Soapmaking
Practical Action
If a big barrel is not available, or smaller amounts of soap are to be made, a porcelain bowl or
plastic bucket can be used. Fill the bucket with ashes and add boiling water, stirring to wet
the ashes. Add more ashes to fill the bucket to the top, add more water and stir again. Let
the ashes stand for 12 - 24 hours, or until the liquid is clear, then carefully pour off the clear
lye.
The longer the water stands before being drawn off, the stronger the lye will be. Usually a few
hours will be enough. Lye that is able to cause a fresh egg to float can be used as a standard
strength for soap-making. The strength of the lye does not need to always be the same,
because it combines with the fat in a fixed proportion. If weak lye is used, more lye can be
added during the process until all the fat is made into soap (saponified).
How to make potash
Potash is made by boiling down the lye water in a heavy iron kettle. After the water is driven
off, a dark, dry residue remains which is known as known as 'black salts'. This is then heated
until it melts and the black impurities are burned away to leave a greyish-white substance.
This is potash. It can be stored for future soapmaking in a moisture-proof pot to prevent it
absorbing water from the air.
How to make soda lye and caustic soda
Mix 1 part quicklime with 3 parts water to make a liquid that has the consistency of cream.
Dissolve 3 parts sal soda in 5 parts boiling water, and add the lime cream, stirring vigorously.
Allow the mixture to boil until the ingredients are thoroughly mixed. Then allow it to cool and
settle, and pour off the lye. Discard the dregs in the bottom. Caustic soda is produced by
boiling down the lye until the water is evaporated and a dry, white residue is left in the kettle.
Most commercial lye is caustic soda, and it can be bought and substituted for homemade lye
to save time. Lye is supplied in tins and the lid should be kept tightly fitted to stop the lye
absorbing water from the air and forming a solid lump.
Care with lye, potash and caustic soda
You should always take precautions when handling these materials as they are dangerous. Be
especially careful when adding them to cold water, when stirring lye water, and when pouring
the liquid soap into moulds. Lye produces harmful fumes, so stand back and avert your head
while the lye is dissolving. Do not breathe lye fumes. Use rubber gloves and plastic safety
goggles. You should also wear an apron or overalls to protect your clothes. If lye splashes
onto the skin or into your eyes, wash it off immediately with plenty of cold water.
When lye is added to water the chemical reaction quickly heats the water. Never add lye to
hot water because it can boil over and scald your skin. Never add water to lye because it
could react violently and splash over you. Always add the lye to the water in small quantities
at a time.
How to prepare tallow
Cut up beef suet (fat), mutton fat or pork scraps and heat them over a low heat. Strain the
melted fat through a coarse cloth, and squeeze as much fat as possible out of the scraps.
Clean the melted fat by boiling it in water. Use twice as much water as fat, add a tablespoon
of salt per 5 kg fat, and boil for ten minutes, stirring thoroughly all the time. Allow it to cool
and form a hard cake of fat on top of the water. Lift off the cake of fat and scrape the
underside clean. This is then ready to store or use in a soap recipe.
How to prepare oil
Vegetable oils can be extracted from oilseeds, nuts or some types of fruit (see the separate
Technical Brief on 'Oil Extraction'). Oil can be used alone or mixed with fat or other types of
oil. Note: solid fats and 'saturated' oils (coconut, oil palm, palm kernel) are more suitable for
soap making. 'Unsaturated' oils (e.g. safflower, sunflower) may produce soap that is too soft if
used alone (see Table 2) and are not recommended.
Soap making
There are two types of soap: soft soap and hard soap. Soft soap can be made using either a
cold process or a hot process, but hard soap can only be made using a hot process. To make
2