Water percentage

Discussion in 'Lye-Based Soap Forum' started by rjalex, Dec 8, 2013.

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  1. Dec 8, 2013 #1

    rjalex

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    In SoapCalc the only value I took for granted is the "Water as % of oils" which by default is set to 38%.

    What values to use, when, why ? For example a soft soap fatty acid formulation such as 100% OO could benefit from a lower value to get it cured sooner ?

    Thanks
     
  2. Dec 8, 2013 #2

    seven

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    I dont use percentage, i got confused by it. I rather use the 3rd option/bottom one, such as 2:1, 3:1...

    You were right, it depends on the oils. Also, the technique you're using (cp, hp, layers, etc), additives, fo/eo.

    With cp i usually go 2-2.5:1, while hp 3:1 always. I have never tried using less than 2, perhaps someday i will when i make a simple formulation.

    I think it's been said many times here, with hp, it is better not to do water discount, as some of the water got lost during the cooking process.

    I dont really care about curing time. I have come to accept that no matter what it is 4 weeks minimum for cp, longer for castile/high liquid oils. It's more for soaping convenience for me, for example no water discount for hp coz i dont want dry soap batter that is annoying to put into mold. Or, more water if i am using floral fragrances that are known to speed up trace.
     
  3. Dec 8, 2013 #3

    Obsidian

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    I generally use 33% anymore unless I'm making salt bars or a recipe I know traces fast, then I will use 38%.
     
  4. Dec 8, 2013 #4

    DeeAnna

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    Either use water:lye ratios as Seven does or use NaOH solution concentration in percent. Both are measuring what you really need to know -- the lye concentration. I don't know where the lye as % of oils comes from, but it's not particularly useful information, so I don't use it in my soap making.

    1:1 water:lye ratio is a 50% NaOH solution. Tricky to get the NaOH fully dissolved, so I do not recommend this for beginners.

    1.5:1 water:lye ratio is a 40% NaOH solution. This is a less common "lye discount".

    2:1 water:lye ratio is a 33% NaOH solution. This is probably the most common "lye discount". I normally use this solution concentration.

    2.5:1 water:lye ratio is a 28-29% NaOH solution Basically, this is "full water" and roughly translates to 38% NaOH as % of oils.

    3:1 water:lye ratio is a 25% NaOH solution. Some use a lye solution this dilute when making HP soap. If used for CP soap, this much water can prevent the soap batter from forming a stable emulsion, so the soap can separate out after being poured in the mold.

    More concentrated lye solutions (33% and higher) do NOT shorten the cure time, regardless of the "common wisdom" that says it does. It takes time for water to migrate from the center of the soap to the outside surface where it can actually evaporate. That process is slow, regardless of what lye concentration you used to make the soap. There are several informal studies from the last year or so that are floating around on SMF. They show the rate of weight loss from "full water" soaps and "water discount" soaps is about the same.

    A more concentrated lye solution does tend to reduce the time to trace, and that is helpful with a recipe that is mostly or all liquid oils. It also will tend to make a harder soap at the time of unmolding, again helpful with a recipe that is mostly or all liquid oils. Using a "water discount" is not any more dangerous or risky than using a "full water" lye concentration. I don't get this bit of "common wisdom" either. :)
     
    Last edited: Dec 8, 2013
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  5. Dec 9, 2013 #5

    new soaper

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    I'm pretty new at this and got stuck on this today w a recipe that I ran through soap calc. I love using it to know the hardness and conditioning and what not of my soap, and being new I couldn't figure out the lye/water form soap calc so easy, So I took my final recipe from soap calc and plugged it into mms lye calculator to get my Amt. And it helped confirm my recipe was consistant. However I am very new at this so I'm sure the pros out there have a quicker way.
     
  6. Dec 10, 2013 #6

    goteeguy

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    I used to use 28% NaOH solution, but have switched to 33% instead. It provides a faster trace for my oils and produces a firmer initial bar. (I also figure less water needing to evaporate out of the finished bars the better.) It doesn't really shorten the cure time though... I am tempted to try a batch with 40% NaOH solution, but I suspect the working time will be severely shortened.
     
  7. Dec 10, 2013 #7

    rjalex

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    OK so the default value in SoapCalc of Water as % of oils of 38% corresponds to a 26% of NaOH / water solution with my recipe. I feel it works quite well and feel safe about all NaOH dissolving. Might try 30% next time and see. Thanks.
     
  8. Dec 10, 2013 #8

    DeeAnna

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    "...OK so the default value in SoapCalc of Water as % of oils of 38% corresponds to a 26% of NaOH / water solution with my recipe...."

    Yep, that sound about right. Possibly your recipe has borderline too much water, especially for CP soap. If you're having any trouble with the soap separating after it's poured into the mold, I'd increase the NaOH solution concentration.

    What's really confusing about converting a recipe from "NaOH as % of oils" to "% NaOH in the water-NaOH solution" is that the saponification value has to be included in the translation. This means the NaOH solution concentration will vary from recipe to recipe depending on the different fats being used. Ugh. :problem:
     
  9. Dec 11, 2013 #9

    goteeguy

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    And that's what SoapCalc is for... :clap::thumbup::D
     
  10. Dec 11, 2013 #10

    yafa

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    My two cents:

    SoapCalc of Water as % of oils???

    The Percentage is used to express the amount of anything in the "whole thing" . In this case water is not part of the total, as it only calculates the amount of water divided by the total mass of oils ( only the oils). I can't think why they are using it, the only reason I can think of, is to give you an idea of how much water do you have compared to the weight of oil. I would rather prefer to know the percentage of NaOH in the soap mixture.

    For a 75% OO and 25% CO soap recipe( all amounts are in ounces):
    initial lye percentage in soap = 2.241/ (2.2411+6.08 + 16) = 2.241 / 24.321 = 0.0921 = 9.21%
    which is a 2.7:1 ratio (water to NaOH ratio)


    Assume that we use 1:1 ratio (water : NaOH) (50% NaOH)
    then NaOH = 2.241
    Water = 4.482

    initial lye percentage in soap = 2.241/ (2.241+2.241+ 16) = 2.241 / 20.482 = 0.1094 = 10%

    If your ratio is 1:1 versus 2.7:1 the you are starting with a soap with a higher concentration of NaOH.
     
  11. Dec 11, 2013 #11

    rjalex

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    LOL yafa you lost me, but my soaps come out well with those SoapCalc values (no separation, mild and season well) so no worries :)
     
  12. Dec 11, 2013 #12

    The Efficacious Gentleman

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    Yafa, I'm not sure that a 1:1 ratio would then have different amounts of lye and water. 1:1 would be 1 oz water to 1 oz lye. 2:1 would be 2 oz water to 2 oz lye.
     
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  13. Dec 11, 2013 #13

    dixiedragon

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    I never drop the soap calc number below 36%, and sometimes I will up it to 40%. The few times I have tried to seriously reduce the water, it has not gone well for me. I wasn't using soap calc then, I used the calculator at The Sage and I would pick the lowest water value. I would end up with an undissolved lye cake at the bottom of the pitcher, or the soap would be too thick, etc. I am not in a big hurry for my soap to get hard. It's hard enough to cut in 24 hours or less, and that's all I really want.
     
  14. Dec 11, 2013 #14

    rjalex

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    ditto
     
  15. Dec 11, 2013 #15

    seven

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    LOL!! i was gonna say the exact same thing when i read yafa's post, but i was too embarrassed to admit that i am hopeless when it comes to math/numbers. i got Ds and Es quite a lot in math back at school :oops:

    i think you meant 2 oz water to 1 oz lye, right?
     
  16. Dec 11, 2013 #16

    yafa

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    Just to clarify:

    We are not changing the amount of NaOH, this is always constant ( since it depends on the Saponification values for the oils), What we are doing is only changing the amount of water. Each one of us prefers a certain concentration ( within the range). This is why we end up with a different concentration of lye ( 1:1 is 50% NaOH in Water solution (50% lye solution)), 2:1 is 2 water to 1 NaOH, which will be 33% lye solution (33% NaOH solution).
     
  17. Dec 11, 2013 #17

    The Efficacious Gentleman

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  18. Dec 11, 2013 #18

    rjalex

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    So clear I'm putting on sunglassses ! :)
     
  19. Dec 12, 2013 #19

    DeeAnna

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    "...I can't think why they are using it, the only reason I can think of, is to give you an idea of how much water do you have compared to the weight of oil...."

    My understanding of the origin of the "% by weight of oils" idea --

    I don't see this idea in the industrial soapmaking tomes of the 1800s and early 1900s. I don't see it in the recipes printed on the old bottles of lye that my grandmother used (1960s and earlier).

    I suspect this concept was developed in the 70s and 80s when handcrafted soap makers were trying to develop the ability to design safe recipes for CP soap rather than just blindly follow the recipes on the lye bottle. The lye amount is calculated on the weights of the fats ... so I suspect their thinking was "Why not also calculate the water amount based on the total weight of fat?"

    Not everyone has a chemistry background, so this general pattern of thinking may have made perfect sense to those soap makers. Whether it makes sense to you and me is one thing ... but this approach might have made perfect sense to those original soap makers. And so now we have this odd concept well entrenched in the soap making methods of today.
     
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