# lye concentration

Discussion in 'Lye-Based Soap Forum' started by ToniD, Nov 17, 2010.

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1. Nov 17, 2010

### ToniD

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I have read that choosing a lye concentration is a better method of soaping than do liquid as a % of oils, and that the lye concentration is important in the outcome of the soap.

How do I intelligently choose a correct concentration for a particular recipe?

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2. Nov 17, 2010

### IrishLass

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I like using the lye concentration box instead of the liquid as % of oils box. It just makes more sense to me.

I use a 33% lye concentration most of the time, which calls for less water than a 'full-water' amount (i.e. 25 % to 27% lye concentration), but not so little water as to encourage potential problems for the majority of my batches. I've found it to be a safe, middle of the road concentration, even for beginner soapers. It plays well with the majority of my formulas and allows me to unmold my soaps within 6 to 12 hours (depending on my oils), and also allows my soaps to harden up much faster and to cure without warping.

If I'm using an ornery FO that doesn't necessarily seize, but moves fast at 33%, I'll kick my concentration down to 30% or 31%.

If my FO is a seizer, I'll use full water (27%) and HP it.

If I'm doing a 100% olive oil Castile with a very well behaving FO, I'll soap with a 48% lye concentration.

Here is a little chart for your notes:

25% lye concentration is 3 times water as per lye
33% lye concentration is 2 times water as per lye
And 40% lye concentration is 1.5 times water as per lye

Solution Strength chart
Lye x 1.0 = 50% (I would never go this far, its the physical limit)
Lye x 1.15= 46.5%
Lye x 1.2 = 45.45%
Lye x 1.25= 44.44%
Lye x 1.3 = 43%
Lye x 1.4 = 41.66%
Lye x 1.5 = 40%
Lye x 1.6 = 38%
Lye x 1.7 = 37%
Lye x 1.75= 36%
Lye x 1.8 = 35.7%
Lye x 1.9 = 34.5%
Lye x 2 = 33%
Lye x 2.1 = 32%
Lye x 2.3 = 30%
Lye x 2.7 = 27%
Lye x 3.1 = 25%

HTH!
IrishLass

3. Nov 18, 2010

### Hazel

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ToniD - Thanks for asking the question.

IrishLass - Thanks for answering.

4. Nov 18, 2010

### ToniD

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Thank you so much for that comprehensive helpful answer, Irish Lass!

5. Nov 22, 2015

### magdiel1975

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Hi..
Not understanding your math here.. Lye x 2 does not equal to 33% water solution. I am wondering how are you coming up with this math.. please explain.

6. Nov 22, 2015

### notapantsday

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The amount of water you need is 2 x the amount of lye. So say you have 100g of lye, then you need 2 x 100g of water.

100g lye + 200g water = 300g solution

100g lye / 300g solution = 33%

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7. Nov 22, 2015

### magdiel1975

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Well Im confused now because all the lye calculators I have used..brambleberry, SoapCal and a few others tells something different..

Let's say Im using a 47 oz total oils recipe... according to SoapCalc 33% is 6.69 oz of Lye and 15.51 oz of water, which is not 6.69(lye) x 2.

SoapCalc says that for 33% I need 6.69 oz of lye and 15.51 oz of water which is not even close to 13.38 oz. (lye x 2)

I would have to select 28.5% in order to get ~6.69 oz. x 2 = 13.38 oz.
Now you see what Im confused?

8. Nov 22, 2015

### Muskette

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magdiel1975, you want to use the "Lye Concentration" setting, not the "Water as % of oils" setting.

9. Nov 22, 2015

### IrishLass

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Ditto^^^^.

Magdiel- there are 2 completely different ways to calculate water on SoapCalc (which will give you 2 completely different results from each other). One way is by using their 'Water as % of Oils' box, and the other way is by using their 'Lye Concentration' box (in which the water is based on the lye amount, as opposed the oils amount).

Here is a thread that will help to explain the difference between the 2 different ways, and also why it's best to calculate your water amount based on the lye instead of on the oils:

IrishLass

Last edited: Nov 22, 2015
10. Dec 21, 2016

### macster2075

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I too have been wondering about this Lye Concentration of 33%.
I read the info on that link provided above, but I am still a bit confused.

In SoapCalc I have 44oz of oils at 33% Lye Concentration.
It says to use 6.14oz of lye and 12.48oz of water.

I am not understanding how lye x 2 equals that water amount..
using the previous formula above of
"100g lye + 200g water = 300g solution"

So 2 times the amount of lye translates to 6.14 x 2 = 12.28, right?
so 6.14 + 12.28 = 18.42oz of water - - am I completely lost here or what?

According to that math, I am supposed to be using 18.42oz water, but SoapCalc says to use 12.48oz.

11. Dec 21, 2016

### magdiel1975

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ha..
Yeah, that math got me confused as well and personally, I don't think is right... just multiply your lye of 6.14 times (67/33= 2.03).. so in your case, lye is 6.14 x 2.03 (NOT 2) = 12.46oz of water.

so yeah.. it's not that 33% lye equals to lye times 2... it's more like Lye times 2.03, which was the part that confused me as the math did not add up..until i found that it was actually 2.03.

12. Dec 21, 2016

### The Efficacious Gentleman

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That's because smaller parts of a larger whole and you have to be careful:

Taking 10% away from 100 gives you 90, but adding 10% on to 90 does not give you 100.

In the case of 33% concentration, it's made harder by the rounding factor. One third of 100 is not 33. If you multiple 33 by 3 you only get 99. A third of 100 is 33.3 with the .3 recurring with no end (33.3 x 3 isn't 100. 33.33 x 3 isn't 100 and so on) so some fudging will be required.

13. Dec 21, 2016

### magdiel1975

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Yeah..
i ended up soaping at 30% lye Concentration to match my molds..
since i would multiply the LxWxH, then x .41 to get the size of the mold..
but i have noticed that to get the right amount of water to fill the molds, I use 30% Lye concentration or 33% water percentage (which both are very similar amounts of water) to exactly fill my soap molds.. it's been working great.

14. Dec 21, 2016

### kchaystack

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a 33% lye concentration is 1 part NaOH to 2 parts water. So soap calc is right.

after you mix your lye and water together you would have 18.42 oz of solution, but you only use 12.28 oz of water.

If you use 18.42 oz of water, then you will have a 25% lye concentration, or 1 part NaOH and 3 parts water.

15. Dec 21, 2016

### DeeAnna

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If you want a lye concentration of 33%, then you got exactly what you asked for. We're being a little sloppy with the numbers. A ratio of 2 parts water to 1 part NaOH (2:1 water:lye ratio) is not 33% concentration, even though many of us say it is (even me). It's actually 33.33333333...% concentration (or 33 1/3% to use a mixed fraction).

So "...In SoapCalc I have 44oz of oils at 33% Lye Concentration. It says to use 6.14oz of lye and 12.48oz of water...."

Those numbers are correct as stated. The math to calculate lye concentration from the weights is this:
Lye concentration = NaOH wt / (NaOH wt + water wt) X 100 = 6.14 / (6.14 + 12.48 ) X 100 = 32.975...% which rounds nicely to 33%.

Given the NaOH weight and desired concentration, this math relationship can be turned around to get the water weight instead:
Water wt = (NaOH wt / Lye concentration X 100) - NaOH wt = (6.14 / 33 X 100) - 6.14 = 12.46606 which rounds to 12.47.

The difference between 12.48 and 12.47 is due to the fact that I'm working with rounded numbers in this example and soapcalc does not round it's numbers when calculating.

Now if you want the water weight based on 33.33333333...% concentration, then use 33.33333333...% in the equations above, not 33%. Or shift over to a water:lye ratio of 2:1 which is the same thing.

Last edited: Dec 22, 2016
16. Jul 14, 2019

### Tonie

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Hi WallyN. the tips I have learnt along the way are to cut out butters, including cocoa and although I like coconut oil, don't use it unless it's fractioned and unless you want a quick trace. The rate of trace you prefer depends on the soap you are designing. And the rate of trace depends on the oils you are using. Slow trace - olive. No Rice Bran or castor oil or butters. I will only use castor oil in coconut oil based soaps for a bubbly creamy bar that sustains it's fragrance. Also try increasing your water content slightly. Once you've found your perfect trace, stick with it. Don't bother swapping and changing oils around because at the end of the day, oils is oils. Work with the oil that achieves best rate of trace for your needs and if you find that it traces too quickly, increase your water. Sunflower oil slows down trace as well. I have never used Palm oil so can't comment on it. Some people say that the fragrance they use affects the rate of trace. But for me I have not noticed a difference with my fragrances when I use olive oil and sunflower oil. It's all trial and error unfortunately and what works for some does not necessarily work for anyone else. But to make a difference, cut out the cocoa butter and increase your water and see how that goes. Also do not add hot lye solution to cold oil. Add room temperature lye to room temperature oil....try that too. Don't use stick blender, use whisk. Unless of course it's not emulsifying. Then use a few bursts of stick blend but no need to overdo it. Achieving trace is over rated. As for your lye content being too high, I can't comment on that since lye content needs to be an exacting percentage based on HLB of your oils and for that reason a lye calculator is handy. So if you think lye is the issue, just increase the water content rather than decrease the lye since you can't decrease your oils.

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17. Jul 14, 2019

### Relle

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Tonie, there is no WallyN on this thread. You must have meant to post elsewhere. Last time someone posted here it was 2016. You might be best to send this info by a pm, so he gets it.

18. Jul 14, 2019

### linne1gi

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I like using a ratio. It seems to work well for me. The default in Soap Calc is about 3:1. 3 parts water to lye. I prefer 2:1 to give me time to swirl. Or 1.7:1 in a plain bar.

19. Jul 14, 2019

### DeeAnna

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The default in SoapCalc is 38% water as % of oils. That's not mathematically the same as a water:lye ratio of 3:1. Using "38% water as % of oils", the water:lye ratio would just happen to be 3:1 (25% lye concentration) only if your recipe was something like a 100% olive oil or equivalent.

If you click on "lye concentration" or "water:lye ratio", the boxes are blank -- there is no suggested default setting in Soapcalc for these settings.

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20. Jul 14, 2019

### linne1gi

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I know DeeAnna - that's why I said "about" 3:1. Usually new soapers can't understand the concept of "water as a percent of oils" or even "lye concentration". But ratios make sense to a lot of people. That's why I used those words. Forgive me - this is not a snarky reply - just an explanation of why I said that.

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