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Soapmaking Methods - Cold process, hot process, melt and pour

Updated: Nov 20, 2023

Cold process, hot process, or melt and pour... They all make soap. But what are the pros and cons of each method?


Did you know that there are several different methods to making soap? In this blog post I will briefly go over three methods of soapmaking providing a basic overview of the steps, cure time, benefits and downsides.

What is soap?

Soap is defined as 'a substance used with water for washing and cleaning, made of a compound of natural oils or fats with sodium hydroxide...' There is no soap without lye, period. Many commercial 'soaps' are not true soap as they are made with detergents instead of oils and lye. Thus they are labeled as beauty bars or such. Soap is made by combining oils and fats, such as coconut oil or lard, with lye. The combination of heated oils and lye produces a reaction called saponification, turning the liquids into a solid. After saponification is complete there is no lye leftover in the finished product.

Cold Process Soapmaking

With cold process soapmaking, you first measure your oils and fats out and melt them down together. You must also measure and mix your lye with your lquid, usually water or milk. The lye mixture is combined into the oils when both have reached about 100 degrees. You then mix them until the batter reaches trace, at which point you can mix in additicves such as herbs, essential oils, or coffee grounds. The soap is then poured into molds and after 24-48 hours it is unmolded and cut. During this time the heat from the process will saponify the soap loaves. The cure time for cold process soaps is four to six weeks.

Cold process soaps require a longer cure time than other methods but this produces a harder and longer lasting bar of soap. The batter is thicker than melt and pour but more fluid than hot process. This method provides a good base for additives that keeps them suspended throughout the soap rather than everything rising to the top.

Hot Process Soapmaking

Hot process soapmaking is very similiar to cold process. You will begin the same way- by measuring out all of your ingredients, melting and mixing, combining, and bringing the batter to trace. However, instead of pouring the fluid batter, with the hot process method you will continue to 'cook' the soap to speed up saponification. This is usually done in a crockpot. When the soap is done it will have a consistency much like mashed potatoes and will need to be spooned into the molds.

Because of the thicker batter, this method is usually not ideal for pouring into detailed molds or making fancy swirl patterns. Hot process method often results in a more rustic look and texture to the finished soap. It is technically ready to use once it has been unmolded since the soap was forced through saponification already. However, even hot process soaps benefit from a cure time to harden the bars more which allows them to last longer. If you need your soap ready faster, hot process is a good method to use.

Melt and Pour Soap

Melt and pour is a hot topic among soapmakers - some despise it and some swear by it. Regardless, the method is here to stay. If you don't know, melt and pour is exactly what it says- you melt a premade block of soap, add your colors and fragrance, and pour it into your molds. Melt and pour starts out just like cold process soap. It then has extra ingredients added to create the meltable base. Look carefully at the ingredients list of these bases, especially if you market natural soaps. The batter is usually very thin and additives such as herbs tend to float to the top rather than be evenly dispersed. The soap often has a shiny finish and due to the high glycerin content it will sweat in humid weather, something to take note of if you attend craft events outdoors. Soaps made with melt and pour do not last as long in the shower as traditionally crafted soaps. That said... melt and pour is ideal for extremely detailed molds, such as those for decorative soaps. It is ready to use immediately after unmolding and requires no cure time. For a kids craft it is a great choice as there is no lye to mess with and it is very easy to customize.

Now what?

Both the hot and cold process methods are more time consuming but they produce excellent quality soap bars from scratch. You have full control over the ingredients and can create truly all natural soaps. Fragrances, and additives are limitless. You can do many beautiful designs and embeds in traditional soap. You do have to work with lye, carefully measure and mix your ingredients, pay close attention to trace, and wait for soap to cure. Melt and pour bases give you less control over the ingredients. I personally do not use bases and would not label them as natural soaps. However this would be my go-to for a quick and safe kids soapmaking craft. This would also be ideal for people who make extremely detailed decorative soaps with many layers and colors. The bases mean you are not working with lye and the soap is ready to use immediately. Regardless of which method you choose... happy soaping!

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