Interesting read about colonial soapmaking:  Enjoy!

Boiling the Lye

Here is a quote from Clifton Johnson's book Highways and Byways of the Mississippi Valley:

"I stopped at a farmhouse to talk with a sunbonneted white woman who was making soft soap in the yard. She had a fire with a great black kettle over it and said she was 'bilin' the lye. It has to bile slow all the morning,' she continued, 'till it's very strong. Then I put in the fat I've saved --- trimmin's of meat sich as we don't eat, pork rinds, and the cracklin's that we have left when we are trying out lard. After the fat is in I have to stir it every little while with a paddle and be careful not to have too big a fire, or it will bile over. So it simmers along till four or five o'clock and is done; and when it's stood to cool over night I dip it out into a flour barrel. If the soap is all right it's thick like jelly, and I'd much rather have it than the soap you buy. What I make in this kittle will run me a year."                                     

Soft and Hard Soap

Soap made with wood ash lye does not make a hard soap but only a soft soap. When the fire was put out and the soap mixture was allowed to cool, the next day revealed a brown jelly like substance that felt slippery to the touch, made foam when mixed with water, and cleaned. This is the soft soap the colonists had done all their hard to produce. The soft soap was then poured into a wooden barrel and ladled out with a wooden dipper when needed.

To make hard soap, common salt was thrown in at the end of the boiling. If this was done a hard cake of soap formed in a layer at the top of the pot. As common salt was expensive and hard to get, it was not usually wasted to make hard soap. Common salt was more valuable to give to the livestock and the preserving of foods. Soft soap worked just as well as hard and for these reasons the colonists, making their own soap, did not make hard soap bars.

In towns and cities where there were soap makers making soap for sale, the soap would be converted to the hard soap by the addition of salt. As hard bars it would be easier to store and transport. Hard bars produced by the soap maker were often scented with oils such as lavender, wintergreen, or caraway and were sold as toilet soap to persons living in the cities or towns.

Hard soap was not cut into small bars and wrapped as soap is sold today. Soap made by the soap makers was poured into large wooden frames and removed when cooled and hard.

The amount of soap a customer wanted was cut from the large bar. Soap was sold usually by the pound. Small wrapped bars were not available until the middle of the 19th century.

Another thought to remember is the soap making procedure described is not only how the homesteading colonial women made their soap. Soap making was generally a task the women did. This was essentially the method used by all soap makers of the period. Soap making was always considered one of the most difficult jobs on the farm or homestead.

http://www.alcasoft.com/soapfact/history.html