Cold-process soap is a beautiful looking handmade soap that, when scented with essential oils and colored with botanical elements, makes for a project you can make at home that looks like it came from an artist’s gallery. Cold-process soap has no additives that are bad for the earth and it is gentle on sensitive skin.
There are many methods to making handmade soap such as cold process, hot process, milk soap, and rebatching. You can also make melt and pour soap at home very easily and skip the lye, as well as the weighing and mixing of the ingredients. I have made soap all of these ways, and each produces a very different type of soap. I like the hot process method for making beer, wine, and tea soaps.
I like cold-process soap most as my everyday soap. I usually make soap in big batches every year so I have plenty to choose from throughout the year and plenty more to give away.
Cold-process soap makes a wonderful gift for yourself and others, but it does require following the instructions to the letter. If you are a first-time soap maker, partner with a friend and make soap together – it helps to have a buddy system and it’s a lot of fun!
If you are not using a kit, the first and most crucial step in cold-process soap making is to weigh the raw ingredients (fats, lye, water) precisely. Prep everything that you will need and lay it out accessibly before you begin. Soapmaking measurements are done in weight, not volume, so be sure to get a good kitchen scale and weigh out the ingredients.
It’s best to wear protection when making soap as lye can burn your skin. Until the oils and lye have turned into soap (48 hours after making the recipe) it’s best to protect yourself. Always wear rubber gloves, safety goggles, and keep your work area free from kids and pets.
OILS: Gently (slowly) heat oils in a stainless steel pot on the stove. Alternatively, use a microwave and heat for two minutes on high, and then at shorter intervals until you reach the temperature listed in the recipe.
LYE: Using room-temperature distilled water, weigh the amount specified by the formula into a heat-resistant glass bowl or large Pyrex measuring cup. While stirring, slowly add the measured amount of lye. I repeat, SLOWLY. It’s important to note that you add the lye to the water, not the water to the lye. Stir until dissolved. This mixture will get super hot quickly so be mindful of that. Also, the fumes are terrible, so if you can stir from below the fumes (with lye on the counter and you crouching below as you stir) outdoors or at least with windows open, that would be best. Place glass container in an ice-water bath and cool to required temperature. Get accurate temperature readings with a candy thermometer in the middle of the solution.
When both oils and lye/water are at the required temperatures (as stated in your recipe), slowly pour lye/water into the oils while rapidly stirring in small circles. Always add lye/water to oil, not the other way around.
Continue to rapidly stir the mixture until it thickens to the consistency of pudding (called “tracing”). The mixture is ready to be molded when a drizzle mark from the spatula remains for a few seconds on the top of the mixture. Speed up the tracing process by using a hand blender to mix. Be careful not to over mix.
Add essential oils, natural colorants, and herbs or exfoliants at this stage (see recipes below). Work fast as the mixture will quickly start to thicken. There are many options for coloring and scenting soap but I avoid perfumes, fragrance, and artificial colors. I like handmade natural soap scented with pure essential oils and colored with natural dyes. As you can see by these three recipes, it looks beautiful and it smells even better!
Pour mixture into 1L milk cartons and staple the tops shut. Wrap the cartons in a large towel and set somewhere warm for 48 hours like the top of the fridge. The cartons will feel warm and will get hot as the mixture neutralizes and turns into soap.
To unmold your soap, peel off the milk cartons and cut each full 1-liter carton lengthwise into 3 equal sections for shower soap, and 4 equal sections for hand soap. Flip each section so that it appears to be a square from the top, and cut into 3 equal sections.Place each bar on a wire rack in a cool, dark place to cure for three weeks. After three weeks, soap can be buffed with a cotton cloth and wrapped for gifts.