Making soap

Procedure

• Prepare the sodium hydroxide solution in water: Let it rest and cool for about 15 minutes.
• Add the oil and stir by hand or with the mixer (starting at low speed). It should be stirred until we achieve a trace structure (when the mixture leaves a mark when we pass the spoon or the mixer, about 20 minutes).
• Add the essential oils or dyes.
• Pour the homogeneous mixture into molds and let it rest in a cool place. Wait for 2 weeks, then unmold and cut if necessary.

Theoretical explanation

In this experiment the saponification reaction is uncovered. That is to say, the fatty acids from the oil, which are slightly acidic, react with the sodium hydroxide, which has a strongly basic character. This reaction results in a slightly alkaline salt called soap and a three-hydroxyl group alcohol, glycerin.

This reaction can be carried out either hot or cold, but it has been found that more reproducible results are obtained by doing it cold, besides being safer. Once unmolded and cut, the soap still needs to be left to rest for about 4-6 weeks.

By using colorants or dyes, we can achieve soap of different colors. We can also add rosemary, thyme, rose petals, or anything else that makes our soap special… at least for us!

Other oils can be used. Some examples are: Almond oil, apricot kernel oil, avocado oil, borage oil, calendula oil, rapeseed oil, castor oil, coconut oil, corn oil, evening primrose oil, hazelnut oil, hemp oil, jojoba oil, neem oil, palm oil, peanut oil, pumpkin seed oil, sesame oil, soybean oil, sunflower seed oil, wheat germ oil, macadamia nut oil, cocoa butter, lard, etc.