It is possible to make soap without modern chemicals , indeed soap in this form has been in use for over two thousand years , so it is a method worth knowing .
As mentioned earlier the lye is obtained by leaching wood ash with water, the only wood ash of use for this is the white powdery ash left after the black charcoal is burned off . Gather enough ash to fill a four or five litre container , a fly-wire sieve can be used to remove any unburnt charcoal , then drill or pierce small ( say 2-4 mm ) holes in the bottom of the container to let the water through . Then place your ash in the leaching container and pour through it about four litres of water , the water may be run through this procedure a number of times to increase the pickup .
The lye solution should now be concentrated by boiling or just allowing it to evaporate down to about 250 to 300 mls . The concentration can be checked by putting an egg or potato into the lye , if they float it is concentrated enough .
To make the soap put into your soapmaking container half a cup of lye solution for each cup of fats or oils , then add the fats and boil the mix until it becomes thick , rubbery and foamy . The container is then removed from the heat and allowed to cool . The effectiveness of the soap improves with age so it should be stored for a month before use ,the soap may be stored in containers made from wood , steel , iron , glass or clay . The soap made by this method is a soft potassium soap and will not harden like the harder sodium soaps made with caustic soda ( sodium hydroxide ) it will , however , clean just as well .