soap (animal and petroleum bi-product free)



  • "brewers" thermometer, to measure in the range of 35-37°C or 95-98°F
  • kitchen scales
  • large wooden spoon
  • wooden stick (my scottish "spurtle" is perfect)
  • shoe box lined with plastic garbage bags, and with a lid
  • large glass jar with screw-on lid
  • saucepan
  • plastic bucket or large bowl


Try to find cheap/low quality olive and coconut oils. Try italian and indian grocers, who stock a range of grades. "copha" is hydrogenated coconut oil, and I have not seen in on sale in the US. I once tried using "crisco" which is partically hydrogenated vegetable oil, and it didn't mix.

Caustic soda also called sodium hydroxide is available from supermarkets and hardware stores. It is used to clean drain-pipes and so on. it is quite dangerous if mis-used; contact with the skin causes burns. You want the dry power or granulated form - not a liquid. It was originally produced by dripping water through coals, but who knows how commercial caustic is produced now. Legend has it that soap was discovered when animals were sacrificed on a big fire, the animal fat and caustic reacted to give a crude form of soap. Not very vegan.

Try and keep your soap-making utensils only for making soap.

Keep in mind that making soap is a chemical process, and so requires much more care and precision with weights and temperatures than cooking a cake.


step 1: pierce two holes in the lid of the glass jar. Weigh out the water in the large glass jar. Weigh the caustic carefully and sprinkle it into the water, stiring carefully with wooden stick. You may wish to wear gloves during this process, eye protection, and old clothes! NEVER add water to caustic. The reaction causes a lot of heat to be generated.

Leave the caustic mixture to cool for several hours.

step 2: melt the oils together over a very low heat in saucepan, and pour into plastic bucket or enamel pot. Get the shoe-box ready, and select an essential oil to add at the very end if you wish. You must get both the oil and the caustic mixtures at 35-37 °C or 95-98 °F BEFORE you can mix them. With practice this is easy, but the first time it can be quite a challenge. Start with the oil and place it in a sink of hot or cold water, until it reached the correct temperature. The oil will hold its temperature better than the caustic. Then bring the caustic to the right temperature again using hot/cold water in the sink.

Screw on the lid to the caustic, and while stiring the oils slowly add the caustic in a steady stream through a hole in the lid, resting the jar on the side of the pot/bucket. It may take 1-2 minutes to add all the caustic. Continue stiring a a constant rate, don't scrape the sides. You should notice the mixture turning from yellow to murky opaque and resembling "pea soup". The caustic is reacting with the oil molecules, and changing one of their ends chemically.

Stir for at least half an hour, and test to see that a "figure 8" drawn on the surface by dripping some mixture off the spoon holds its form for a few moments.

Add several drops of essential oil (such as tea-tree, lavender, eucalyptus, sandlewood) and pour into the shoe-box, cover and leave in a warm place for 24 hours, covering the box with blankets. The mixture will continue to react (and produce its own warmth) until is solidifies. Resist the temptation to peak during this time.

After 24 hours, take the large block and sit it on thick newspapers to air for a few weeks. After a few days is will become more and more solid, and you can cut it into bars but continue to air them. Sometimes a layer of liquid forms on the surface. This is usually due to incorrect temperatures, and will improve with practice! discard this substance, it is very caustic.

When using the soap, be sure not to leave it sitting in water, like next to the sink and in the shower. Get some soap holders with good drainage. Enjoy!


Fat and oil molecules are very long and repell water, but when you react them with sodium hydroxide (caustic soda), one of the ends of these long molecules changes and its attracted to water. This gives a new molecule where one end of it mixes with water, and the other end is attracted to dirt and oils just as before. This is how you make soap. To increase the chances of all the molecules reacting make sure you mix at the right temperature, and also stiring the reactive mixture with put more molecules in contact with each other so increase the chances of reactions. In commercial soap-making (which uses petroleum and animal derived oils) other chemicals (enzymes) are added which help speed up the reaction.