using master batched lye

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Well-Known Member
Feb 13, 2015
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my apologies to you all for yet another lye question but I'm having a mental block or something on this issue...while totally able to wrap my brain around the time saved in this technique and the advantage of not having all that excess water to evaporate out of a bar of soap...
so lets say I make a 50% lye solution...equal parts by weight lye and water.
I'm going to make in theory a 33% total lye solution for a specific batch of soap using aloe vera liquid or milks to bring me to that concentration of solution in the soap batter...i.e. add the additional liquids to the batter after adding the lye solution of 50%...
Here's the I simply plug in to soap calc to get that additional liquid measurement...just so you know...I've been working with the 38% default all my soaping career...I've never fiddled with that column on soap calc.and part of me would like to know the math involved of bringing a 50% solution to something in the 30's% range...
I've heard it mentioned that this is kindergarten math ...maybe I was absent that day...:confused:
Nov 19, 2013
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However you calculate your water amount in what ever calculator, you end up with a lye amount and a water amount. For this example -

150g lye and 350g water

So I have my 50% lye solution, so I know that 300g of it contains 150g lye and 150g water. I put that 300g of my solution in a pot.

So I have my right amount of lye, but only 150g of my required water amount. I then just add in to the pot enough water to get me to my water goal - in this case, 200g more water.

That is the same process regardless of which water option you choose in the calc.


Professional Geek
May 20, 2015
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Kingston, Georgia, USA
If you have a 50% lye solution ie 1:1 and you want a 33% solution ie 1:2, you take half the amount of the fifty percent solution as your weight and add that much more water, if you want a 25% solution ie 1:3 you add the entire solutions weight in water/whatever liquid