Master Batching Lye


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Well-Known Member
Jan 13, 2014
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This might be a silly question but I've never mater batched lye before. I've been reading where soapers are master batching lye for future use at room temperature. Does that mean their lye/water concentration will be the same for every batch of soap that is made? Does that eliminate allowances for superfatting.


Lifetime Supporter
Dec 25, 2012
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No, you can create any final lye concentration that you want as long as you know the concentration of the masterbatch solution that you start with.

The easiest way is to make/start with a 1:1 masterbatch solution. Then you just need to add twice as much of that solution as the amount of lye called for in the recipe (because only half of that solution will be lye; the other half will be water). After putting that in your oils, also add to your oils just enough extra water to make up the difference between how much water was in the masterbatch solution and how much water the recipe calls for.

As for getting the right superfat, it is no different regardless of whether you are using a masterbatched lye solution. You must always tell the lye calculator what superfat you want (and your oil composition), and it will tell you how much lye you need. Looping back to the paragraph above, use twice as much of 1:1 masterbatched lye solution as that amount of lye called for in recipe to ensure your desired superfat.

One thing to clarify about the link to Susie's thread above: she was asking about masterbatching a lye solution that includes both sodium hydroxide (NaOH) and potassium hydroxide (KOH). KOH is not necessary in bar soap and I don't advise you use it unless you have a specific purpose for it and are an advanced soaper. Just stick with NaOH like most people do.


Staff member
Feb 11, 2008
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Right here, silly!
I master-batch my lye solution all the time @ a 50% or 1:1 concentration (i.e., 1 part lye to 1 part water).

As Krista said- no- you will definitely not be stuck having to make soap with the same lye concentration for each batch. And it does not eliminate your allowances for superfat either. If it did, I would never master-batch my lye. One of the beauties of making a 1:1 master-batch solution is that it's super easy to adjust it to whatever recipe you want to make @ whatever water amount/lye concentration % or superfat % you wish to use.

Here's another, albeit older, thread that may also be of help:

IrishLass :)