used 3 calcs and get 3 different lye amounts

[normajean999]

Hi all. I was wondering if someone could help me figure out why I am getting different amounts using different calculators. I was using brambleberry's calc initially because it was easy. I select solid soap, grams, and enter 300 for Olive Oil and 300 for Coconut Oil 76 deg, select 5% discount and I get 88.92g for lye. I am using NaOH btw.

When I use soapcalc 38% water, 5% discount, 300g each for OO and CO I get 90.83g NaOH.

And using thesage I get 91.02g.

So I am confused as to why I am not getting the exact same number each time. I mean this is math and science so it shouldn't vary lol. What am I doing wrong?

 

[coffeetime]

Sap values are averages, so different calculators would have slightly different numbers based on their sources. That's why recipes always have a superfat %- to allow for a margin for error. I would use the average which would be 90 grams and a minimum 5% superfat.

 

[boyago]

The calculators use a given number for SAP values of the oils listed. The numbers may vary a little depending on the source. Also I think the oils themselves vary a little too since no two coconuts will produce the exact same fatty acid content. The variation you mentioned is .19 of a gram so that's pretty close over 600g of oil.
** edit ** whoops didn't see your first number there so 2.1g but like coffeetime said the super fat should take care of you.
Side note 50% coconut oil seems a little high for a regular soap. May be drying if that is your oil combo. I'd back it off a little adding some of that to another oil.

 

[IrishLass]

Ditto what Coffeetime and Boyago said.

You're not doing anything wrong. Lye calculators often differ slightly from each other because SAP numbers often differ slightly from each other due to where the oils/fats were sourced. Because of those slight differences, the SAP #'s that the calculators choose to go with are not exact, but based on an average range of the different SAP values for any particular oil/fat (some calculators calculate the average from a wider range, and some from a narrower range). That's why most good calculators suggest using a 5% superfat for our recipes. That 5% cushion of extra fat will cover over the differences and guard our soap against the possibility being lye heavy.


IrishLass

 

[Susie]

Whatever soap calculator you are comfortable using, use consistently. Period.

I had the same issue when I was new(er) than now. Just realize that most of us use SoapCalc for bar soaps, so any questions you ask will result in us using SoapCalc to evaluate. I stopped being quite so confused about NaOH amounts when I finally learned SoapCalc.

 

[The Efficacious Gentleman]

As above. But you might also want to look at upping the superfat or adding in another oil - currently you have 50% coconut which a lot of people would find far too drying. You might not, but the odds are that you will.

So you could use a higher superfat or change the recipe so that the coconut is about 20% or so

 

[DeeAnna]

I totally agree with what the others have said. Even though the math doesn't change, the properties of the fats do change depending on the weather during any particular growing season, the regional climate (arid, temperate, natural rainfall, irrigation), the variety of plant or animal, diet and soil fertility, etc.

For example, I have one set of analyses of of lard samples that show an average oleic acid of 33%. Soapcalc's data shows oleic at 46%. Who is right? They both are.

So the soap recipe calcs do their best, given the natural variability of the fats we use. I seem to recall soapcalc uses an average of several sources for its data. Not sure about the data in the other calcs, but obviously the numbers vary from calc to calc with some good reason.

If you buy fat from a particular source that provides saponification values for their products, use those data if you can. Soapers Choice is one distributor that does this.

 

[normajean999]

Thank you all for the responses! I appreciate all your comments and advice.