# Trying to understood Lye water master batching

Discussion in 'Beginners Soap Making Forum' started by Cal43, Mar 1, 2019.

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1. Apr 25, 2019

### IrishLass

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Hi Steven- what The Efficacious Gentleman wrote in his post does not make sense to me either. The correct amount to add to the OP's recipe is indeed 6.15 oz, not the 4.41 oz The Efficacious Gentleman's post seems to be saying. I'm not sure why he said that.

IrishLass

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2. Apr 25, 2019

### LilianNoir

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No, that's not quite it. The amount of water added is however much the original amount calls for MINUS half of the amount of 1:1 solution added. Because half of that solution is lye and half is water.

So, as another example.

I had a recipe that called for 8.0 oz water, 4.2 oz lye.

To use my 1:1 lye solution(so half lye, half water), I take a look at the amount of lye required and double it: 4.2x2 = 8.4. So I know that I need to measure out 8.4oz of lye solution in order to meet 4.2oz lye.

With 8.4oz of solution, just as there is half (4.2oz) of lye, so there is water.

I know that my 8.4oz of solution gives me 4.2 oz of water. So to determine how much more water to add, I take the original amount called for: 8.0 oz and subtract the amount of water i know is present in my solution - 4.2

8.0-4.2= 3.8. I need to add 3.8oz to meet the water requirement of 8.0 oz.

So to summarize: I double the amount of lye required to know how much solution to use. 8.4oz of 1:1 lye solution. Then subtract the original amount of lye called for(or, half the amount of solution) from the original water requirement to determine how much extra water/liquid.
8.4oz of solution, and 3.8 oz of water.

You can also check your math by adding together the originally called for amounts of lye and water (8.0 + 4.2 = 12.2) and then add together your calculated amounts of lye solution and additional water (8.4 +3.8=12.2)

Does that help at all (or did i make it worse? )

I think I see the problem.

@The Efficacious Gentleman wrote
Which I think is being misinterpreted as "Required water EQUALS half of the 50/50 amount", but what is written and meant is "Required(by the recipe) water MINUS half of the 50/50 solution amount." to get the amount of added water.

Last edited by a moderator: Apr 26, 2019
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3. Apr 25, 2019

### IrishLass

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You hit it right on the nose, LilianNoir. I completely misinterpreted what Effy said.

@Steven - ditto what Lilian Noir said.

IrishLass

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4. Apr 25, 2019

### Steven

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@LilianNoir your explanation is in line with the math I was doing. Thank you for the clear step by step outline! I see your second post and I think that helps. It still took me a minute, but I think I got it after a couple reads.

@IrishLass thanks!

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5. Apr 25, 2019

### LilianNoir

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You're very welcome! I used to teach math, so I hoped those skills were still around!

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6. Apr 26, 2019

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When using the dual-lye, how you do the calculation when you master batch the lye?

7. Apr 26, 2019

### earlene

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When I do dual lye soaps, since I only masterbatch the NaOH, I just use the extra water to mix with the KOH.

Most of my dual lye batches are 95% NaOH and 5% KOH, so the extra water needed to make up the difference of water needed for the recipe is usually sufficient for mixing the KOH.

Example:

Say my Recipe calls for the following:

137.1 grams water
62.4 grams NaOH
5.1 grams KOH

137.1 + 62.4 = 199.5 (total water plus NaOH)

199.5 - (62.4 x 2 = 124.8) = 74.7 (The 62.4 x 2 is to calculate how much of my MB lye I need.)

or 137.1 - 62.4 = 74.7 (This is to double check my math, a step I left out when I originally posted the calculations.

This means I need 74.7 grams additional water, which I use to mix with my 5.1 grams of KOH.

The above example is based on a [33% Lye] Concentration.

Edited to correct my math, which was off. SO sorry for my errors - I must have been too tired for math!

Last edited: Apr 26, 2019
8. Apr 26, 2019

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Thank you earlene.
How do you calculate the chelator? I would like to know how to do it with both citric acid and EDTA, if possible.

9. Apr 26, 2019

### earlene

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I use a combination of EDTA with ROE since together they help prevent DOS, and the EDTA reduces soap scum exceptionally well. The calculations are fairly easy with EDTA. DeeAnna has put together instructional material on the use of EDTA at her site, classicbells. Here is the link for EDTA: https://classicbells.com/soap/EDTA.html

Because I have plenty of EDTA, I have had no need to use citric acid as a chelator, but the calculations can be found here.

10. Apr 26, 2019

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When do you add EDTA and how to calculate with the master batch of lye?
I am not as fluent in calculating EDTA, but still like to master using it. I have some of my friends and family members still prefer citric acid over EDTA, I do well with citric acid. My question is when to add citric acid in lye master batch?

11. Apr 26, 2019

### earlene

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Personally, I wouldn't add the chelator to the masterbatch lye, particularly if some of your soap is going to be made with one chelator, while other soap is made with another chelator. I prefer to keep the lye as purely lye until it is time to use it in soap. With any added material in the masterbatch lye solution, it would alter the measurements when you go to weigh out the amount needed for each batch of soap.

I masterbatch my lye and only use as much as I need for each soap I am making. Normally I don't add anything to the lye before mixing it into the soap unless I want to melt some silk into it.

I masterbatch my 50% EDTA solution and keep it in a plastic bottle, then add the amount needed to each batch. I don't actually add it to the lye at all. Usually I add it with the oils or with the fragrance.

I use 0.5% EDTA in my soap, so for a total batch size of 500 grams, that is 2.5 grams of my 50% EDTA solution. The calculations are really made pretty easy when using the 50% solution.

12. Apr 26, 2019

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Thank you earlene.

13. Apr 26, 2019

### atiz

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I have been following this thread because found it interesting. But I'm not sure I understand the example. If you need 62.4 g NaOH, isn't it the case that your [50%] master batch lye will have 62.4 g NaOH + 62.4g water in it? If so, the additional water needed is not 12.3 but (137.1 - 62.4) = 74.7 g.

I think I understand the rest.

14. Apr 26, 2019

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I think you made a mistake with the last part, the 12.3 is the final amount of water needed for a batch of 33% lye solution.
(62.4 x 2 = 124.8) is for an equal amount of lye and water.

15. Apr 26, 2019

### atiz

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Equal amount of lye and water = 62.4 lye + 62.4 water.
According to Earlene's example recipe, you need 137.1 g water total. So with your "equal amount of lye and water" (from the masterbatch) you have taken care of 62.4 g water out of this 137.1 g. Which means you still have to add 74.7 g.
At least this is how I would calculate it.

16. Apr 26, 2019

### earlene

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Yes, you are correct, I guess I was too tired for math last night. I will adjust my above post to correct it! Thank you so much for pointing that out!

17. Apr 26, 2019

### earlene

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No, atiz was correct. My math was off, either because I was too tired to check my own work, or just too tired. Anyway, I have corrected my original post to reflect the proper math. And the double checking method I normally use to check my math. So I hope you haven't yet made any soap with the wrong calculations!

Last edited: Apr 27, 2019
18. Apr 26, 2019

### atiz

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Oh okay, thanks -- and sorry, it wasn't meant as a correction really, I just wanted to make sure I understand this masterbatch thing (since I don't make that much soap I don't actually masterbatch, although have done the "split method" when adding other additives to water).

19. Apr 26, 2019

### earlene

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Oh, no problem whatsoever, atiz. I certainly don't want any mistakes I make to sit here on the site uncorrected! That would be horribly embarrassing, as well as possibly creating future confusion. So I am truly grateful it was caught and I was able to edit the post to fix the original post with the error. We are all fallible, after all, right?

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20. Apr 26, 2019

### Susie

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DW, I know I am late to the party, but no one has responded to you on whether you can "feed your masterbatch" or not. I don't, just because it can continue to absorb moisture inside the plastic jug. Mine, unless I store them in the Super Dry Storage Buckets (SDSB) with the Damp Rid and the Gamma Lid, routinely increase in weight between uses. And I live in DFW with a much lower relative humidity than the Jackson metro area. So I know yours is sucking up moisture also. Hence the SDSB. I have old NaOH 32 oz containers from ED that I store my masterbatch in, and I wait until I am on the last one before making more.

I masterbatch my KOH/NaOH blend at the same time. Why not? You know how much you need per batch.

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