Soapmaking
Practical Action
any soap it is necessary to dilute the lye, mix it with the fat or oil, and stir the mixture until
saponification takes place. In the processes described below, the word 'fat' is used to mean
either fat or oil. The cold process may require several days or even months, depending upon
the strength and purity of the ingredients, whereas the hot process takes place within a few
minutes to a few hours.
Dispose of soap-making wastes carefully outside the house. Do not put them in the drain.
Fats Oils
Goat fat
Canola
Lanolin
Coconut
Lard Cottonseed
Mutton fat
Palm
Pork fat
Palm kernel
Suet
Soybean
Tallow
Table 1: Types of fats and oils used in soapmaking
Soft soap
Cold process
A simple recipe for soft soap uses 12 kg of fat, 9 kg of potash and 26 litres of water. Dissolve
the potash in the water and add it to the fat in a wooden tub or barrel. For the next 3 days,
stir it vigorously for about 3 minutes several times a day, using a long wooden stick or paddle.
Keep the paddle in the mixture to prevent anyone accidentally touching it and being burned.
In a month or so the soap is free from lumps and has a uniform jelly-like consistency. When
stirred it has a silky lustre and trails off the paddle in slender threads. Then the soap is ready
to use and should be kept in a covered container.
Boiling process
Soft soap is also made by boiling diluted lye with fat until saponification takes place. Using
the same amounts as above, put the fat into a soap kettle, add sufficient lye to melt the fat
and heat it without burning. The froth that forms as the mixture cooks is caused by excess
water, and the soap must be heated until the excess water evaporates. Continue to heat and
add more lye until all the fat is saponified. Beat the froth with the paddle and when it ceases
to rise, the soap falls lower in the kettle and takes on a darker colour. White bubbles appear
on the surface, making a peculiar sound (the soap is said to be 'talking'). The thick liquid
then becomes turbid and falls from the paddle with a shining lustre. Further lye should then
be added at regular intervals until the liquid becomes a uniformly clear slime. The soap is
fully saponified when it is thick and creamy, with a slightly slimy texture. After cooling, it
does not harden and is ready to use.
To test whether the soap is properly made, put a few drops from the middle of the kettle onto
a plate to cool. If it remains clear when cool it is ready. However, if there is not enough lye
the drop of soap is weak and grey. If the deficiency is not so great, there may be a grey
margin around the outside of the drop. If too much lye has been added, a grey skin will
spread over the whole drop. It will not be sticky, but can be slid along the plate while wet. In
this case the soap is overdone and more fat must be added.
Hard soap
The method for making hard soap is similar to that for making soft soap by the boiling
process, but with additional steps to separate water, glycerine, excess alkali and other
impurities from the soap. The method requires three kettles: two small kettles to hold the lye
and the fat, and one large enough to contain both ingredients without boiling over.
Put the clean fat in a small kettle with enough water or weak lye to prevent burning, and raise
the temperature to boiling. Put the diluted lye in the other small kettle and heat it to boiling.
Heat the large kettle, and ladle in about one quarter of the melted fat. Add an equal amount
of the hot lye, stirring the mixture constantly. Continue this way, with one person ladling and
another stirring, until about two-thirds of the fat and lye have been thoroughly mixed
together.
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