How to Rebatch Cold Process Soap

Rebatching is a great way to “recycle” cold process soap. If you have bars sitting on your shelf that the scent faded from or a scent/ appearance you don’t like, turn it into something new! Here are the steps to get new life from old soap.

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If you are a soap maker, you probably have some soap scraps left over or bars and loaves that didn’t quite turn out how you wanted. Don’t throw them out! It’s time to rebatch and recycle that old soap into something new!

I make cold process soap with raw goat’s milk, but you can rebatch any kind of cold process soap. There are different ways to rebatch soap, I am going to show to you an easy method to do it with a slow cooker. This process takes me between 2 and 3 hours, so plan accordingly.

Rebatched vs. Regular Cold Process Soap

Rebatched soap is described as more rustic in appearance. It is difficult to make it very smooth or do any kind of swirling patterns, but it is still good soap.

One nice thing about rebatched soap is that it is ready to use sooner than regular cold process soap (which requires a 4-6 week cure time). Rebatched soap isn’t undergoing a chemical change after pouring, saponification already happened when it was first made, allowing 2 weeks for the added water to evaporate will leave you with a solid, long-lasting recycled bar.

Materials Needed for Rebatching Cold Process Soap

Soap scraps
Kitchen scale
Soap mold
Slow cooker
Cheese grater
Spatula
Mica powder or other colorant (optional)
Fragrance (essential oil or fragrance oil)
Distilled water
Soap cutter

I weigh out my soap scraps before I start so I know how much I need to grate down and fill my mold. I use large, rectangular, 2-pound silicone molds that nest inside pine insulating boxes, but any kind of mold will work.

I have a slow cooker that I use just for rendering tallow and lard and making soap. I recommend keeping soap making utensils and appliances separate from the ones that you use for preparing food for your family. The same goes for the cheese grater and spatula. I prefer to use a flat grater that I can lay right over the slow cooker, it’s less messy!

If you want to make the rebatched soap a different color and scent than the scraps that you are using you will need to add colorants and fragrance. You can use mica powder, clays, activated charcoal, or spices to color your soap. For fragrance you can use your favorite essential oil or a fragrance oil. If you are opting for fragrance oil, I recommend one from Brambleberry.com. Their products made especially for soap making and are skin-safe, phthalate and paraben free, and made from superior ingredients.

Distilled water is used to moisten the melted soap pieces and get the soap batter to a pourable consistency. I use distilled water so that I know there isn’t any bacteria or impurities that could impact my final product.

Once the rebatched soap has cooled and hardened, you will need something to cut it with. A box-type soap cutter, wire cutter, or a regular old kitchen knife works too.

Directions for Rebatching Cold Process Soap

1. With your kitchen scale, weigh out the soap scraps needed to fill the mold
2. With a cheese grater, grate as many soap scraps as will fill your slow cooker (you will have to add some later, not all of it will fit at once)

3. Add 1 ounce of distilled water to the grated soap
4. Put the slow cooker on low
5. Stir the water and grated soap with the rubber spatula
6. Once the grated soap begins to melt and condenses, grate more soap and add more water
7. Stir occasionally to keep the soap from burning and sticking to the sides of the slow cooker
8. Keep adding until all pre-weighed soap scraps and 4-6 ounces of distilled water have been incorporated into the slow cooker
9. Once the soap batter is a thick, but pourable consistency, add the desired amount of colorant and fragrance (I usually use 2 teaspoons each of colorant and fragrance)
10. Stir to combine
11. With your spatula, scoop the soap batter from the slow cooker and pack it firmly into the mold. You will want to pound the mold firmly on the counter several times to get rid of any air spaces.
12. Allow the soap to cool and harden in the mold for 24 hours. I leave it out, uncovered on a countertop