Finally, a way to save your botched batches!
Whether the colour was poorly dispersed, the scent too weak, or the design off centre, your less-than-perfect soaps can now be given a second lease on life! You can also save failed attempts that ended up being too drying because you miscalculated the amount of sodium hydroxide or forgot to add oil (for example: forgot to add superfatting at trace!). You can also use this technique to recycle leftover soap bits.
Rebatched soap has a rustic, grainy appearance – it’s not as smooth as regular soap. One advantage of this technique is that the added essential oils and aromatic essences hold better in the soap since it has already been cured. Another advantage is that it allows you to recycle soap rather than just toss it out. Once remelted and remolded, the soaps can be used the very next day (or in just a few days) Hurray!
Before you start
- If you’re trying to save a caustic soap, we can’t guarantee that your rebatch will be safe to use. It all depends on the original mistake. If there are sodium hydroxide granules in the botched batch, they may not melt in the crock pot. In case of doubt, throw this soap away. But if the sodium hydroxide is evenly distributed, soap that is a bit drying can be remelted: you just need to add the missing oil to restore the right moisturizing level. We carried out some tests with caustic soaps that had been poorly mixed (cauliflower patterns could be seen on the surface, revealing the dried sodium hydroxide). Keep reading to find out if we were able to save them!
- The rebatching must be done after the soap is cured since that’s when you can conduct tests: is it caustic and drying to the skin? Did the fragrance hold well?
- Add a little vitamin E to your oils to prevent them from turning rancid. It would be a shame to remelt your soap, only to have it turn rancid a few months later.
- A cleaning tip: if your crock pot or food processor become coated with soap, just soak them in hot water to melt the soap, then rinse. They’ve probably never been so clean!
- Botched batches or cured scraps
- Demineralized water: calculate 15 to 30 ml per 100 g of botched soap
- Melted vegetable oil or butter of your choice (superfatting): 3 g per 100 g of soap
- Essential oil or aromatic essences of your choice: 3 g per 100 g of soap
- Vitamin E: 1 g per 500 g of soap
- Food processor (ideally – if not, a manual grater)
- Crock pot
- Ramekin to measure oils and essential oils
- Measuring cup
Steps to follow
*see recipes in the next section*
1. If the soap is caustic, wear gloves.
2. Grate the soap. A food processor will do this very quickly, but – if you have the patience – a manual grater will also work.
3. Weigh the soap to be remelted.
4. Place soap in crock pot at the lowest possible temperature (heat, keep warm, or low).
5. For every 100 g of soap, add 1 tablespoon (15 ml) demineralized water if your soap is fairly soft (if you can shape it with your fingers) or two tablespoons (30 ml) demineralized water if your soap is fairly hard (breakable). It’s better to start with less, and add more later, than to add too much, and end up with mushy soap. Stir with the spatula.
6. If your soap is caustic, add the vegetable oil (3%) now so the oil and sodium hydroxide will saponify as it melts.
7. Cover and warm the soap in the crock pot for about 2 hours, stirring once or twice. Resist the temptation to lift the cover and stir too often! If you stir too much, you’ll add air to the paste, and the melted soap will be lighter.
8. If the soap seems to be sticking or burning, add a little water. The soap should become translucent in places over time. It should have the consistency of a paste.
9. Add the superfatting, essential oils, or aromatic essences and mix well with the spatula.
10. Pour into molds using a spoon, pressing the mixture between layers as necessary.
11. Unmold after 24 hours or longer if the soap seems too soft (there’s no need to cover the soap during this period).
12. Slice if necessary and use immediately or let dry and harden for a few days. If you used a caustic soap, you will have to wait a few weeks to give the sodium hydroxide time to completely saponify.
Our rebatching recipes
We began with 1 kg of various shades of pink soap, unscented. We grated it all and divided it into two piles to carry out two tests.
We also had 2 kg of caustic blue soap. When it was first made, the sodium hydroxide was not hot enough, so it cooled the oil mixture and caused it to partly solidify. The resulting soap had small pockets of sodium hydroxide, some of which rose to the surface, where you could see the dried product. See tests 3 and 4 to find out if we were able to salvage these caustic soaps!
Test No. 1: non-caustic, colored, and unscented soap
|Characteristics of the botched soap||Additions|
Verdict: the soap poured into individual molds was easily unmolded the next day and used the same week. The scent was pleasant and remained in the soap for a long time. The soap was enjoyable to use!
Test No. 2: non-caustic, coloured, and unscented soap
*Scenting and colouring*
|Characteristics of the botched soap||Additions|
Verdict: The colorant dispersed throughout most of the melted paste, but some of the larger soap chips did not melt, so they were visible in the soap. It was pretty and smelled good!
Test No. 3: Caustic, coloured and unscented soap
*Scenting and addition of oil at the beginning*