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Cold Process Method

Updated: Jul 1, 2023

Picture of the Salem House Provisions Lake Retreat soap.

Since so many new friends are interested in what is happening at the Soap Mill, I thought I would tell you about the type of soap I make. There are four different types of handmade soap: rebatch (or hand-milled), melt and pour, hot process, and cold process. I have made all of these at least once (except for the hot process), but I prefer the cold process over all the others. What is cold process soap, and why do I love it so much? Cold process soap is called cold process because no heat is used when making this soap. One aspect of this method that I like is that I have complete control over the types of oils and butters I want to use in a recipe. I like this because I can tailor a soap to a particular need, like dry or aging skin. I also can pick the type of liquid I want to dissolve my sodium hydroxide in, like coffee, tea, distilled water, or different types of milk. Your skin reaps so many wonderful benefits when using milk in the cold process method. Probably the part I get most excited about is the design aspect. The possibilities are limitless regarding the many different designs one can achieve with the cold process method.

Picture of a loaf of soap from Salem House Provisions.

So, I have told you what the cold process method is, but how do oil and liquid actually make soap? It is through a fancy word called saponification. Saponification is the reaction between the sodium hydroxide (lye) and oils that cause the oil molecules to bind together and form soap. The liquid that the lye is dissolved into is what facilitates this change. So, after researching and learning what each oil or butter brings to the table regarding vitamins and moisture for your skin, I learned they also all perform differently in the soap. Some oils or butters give a creamy lather, some give big bubbles, and others give small to none. I use all this information when formulating a recipe to bring you the best bar possible for your needs. I can then boost the bar's performance by adding milk as my liquid. I take all this information and put it into a soap calculator to ensure I am using the proper amount of lye for the oils and butters I am using. A lye-heavy soap will be harsh on your skin, and one that doesn't have enough lye will be soft and mushy and probably will not cure. Everything has to be measured out precisely before mixing. Then the proper temperature has to be reached before adding the lye mixture to the oils and butters. Once they are added together, you blend them until emulsified. Then the fun starts with the design process. After the soap is made and put in the mold, I usually leave it for 48 hours. Once I remove it and cut it into bars, it has to cure for 4-6 weeks. I may do a short video in the near future and post it on the website for those interested to see the process in action. Let me know if that is something you would like to see. Soapmaking is a fun hobby. It can be dangerous, though. Precautions should be taken when doing hot and cold process soaps since you are dealing with lye, which can harm the skin and eyes or cause respiratory issues if inhaled. Rebatch and melt and pour options are great if you do not want to worry about safety issues. Look for upcoming blogs with more detailed information on the ingredients and their benefits in my soaps.

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