Natural homemade castile soap
A soap with more than fifty per cent olive oil —
the simplest recipe and what to expect from it
The term castile soap refers to a soap that contains more than fifty per cent olive oil. Olive oil is unique in that it can make up the oil part of a soap entirely on its own.
That comes at a cost — it does not foam. Which is why the recipe includes a little castor oil, to create the bubbles we all enjoy.
Everything behind these numbers — lye, the trace, the discount and safety — is explained in the guide.
The recipe
Ingredients:
- Olive oil — 855 g / 30.16 oz
- Castor oil — 45 g / 1.58 oz
- Lye, sodium hydroxide (NaOH) — 115 g / 4.05 oz
- Distilled water — 207 g / 7.30 oz
- Lye discount — five per cent
The castor oil is only five per cent of the total oil, which is also the maximum recommended. And that much is enough to get the soap lathering.
Weigh the ingredients
Weigh the distilled water
Weigh 207 g / 7.30 oz of distilled water into a bowl.
The amount is small because the lye was multiplied by 1.8 rather than by three. With a single colour olive oil soap that is allowed, and it shortens the curing.
Weigh the lye
Weigh 115 g / 4.05 oz of sodium hydroxide into a separate bowl.
Goggles, mask and gloves go on before you open the lye.
Weigh the oils
Weigh 855 g of olive oil and 45 g of castor oil into the pot, so 900 g in total.
Zero the scales between the two oils.
Make the soap
Pour the lye into the water
Slowly pour the lye into the water. Never the other way around, as it can provoke a violent reaction. Work near an open window and keep your face away from the pot and the fumes.
Stir a few times with a plastic or stainless steel spoon until the lye dissolves in the water.
Match the temperatures
Let the lye solution cool to between 30 and 50 °C / 86 and 122 °F, and heat the oils to roughly the same temperature. A difference of up to eight degrees is fine.
Combine and blend to a trace
Pour the hot lye solution into the oils. Blend without moving the blender, then switch it off and stir by hand. Repeat until you reach the trace — about five minutes.
Pour the soap into the mould
Pour the soap into the silicone mould and smooth the top with a spatula.
Cover the soap and leave it
From here there are two options:
- Cover the soap with cardboard and a towel and leave it for at least twenty four hours, though forty eight is better.
- Put the uncovered mould into a previously heated, now switched off oven at 50 °C / 122 °F and leave it for twenty four hours.
Cut the soap into bars
Take the soap out of the silicone mould and cut it with a knife into slices 2 cm / 1 inch wide.
Let the soap cure
Set the bars on a rack, cover them with a cloth, and leave them somewhere cold and dark for at least a month. For the best result, give them three months.
Olive oil cures more slowly than other oils, so with this soap the waiting pays off most: after three months it lathers better, it is less abrasive, and it lasts longer in the shower.
Where to go next
Once this recipe feels familiar, colour and herbs are the next step: the rosemary soap with spirulina and the coffee and cocoa soap. A different ending altogether belongs to the liquid soap.
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