I get a lot of questions about soap, something most people use daily and don't really think much about. What is soap really? The simple answer is a combination of fats and lye. When combined together they go through a chemical process called saponification. When cured and the saponification process is complete you have soap and no longer a simple fat and lye solution.
Lye by itself is alkaline (having a ph over 7) and can cause chemical burns and must be handled carefully during the soap making process. Lye is combined with liquid and brought down to temperature before being added to the fats. It is usually combined with water but, you could use milk or herbal tea as well. When added to liquid the temperature rises dramatically. Some liquids will boil over, others will be scorched so they need to be frozen or chilled before the lye is added.
The fats can be animal or vegetable, solid or liquid. Tallow or lard were traditionally used but, olive, coconut, shortening and any other plant based oil will work as well. Butters as in cocoa butter and shea butter can be used. All of these need to be in liquid form before the lye solution is added. Coconut is used often as it naturally produces lather. Lather is not needed for a soap to be effective.
There are several processes to make soap, cold, hot and melt and pour. I use a cold process method. It is soap making method where the starting ingredients of lye solution and a blend of oils/fats/butters are separately brought to their desired temperatures, mixed together, and allowed to react without additional heat.
Hot process soap making is a method where the soap is made as in cold process method, but then further cooked using additional heat. The advantage to this method is that it doesn't need to sit and cure for weeks like cold process soap making. Melt and Pour soap making is where the soap base is commercially produced and the saponification process is complete. This pre-made soap base is formulated to withstand remelting so that the soap sets up immediately with no curing or drying time.
Much of what is found in the soap aisle of grocery stores is actually detergent and not soap. They are harsher on the skin.
Detergent is defined as any group of synthetic, organic, liquid or water-soluble cleaning agents that, unlike soap, are not prepared from fats and oils, are not-inactivated by hard water, and have wetting-agent and emulsifying-agent properties.
At the time of trace, the point where the fats and lye have been combined and are starting to set, you can add others ingredients if you like. This is the time you would add colorants, fragrance, clay, exfoliates or herbs.
Some questions to ask your local soap maker.
What process do you use?
What ingredients do you use? These should be listed on the label. Some soap makers just list fragrance and do not break it down. I get this as protecting their propitiatory blend but, it makes me wonder as to the quality of the ingredients. Fragrance oils can have up to 15 unidentified and synthetic ingredients in them. I will not use them myself.
How do you color your soap? There are many natural ways of coloring soap. I use herbs and clay to color mine. There are natural micas that can be used; I just haven't played with them yet.
Why do you make soap? I find people's stories fascinating and they tell a lot about their product.