The Dermatologist’s Secret to Soap

The Dermatologist’s Secret to Soap

soap

Bars of my hand-made soap

One of the advantages of having excelled in college physical and organic chemistry class is that the fundamental knowledge of how the world works stays with you forever in every aspect of your life. I recently attended a soap-making class and finally made some practical use out of theoretical chemical equations that were still lingering in my subconsciousness. It also really made me think about product creation from a medical standpoint. After all, even though dermatologists constantly prescribe various personal products and critique every skincare ingredient, I can’t say how many dermatologists actually create their personal products from scratch.

Soaps can be hand-made or commercially made. The processes are similar, but different enough for me to recommend hand-made soaps over any commercial soap. The common reaction is saponification, whereby sodium hydroxide (also known as lye) is mixed with any number of fatty acids types to produce “soap” and glycerin. In commercial soaps, the fatty acid used is often animal fat and the glycerin, which is a prime ingredient of skin moisturizers, is removed to manufacture moisturizers. In hand-made soaps, you can control the fatty acid type (I recommend a vegetable oil such as olive oil) and retain the hydrating glycerin.

After the saponification reaction comes the fun part for hand-made soaps, whereby you add any number of fragrant essential oils and natural exfoliants. I made my soaps with a permutation of lavender oil, orange oil, and peppermint oil. I chose raw poppy seeds and oatmeal grains as the exfoliant. Unlike commercial soaps, I avoided addition of synthetic dyes, synthetic fragrance mixes, and chemical preservatives.

The last part of hand-making soap is the casting of the soap into a mold. In commercial processes, sodium chloride (salt) is added to precipitate the soap into curds which are then collected and compressed into various shapes. In hand-made soaps, you pour the well-mixed solution into a mold and let it solidify without the addition of salt, which can be harsh to sensitive skin.

After the hand-made soap is placed into a mold, it takes several weeks for the soap to cure. On a chemical level, the saponification process is slowly reaching completion. But alas, good things come to those who wait.

So hand-made soaps simply involve a basic understanding of the saponification reaction, but don’t attempt to repeat this at home without formal instruction. Sodium hydroxide (lye) is extremely toxic and the chemical reaction is extremely exothermic (heat generating).  Proper precautions and  protective gear is required. However, at least you now understand what you’re cleaning your skin with on an everyday basis.   Like all prized consumer goods, the best soaps are still hand-made.

Dr. Julia Tzu

Dr. Julia Tzu is a double board certified dermatologist who specializes in Mohs and reconstructive skin surgery, laser surgery, and cosmetic dermatology. She is one very few dermatologists in the world who has devoted additional years of formalized fellowship training in both Mohs surgery as well as dermatopathology, making her amongst the most highly trained and elite dermatologists.

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