Making soap is dangerous and so much fun: everyone should do it
Making soap was one of my best memories of sophomore year at Oxford - we made it a couple more times afterward - but it's been a while. Ms. Harmon and I decided to do it again this year FOR FUN AND PROFIT. This post is to show you how we did it, a very little about the chemistry behind it and why it is such fun.
Single-batch Soap Recipe
75g DI water
29.6 g sodium hydroxide (NaOH, lye)
80g coconut oil
40g olive oil
80g palm oil
Steps to Making Soap ...
1. Weigh out the water in 250 ml beakers
2. Weigh out the 29.6 g of NaOH; slowly mix with the water
Note: The dissolving of sodium hydroxide is highly exothermic (releases heat). Therefore, dumping in so much at once makes the water SOO HOT!! The heat is actually needed for making the soap properly.
Warning: NaOH is extremely basic and this recipe essentially makes a 10M basic solution, which is highly corrosive, will eat through clothes and cause bad chemical burns if exposed to skin. Make sure to wear goggles, lab coats and gloves at all times. But what's fun without a little danger?
3. Melt, measure and weigh out the appropriate oils
4. Slowly mix the oil and the NaOH solution, stirring with spatula
5. Mix the oil/NaOH syrup with a hand blender! OH YES!
Do not try this at home ...
6. Pour finished sludge of soap into a bin lined with wax paper
Saponification: What Chemistry Is Happening?
On glycerol: The glycerol is actually a nice moisturizer, so leaving it in does no harm. Ms. Harmon notes that some soaps are sold as "glycerin soap," as if adding glycerin to soap is in some way novel. Don't let them fool you - it's not. Only, apparently for a lot of soap making, the glycerin is separated from the soap and used for other things or sold separately. I'm wondering if this is one reason why homemade soap is so great.