There are so many different types of "soap" on the market. It can be confusing for the consumer to understand what the different terms mean. So, here is a quick and easy primer on popular soaps that are available.
Soap- The term "soap" technically means the result of a chemical reaction between oils/ fats and a caustic substance like sodium hydroxide. The result of this reaction is an agent that cleans and forms a lather. Soap makes water wetter. The way it works is that each soap molecule has a "head" and a "tail". The head of the soap molecule loves water and attaches itself to water molecules while the tail of the soap molecule loves oils and will attach itself to an oil molecule. So oils are flushed away with the water. Soap also disturbs the surface tension of the water. All of this makes it easier to wash away dirt and grime.
Making Cold Process Soap
Cold Process- This is a process by which soap is made that requires no additional heat. This is the most basic form of soap. Most of the soaps at Bean Tree Soap are made by this method. Oils are melted and added to lye and then blended. Then they are allowed to undergo a chemical process on their own. The soap has a minimum cure time of 3 weeks. During this 3 weeks, the soap will complete the chemical reaction and lose water, making it a harder bar. The resulting soap is hard and opaque. Cold process bars have a long shelf life however, over time some of the additives like essential oils or colorants may fade. Depending on ingredients, these are the most natural forms of soap available on the market.
Soap undergoing saponification in molds.
Hot Process- Like cold process soap, hot process soap starts out with melted oils and lye. The two are blended together but unlike cold process soap, hot process soap undergoes a cooking stage where heat is added. This acts as a catalyst for the chemical process of saponification. The resulting bars of soap are a bit different in appearance but are completely cured once they are hardened in the mold. These soaps do not have a long cure time.
The Cure- for soapers at least.
One of the many cool things possible with glycerin soap, owl soaps.
Glycerin- Technically, glycerin is a by-product of soap making. Every bar of handmade soap will naturally contain glycerin. However, there are soaps which are commonly referred to as "glycerin soap". These soaps are usually transparent. Some have detergents and some are true soap. These soaps are a bit more processed than the previously explained soaps and typically are made from a base. They are very gentle on fragrances and easy to color as the additives are not exposed to the chemical reaction of soap making. Often, these soaps are quite beautiful and allow for more creative and intricate designs as well as some fragrances that are not suitable for cold process soaps. The high glycerin content of these soaps make them "sweat" if they are left in a humid environment. The glycerin soaps made by Bean Tree Soap are packaged in plastic wrap with a sticker label. It is very important with these soaps that they not be left in water.
Superfatted- This is a term used when a soap has added extra oils or fats so that not all of them react with the lye. This is also called incomplete saponification. These extra fats make the soap more moisturizing. This is also what makes modern hand made soap better than "Grandma's Lye Soap", the soap that folks remember "taking the hide off of ya". Grandma did not have the means to get pure lye. She had to make her own from potash and often there was more lye than fats in her soap. Which made the soap very harsh on the skin, but great for cleaning. Today, handmade soap is almost always superfatted and much gentler on the skin. This is also why bars labeled as laundry soap should never be used on the skin.
Syndet- The term stands for synthetic detergent. This is what you currently purchase at the grocery store. Most of those bars are not really soap but rather, synthetic detergents. These are often labeled as "moisturizing bars", "beauty bars", or "body bars". Check the ingredients on these items if you are trying to avoid SLS, a common irritant in high foaming detergent type products like bubble bath. Many solid shampoo bars are actually syndet bars.