How do I calculate the lye

[Sunibee]

My help got me some left over oils and asked me to make her some soaps. I had gifted her a few n she loved them.. I added charcoal to the oils. She thinks they would be more of sunflower, canola and rice bran. I normally go with 13% lye when oils are not known . Am I right in going with the same % for this batch ? I normally add charcoal chunks to my oils to deodorise them .. I make my kitchen bar soap/ dusting cloth washing soap etc with my left over oils .

 

[KiwiMoose]

You should always use a soap calculator

 

[DeeAnna]

...I normally go with 13% lye when oils are not known . Am I right in going with the same % for this [sunflower, canola and rice bran] batch ?....

Like KiwiMoose, I would rather use a so@p recipe calculator rather than assume a number for the saponificaton value. I add a second vote to her recommendation that you learn to use one.

But if you're not interested in doing that, then, yes, 0.13 is probably a safe choice and sufficiently accurate enough for a blend of these 3 fats.

The saponification value for canola is 0.133, for sunflower is 0.136, and for rice bran is 0.128. I got these numbers from a so@p recipe calculator by the way.

 

[Sunibee]

Like KiwiMoose, I would rather use a so@p recipe calculator rather than assume a number for the saponificaton value. I add a second vote to her recommendation that you learn to use one.

But if you're not interested in doing that, then, yes, 0.13 is probably a safe choice and sufficiently accurate enough for a blend of these 3 fats.

The saponification value for canola is 0.133, for sunflower is 0.136, and for rice bran is 0.128. I got these numbers from a so@p recipe calculator by the way.

Thank you DeeAnna. . I do use Thesage.com . For calculating other properties . But for lye value I preffer to do it manually.
My question is I'm the case of not knowing what oils , the volume of each .. and these are used oils mixed into a bottle . I guess 13% is a good no to follow .., my

You should always use a soap calculator

Thank you..

 

[DeeAnna]

I can't quite wrap my mind around why one would want to calculate the lye weight by hand yet use a so@p recipe calc to do all the other number crunching. The calculations are exactly the same when a computer does the work, with much less chance of math errors.

I would think by comparing your answers with the calc's answers, you would see there's no particular virtue or benefit to doing the math by hand. But to each their own.

 

[The_Phoenix]

If I understand you correctly, you have a solution that contains a mixture of oils. Correct?

And you do not know the percentages of the individual oils contained in the solution. Correct?

And you are considering guessing at the percentages in order to come up with your own quantity of lye needed to saponify the mixture of oils. Correct?

 

[DeeAnna]

Not the OP, but I can tell you the answers to the first 2 questions are "yes," and the answer to the last question is "it's not necessary." All you need to know is the total weight of the fat blend, not the percentages of the fats in the blend.

It's not a bad plan to use an estimated average sap value of 0.13 for this oil blend. The sap values range from 0.128 to 0.136 for the different fats, so 0.13 is sufficiently accurate and safe for the purpose of the calculations. In addition, since NaOH is never 100% pure, this "hidden" superfat builds in an additional few percent to the actual superfat.

Agreed it's not as precise a method as most people (including me) prefer to use, but it will still make a safe soap.

 

[Sunibee]

If I understand you correctly, you have a solution that contains a mixture of oils. Correct?

And you do not know the percentages of the individual oils contained in the solution. Correct?

And you are considering guessing at the percentages in order to come up with your own quantity of lye needed to saponify the mixture of oils. Correct?

The_Phoenix , yes . That is my worry when I make it at home..I measure my oils n what kind of oil added , date etc when I add the oils . Am pretty sure my maid does not keep count. But she wants me to help her out with soap

Not the OP, but I can tell you the answers to the first 2 questions are "yes," and the answer to the last question is "it's not necessary." All you need to know is the total weight of the fat blend, not the percentages of the fats in the blend.

It's not a bad plan to use an estimated average sap value of 0.13 for this oil blend. The sap values range from 0.128 to 0.136 for the different fats, so 0.13 is sufficiently accurate and safe for the purpose of the calculations. In addition, since NaOH is never 100% pure, this "hidden" superfat builds in an additional few percent to the actual superfat.

Agreed it's not as precise a method as most people (including me) prefer to use, but it will still make a safe soap.

Thank you DeeAnna

I can't quite wrap my mind around why one would want to calculate the lye weight by hand yet use a so@p recipe calc to do all the other number crunching. The calculations are exactly the same when a computer does the work, with much less chance of math errors.

I would think by comparing your answers with the calc's answers, you would see there's no particular virtue or benefit to doing the math by hand. But to each their own.

Haha...I muck around a lot.. I find the difference bet soap calc n mine to have a difference of almost 5 to 8 gms of lye..I like using certified-lye.com & a couple of others for sap value ..

 

[earlene]

Is that 5-8 grams of lye difference based on a huge batch of oil or a smaller batch of oil? I suspect you have a reliable source for your SAP values that you use in your calculations. Do you factor in a Superfat, or none?

I have noticed minor differences in some calculators, but only once or twice have I found a major difference, and I don't recall which one (or two) were so glaringly different (it was probably only for one or two oils where I found a glaring difference, though.)

Then the other thing is that not every calculator allows fine-tune adjustments by the user; some work differently than others, I have discovered. I prefer one that allows the user to make as many adjustments as they prefer (like SF, Lye Concentration or Water to Lye Ratio, Use of dual lye, etc.) without treating the user like they don't have options or cannot make safe choices with these options. And I prefer to use one that makes changes on-the-fly, meaning that there is not an additional "calculate" step that takes the user to a second page, but that the calculator gives results without having to move to a second page.

I compared the results for the HSCG calculator, (which I have never actually used before) versus Soapmaking Recipe Builder & Lye Calculator using equal parts of the three oils you mentioned above (canola, RBO, sunflower) at 5% SF & only 500 grams of oils, and the amount of lye was close enough for a small batch (0.2 grams difference between the two) that it would not make a noticeable difference.

But even when I increased the recipe to a larger batch, 5000 grams of oils (or 10 times larger batch, the difference was a full 2 grams different between the two, but still not enough to make a noticeable difference.

Which is why I am wondering how you are coming up with that much of a difference. Is it with any specific oils that you get such a big difference, or is it with all of them?

I truly am curious.

 

[Sunibee]

Is that 5-8 grams of lye difference based on a huge batch of oil or a smaller batch of oil? I suspect you have a reliable source for your SAP values that you use in your calculations. Do you factor in a Superfat, or none?

I have noticed minor differences in some calculators, but only once or twice have I found a major difference, and I don't recall which one (or two) were so glaringly different (it was probably only for one or two oils where I found a glaring difference, though.)

Then the other thing is that not every calculator allows fine-tune adjustments by the user; some work differently than others, I have discovered. I prefer one that allows the user to make as many adjustments as they prefer (like SF, Lye Concentration or Water to Lye Ratio, Use of dual lye, etc.) without treating the user like they don't have options or cannot make safe choices with these options. And I prefer to use one that makes changes on-the-fly, meaning that there is not an additional "calculate" step that takes the user to a second page, but that the calculator gives results without having to move to a second page.

I compared the results for the HSCG calculator, (which I have never actually used before) versus Soapmaking Recipe Builder & Lye Calculator using equal parts of the three oils you mentioned above (canola, RBO, sunflower) at 5% SF & only 500 grams of oils, and the amount of lye was close enough for a small batch (0.2 grams difference between the two) that it would not make a noticeable difference.

But even when I increased the recipe to a larger batch, 5000 grams of oils (or 10 times larger batch, the difference was a full 2 grams different between the two, but still not enough to make a noticeable difference.

Which is why I am wondering how you are coming up with that much of a difference. Is it with any specific oils that you get such a big difference, or is it with all of them?

I truly am curious.

Earlene , I don't factor in SF ,, For any batch big or small I get a big difference..I think it's the coconut oil ..plus I like using dual lye many a time . . Actually the-sage.com is more dual lye friendly . Personal. Preference for me