Manufacture of soap using the cold method


  1. a pot in which we dissolve the oil phase,
  2. glass vessel for caustic soda (sodium hydroxide NaOH) and distilled water,
  3. blender,
  4. kitchen scales or measuring jug,
  5. two kitchen thermometers or a pyrometer (measures the temperature with a laser beam – non-contact).
  6. gloves, apron and safety glasses,
  7. a mould for soap – it can be an empty juice carton or plastic yoghurt cup.

The most commonly used proportion to make soap by the cold method is the one in which: water constitutes about 20% of all ingredients, fats about 70%, and caustic soda – about 10% of the soap mass.

To make 1000g of soap we need:

  • 200g of distilled water
  • 700g of fats, these can be various types of oils: rapeseed, castor, olive, avocado or almond oil.
  • 100g of NaOH Sodium Hydroxide

We will start the preparation of the soap by making a water phase i.e. combination of water and NaOH Sodium Hydroxide

Pour 200g of distilled water into one dish, and add 100g of sodium hydroxide to the other. This substance is highly corrosive, which is why we protect the body with gloves, an apron and glasses. Also avoid inhaling the vapours that will be released when the caustic soda dissolves in the water. Remember, always pour sodium hydroxide into water, not the other way around! Lastly, leave it to cool.

Oil phase: put all oils and butters, e.g. shea, cocoa, coconut, etc. in a pot, melt fats and heat to 45 degrees Celsius on low heat. We measure the water and oil phase with two kitchen thermometers or a pyrometer. Both should have similar temperatures, around 45 degrees Celsius.

Then we make the water phase and with a thin stream, we pour it into the oil phase. The combined phases are mixed first with a spoon and then with a blender. The mixing operation should be performed several times for approx. 2 minutes each time. After about 5-10 minutes, the liquid substance formed from the combination of water and oil should start to thicken. Solidification indicates that the saponification process has begun. When the mixture has a milk pudding-like consistency, it is the perfect moment to add the remaining ingredients: fragrance oils, dried flowers, peeling poppy seeds, clays or cosmetic dyes.

The resulting mass is poured into the mould. The filled mould should be covered with a cloth or towel and left for one day. After 24 hours we check whether the soap is hard. If not, leave it for another 24h but this time without a cover. After cutting the mould made of an empty juice carton or yoghurt cup, we pull out the soap. If the soap should be cut into smaller cubes, a ceramic knife or an ordinary knife immersed in warm water will facilitate the task. We leave the soap bars for 3 to 5 weeks. The longer the aging process, the harder and milder the soap will be.

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