Lye Calculators Discrepancies

[gutreactor]

Recipe
Apricot Kernel Oil 6 g
Castor Oil 60 g
Coconut Oil, 76° 834 g

Going with 1% SF to make sure there's no free lye for my very first transparent soap. I ran the recipe through all these calculators & still not sure how much lye to use. Any ideas from anyone with more experience to make sure there's no free lye even if it doesn't come out glass clear?

Discrepancies >
https://saponicalc.com/calculator
Ingredients Ounces Pounds Grams Kilograms
Water 10.48 oz 0.65 lb 297 g 0.3 kg
Sodium Hydroxide (NaOH) 5.63 oz 0.35 lb 159.55 g 0.16 kg
Apricot Kernel Oil 0.21 oz 0.01 lb 6 g 0.01 kg
Castor Oil 2.12 oz 0.13 lb 60 g 0.06 kg
Coconut Oil, 76° 29.42 oz 1.84 lb 834 g 0.83 kg
http://www.thesoapcalculator.com
Superfat 1% Water : % of oils 33
Basic ingredients grams %
Apricot Kernel Oil 6 1
Castor Oil 60 7
Coconut Oil, 76 deg 834 93
Water 297
Lye (NaOH) 160
http://www.northcountrymercantile.com/soapmakinglibrary/lye-calculator/
Ingredients:
6 grams of Apricot Kernel Oil
60 grams of Castor Oil
834 grams of Coconut Oil (76 degree)
156.47 grams of sodium hydroxide (NaOH) at 1% superfat
11.91 oz of water (by weight) [337.64g]
http://www.soapcalc.net/calc/soapcalcwp.asp
Oil/Fat % Pounds Ounces Grams
Apricot Kernal Oil 0.67 0.013 0.21 6.00
Castor Oil 6.67 0.132 2.12 60.00
Coconut Oil, 76 deg 92.67 1.839 29.42 834.00
Water 0.655 10.48 297.00
Lye - NaOH 0.352 5.63 159.75
https://www.savvyhomemade.com/soap-calculator/
water/lye ratio 2/1
lye 155.41g
water 310.82g
https://www.thecosmeticslab.com/soap-recipe-lye-calculator
Apricot Kernel Oil 6 g 0.7%
Castor Oil 60 g 6.7%
Coconut Oil, 76 deg 834 g 92.7%
Water and lye
Water 297 g
Lye (NaOH) 124.8 g [WAY OFF FROM THE REST OF THEM.]

 

[MelissaG]

Try soapcalc.com or soapmakingfriend.com. They are all usually off a bit, not sure why.

 

[bookworm42]

SAP numbers are based off an average. Different websites use different numbers for that average. I've used soapcalc and soapmaking friend with no issues.

 

[Mobjack Bay]

The amount of lye calculated/needed will also depend on the assumed lye purity. The calculators vary a bit in this regard, with some allowing you to change the purity. From the links you provided above, the cosmetics lab calculator assumes 99.8% lye purity and the savvy homemade calculator assumes 97% purity. The SMF calculator, which is what I use, assumes 99%.

 

[gutreactor]

Try soapcalc.com or soapmakingfriend.com. They are all usually off a bit, not sure why.

that was one in the list I thi9nk I'll go with about 159.5g

 

[gutreactor]

SAP numbers are based off an average. Different websites use different numbers for that average. I've used soapcalc and soapmaking friend with no issues.

Maybe I'll go with soapcalc & lower the lye just a bit.

 

[gutreactor]

The amount of lye calculated/needed will also depend on the assumed lye purity. The calculators vary a bit in this regard, with some allowing you to change the purity. From the links you provided above, the cosmetics lab calculator assumes 99.8% lye purity and the savvy homemade calculator assumes 97% purity. The SMF calculator, which is what I use, assumes 99%.

Whoa I didn't know that. Good to know

 

[DeeAnna]

As others are saying, the data sets and parameters aren't identical for all the calcs in existence.

Unless you test the saponification values and fatty acid content of each of the fats you're using and test the purity of the lye you have, you don't have a reasonable basis for deciding which calc is most accurate for the ingredients you have on hand at the moment.

So maybe the answers you're getting from Soapcalc are the most accurate for your ingredients. Or maybe another calc is more accurate. But unless you test your ingredients, you'll be purely guessing that the answers from one calc are more suitable than answers from another.

Honestly, the best solution here is to stop with the exhaustive comparisons. Pick one reputable calc, learn how to use it, and accept with the answers it gives you. Or learn to test your ingredients and create your own calc using that test data.

You said you feel the need to "lower the lye just a bit", but you didn't explain how you planned to do that. I'd suggest doing this by raising the superfat percentage a reasoned amount, rather than changing the NaOH weight by some arbitrary amount. If you raise the superfat percentage, you're using the system the way it was designed to be used. Also you can replicate those modifications for future batches.

 

[gutreactor]

As others are saying, the data sets and parameters aren't identical for all the calcs in existence

Thanks for the advice DeeAnna. I will use bit more oil. I'm not advanced enough to know how much lye I'd need according to sap value. I didn't see anywhere on the calcs to put in lye purity but I'll be getting 99.

 

[DeeAnna]

Increasing the weight of fat for a given weight of alkali is the same thing as lowering the weight of lye for a given weight of fat. The best way to accomplish this is by increasing the percentage of superfat.

The calculations done by a soap recipe c@lculator provide the weight of alkali for the weights of the fats you want to use, so that's not something you have to worry about. The only reason why you need to know saponification values is if you want to do the calculations by hand or create your own personal calculator.

Many online calcs assume a given NaOH purity. Pick one that is based on an NaOH purity close to your actual NaOH purity -- see Mobjack Bay's comments. Or use one like LyeCalc that allows you to enter the purity %.

 

[gutreactor]

Increasing the weight of fat for a given weight of alkali is the same thing as lowering the weight of lye for a given weight of fat. The best way to accomplish this is by increasing the percentage of superfat.

I did think that increasing the fat was the same thing as lowering the lye. A while back I tried LyeCalc & the 'Done Picking Oils' button was unresponsive in the beginner section. I just tried again & same thing. In the regular section... I guess I'm technologically challenged. I couldn't find the purity % or even the NaOH, water as % of lye or superfat %.
I like https://saponicalc.com/calculator & http://soapcalc.net/calc/soapcalcWP.asp
Since I want to make transparent soap which is usually 0% SF, & I put in 1% to be sure there's no free lye, I think I'll be OK with the recipe. It's not critical that I get glass clear.