Many people are beginning to experience the rewards of making their own homemade bubble bath. The base ingredient for bubble bath is liquid soap, and liquid Castile soap is most commonly used for this purpose. ("Castile soap" is a term which originally referred to soap made from olive oil, but it is now used to refer to pretty much any soap made from vegetable oil as opposed to animal fats.) You can purchase liquid Castile soap, or if you are feeling up to a slight challenge, you can experience the satisfaction of making your own liquid soap.
Liquid Castile soap can be made via either the cold-process or hot-process method. Many soap-makers prefer the hot process method because it is much quicker, and after three to four hours of "cooking" the soap in a crock pot, it is completely saponified, whereas the cold-process method requires the soap to be cured for six to eight weeks before the saponification process is complete. (Saponification is the process by which lye chemically reacts with water and oil to make soap.)
Of the two varieties of lye, potassium hydroxide lye is favored by most soap-makers for liquid soap, because the soap yielded by this compound is softer and easier to melt than soap made with sodium hydroxide lye.
To make liquid Castile soap via the hot-process method, mix the oils and lye just as you would if you were making cold-process soap, and blend until the mixture reaches trace. Be patient - this may take a while, and when trace is reached the batter may be thinner than it normally would be. This is a normal result of using the potassium hydroxide lye, instead of sodium hydroxide.
When the soap batter does reach trace, start cooking it in a double-boiler or crock pot, over low to medium heat, for three to four hours. The mixture will go through many stages, during the last of which is will be translucent and creamy.
To see if the liquid soap is done, mix one ounce of the soap with two ounces of boiling water. If the mixture is clear, or only slightly cloudy, then the soap is done, but if it is milky or very cloudy, the soap needs to cook longer. (If cooking longer doesn't solve the problem, then one of your ingredients may have been measured improperly prior to starting the process.)
Consider adding a preservative, such as grapefruit seed extract or vitamin E, to your liquid soap when it is done cooking, and prior to packaging it, as liquid soap is more prone to spoilage than bar soap. At this point, the liquid soap is ready to be incorporated into your liquid bubble bath recipe.
Buying ready-made liquid Castile soap, such as Dr. Bronner's, is certainly an option, and is often chosen by people who aren't inclined to make their own for whatever reason.
However, if you do choose to make your own liquid bubble bath base from scratch, you will enjoy a sense of accomplishment, and have a greater degree of control over your ingredients and the customization of your soap.
