 1000 g (or 32 oz) of oils, a batch of about 1695 g before curing. Water is 2:1 to lye by weight.
Method
- Put on gloves and eye protection and clear the work area.
- Weigh the water into a heat-safe jug. Weigh the lye separately, then slowly add the lye to the water, never the other way round. Stir until dissolved.
- Melt the oils in a slow cooker on low.
- Add the lye solution to the oils and stick blend to trace.
- Cover and cook on low, stirring every 15 minutes, until the soap looks like translucent mashed potato or petroleum jelly.
- Once the paste is fully cooked (a small amount dissolves clear in hot water), dilute it with hot distilled water, a little at a time, until it is the thickness you want.
Tips
- The lye amounts assume 90% pure KOH, the standard grade.
- Many makers use more water than shown (up to 3 parts water to 1 part KOH) for an easier-to-stir paste.
- Dilute the finished paste with roughly 1.5–2.5 times its weight in hot distilled water, adding it gradually.
⚠️ Lye safety
Lye is caustic. Wear gloves and eye protection, work in a ventilated room, keep children and pets away, and always add lye to water. Always run any recipe through a lye calculator before making it, especially if you change an oil.
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