How to Rebatch Soap?

How to rebatch soap

November 22, 2022

Rebatching soap is when you grate cold process soap and melt it back down with a little water in a slow cooker before remoulding it.

To rebatch cold process soap you will need:

  1. A slow cooker
  2. A grater
  3. pH strips
  4. Water

Why Rebatch Soap?

There are a number of reasons why you might want to rebatch soap:

  1. To rescue a batch of soap that has gone wrong. It may have riced or be lye heavy/light. Take a look at our cold process soap making troubleshooting blog post for more troubleshooting info!
  2. To add essential oils or colours after the soap has cured. There is a theory that the scent or colour will last longer in the soap if you do this.
  3. To make multiple colours and fragrances from one large batch of soap

How much Water to add to Rebatch Soap?

Start off with 15ml of water per 100g of soap. 

If you’re rebatching because your soap was lye heavy, test it with your pH strips. If the pH is still above 10, add another 15ml of oil and then test again. Keep adding oils until the pH is between 9 and 10.

If you’re rebatching because your soap was too soft and didn’t have enough lye, then you’ll need to add diluted lye solution until the pH is between 9 and 10. Use 10g of lye in 20ml of water and start adding it, testing regularly.


1. Cut your soap

Chopping soap for rebatching
  • Cut or grate your cold process soap. If it is freshly made or lye heavy then make sure you wear gloves.
  • Add your grated soap to the slow cooker. 
  • Add your water or oils (see the previous section for how much water, or if you need to add oils)

2. Melt your soap

Melting soap for rebatching
  • Melt your grated soap with your slow cooker on low, come back to it every 30 minutes or so and stir it. Add more liquid if required.
  • Melting the entire batch can take 2 or 3 hours so allow yourself plenty of time.
  • Once it is fully melted it will be thick and gloopy, you can add colours or fragrance at this stage and then scoop it into your mould.
Rebatched soap setting in a mould

Curing soap after rebatching

Allow for 4 - 6 weeks for curing. It could take less time to cure if you’re rebatching soap that has already fully cured but stick with 4-6 weeks to be sure.

How to Rebatch Soap in the Microwave?

We wouldn’t advise rebatching soap in the microwave, you have to use a heating method that applies low and consistent heat over a couple of hours.

Rebatching tips

Don’t dive in and add loads of water! Start small and keep adding if you need to.

Rebatching soap can be a really useful skill to add to your soap making repertoire and can be a great way to fix soap gone wrong!

However, the finished product will be more rustic than your original cold processed soap. It may end up with lumps you have missed or air bubbles but the end result will still be a lovely bar of handmade soap.

Rebatched soap

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