Lost Skills: Soapmaking

Soapmaking, as a hobby, tends to get either the enthusiastic interest of people who are into homesteading and do-it-yourself make-your-own hobbies, or half-amused references to the 1994 Fight Club scenes about stealing medical waste from liposuction operations and turning the fat into soap to then sell back to the wealthy customers of those same cosmetic surgery clinics.

That is possible, by the way. The making of soap from human (or, more usually) other animal fat. Lard (beef fat) and tallow (sheep or lamb fat) are traditional ingredients for soapmaking, and make a nice, hard soap with a good lather. One assumes that human fat would do the same, although I’m not going to be testing the theory.

Soap is the result of a reasonably complex chemical reaction between a fat or oil and either sodium hydroxide (NaOH) or potassium hydroxide (KOH), both of which are commonly called ‘lye‘, and can be extracted from wood ash by soaking it in water. Be aware that either sort of lye is incredibly dangerous, as it’s a strong alkali, and it will dissolve your skin if you get it on you; BE CAREFUL.

To make soap – I’ve done it before, and as I’m almost out of the delightful soap that I made last time, I’m going to be doing it again this week – you need a recipe. You cannot just modify an existing recipe without doing some significant calculations, as each type of oil or fat has a slightly different reaction with the lye, and if you substitute one oil with another you may end up with un-reacted lye in your soap, and therefore soap which dissolves skin instead of just dissolving grease and dirt off of skin.

The process, for pretty much any recipe, is as follows. You will need an immersion blender or stick mixer that you don’t mind using for soap (afterwards it will probably forever smell of the essential oils you use, since plastic absorbs scents sometimes.) You can stir the soap by hand if you prefer, in which case expect to be stirring for at least half an hour and up to 2 or 3 hours.

  • Heat the water to between 40 and 45 degrees C.
  • In a nonreactive bowl or jug, add the sodium hydroxide to the water, stirring until it has dissolved. Do this in a well ventilated area, and wear safety glasses.
  • Leave the water/sodium hydroxide solution to one side, checking the temperature and stirring regularly until it reaches 40 – 45 degrees C. This may take up to 2 or 3 hours.
  • If the coconut oil is solid, heat gently until it melts, then cool to room temperature. Carefully weigh all the oils (except the essential oils) and stir together.
  • Very carefully and slowly pour the sodium hydroxide/water solution into the oils.
  • Use a long handled spoon (or paint stirrer), slowly and carefully stir the lye solution into the oils/fats. When your soap mix turns completely opaque, set aside your stirring spoon, and grab the stick blender.
  • Place your stick blender as close to the bottom of the soap pot as you can and then turn it on. Slowly move your stick blender around the soap pot for about 2-5 minutes, then turn it of and stir manually with it off for a couple of minutes. Alternate the on and off stirring technique until trace to avoid overheating your stick blender. You should be wearing gloves and safety glasses in case the soap splashes; at this stage it is very alkaline and dangerous to get into your eyes.
  • Stir until the soap mixture thickens to the consistency of a moderately thick custard (‘trace’ stage) and turns creamy and opaque.
  • Add essential oils and stir the mixture thoroughly by hand using your long spoon or paint stirrer.
  • Pour the soap into the mould, tapping the moulds gently to make the mixture level. Silicone mouls are the easiest to use, but a cardboard milk carton that you’ve cut the top off of makes a pretty good mould.
  • Leave the soap alone somewhere it will not be disturbed for at least 24 hours. It may take up to a week, depending on the soap and the ambient humidity before your soap is firm enough to remove from the mould. It may be a little oily to the touch. But it should be the same texture throughout. It will resemble a cheese, like monterey jack, and have a similar texture.
  • Use a sharp knife or cheese wire to cut the soap into useable blocks. Lay the soap bars out on a piece of cardboard or wooden surface and cover with an old towel. Then leave them for four weeks before using them to allow the sodium hydroxide fully react with the oil and the soap to harden and cure.

If your soap goes cold during the first 24 hours or turns to mush, you probably lost the saponification process. There can be a lot of reasons for this. Your weights of oils, or lye may have been off causing a bad batch, or your temperature was not high enough with the fats and it just lost temperature. If you’re sure your weighing was correct, then pour it into your soap pot, put it on the stove. Heat it while stirring constantly. When it reaches 54 degrees C, remove from heat and pour back into a fresh mould; this may or may not save it, but it has a good chance if your weighing was accurate.

And now for the exciting part – the recipe!

This is my basic supermarket soap recipe, using readily available oils you can get from most supermarkets in Australia. It’s vegan-friendly (no lard or tallow), and it produces a gentle, creamy soap with a good lather, which can also be used as a shampoo bar (do the last rinse of your with diluted vinegar to keep your hair at a healthy, mildly acidic pH – seriously, this is very good for your hair no matter what shampoo you use).

  • 180 g water
  • 63 g NaOH (sodium hydroxide) powder, available from Bunnings
  • 100 g coconut oil
  • 150 g olive oil
  • 150 g rice bran oil
  • 75 g sunflower oil
  • 20 g essential oils for scent

There are dozens of recipe available online, if you want to try something a bit more adventurous. Try some of these sites:

Happy soaping! 🙂