Which calculation to use? And how exact?

[SoapMakerDeluxe]

I took the advice of this forum and ran the following soap recipe (from Soap Queen's eBook) through a calculator:

6 oz Coconut oil
6 oz Palm oil
9 oz Olive oil pomace
1 oz Castor oil
7 oz water
3.0 oz lye
1.4 oz fragrance

When I ran it through the SoapCalc calculator, I got the following recommendations for water and lye:

8.36 oz water
3.12 oz lye

My questions are: so which water - lye combo do I use? And do I have to get 3.12 exactly or will rounding to 3.1 and 8.4 for lye and water respectively work?

Thanks in advance.

P.S. Also, there are three options for coconut oil, like 76 degree coconut oil, etc. I have no idea which one I'm using.

 

[new12soap]

All lye calculators are going to be a little different because they use averages for SAP values. Either one is probably fine, just make sure your amounts are the same, superfat is the same, lye concentration etc are all the same.

Yes, you rounded it exactly correctly. Round the lye down and the water and oils up. You would be better off measuring in grams if you can.

As for your coconut oil, 76 and 92 have the same SAP value, so if yours is solid or semi-solid at room temperature you can just use CO 76. If yours is a clear liquid all the time, it's fractionated. The stuff you get in the grocery store is 76.

 

[LunaSkye]

My questions are: so which water - lye combo do I use? And do I have to get 3.12 exactly or will rounding to 3.1 and 8.4 for lye and water respectively work?

I usually round up the water weight while rounding down the lye. I never really had a problem doing that.

P.S. Also, there are three options for coconut oil, like 76 degree coconut oil, etc. I have no idea which one I'm using.

EVCO (and I believe refined CO) is the same as 76 degree CO. 76 degree CO would be solid around that temperature and would melt if it is 80 degrees F. 92 degree CO would still be solid at 80 degrees F and fractionated would be liquid (it serves as a good carrier for EOs so I've read).

 

[girlishcharm2004]

Personally, I print out the recipes from SoapCalc and put it in a binder, so I would use the SoapCalc recipe for lye and water so I know exactly what I did and could retrace my steps if something went wrong. If you happen to write it out by hand, then I'm sure you could use either since they are so incredibly close. SAP values range depending on the weather the crop was grown in, the amount of unsaponifiables, and even age of the plant at harvest. SAP values are an average.

 

[marilynmac]

Did you use the same superfat % in each calculator? higher superfat% will call for less lye.

 

[DWinMadison]

I use soapcalc, but I always use the grams calculation instead of ounces. It's about 3 times more accurate. I also use standard rounding, 5 or greter goes up to the next number b

 

[Susie]

I understand you are trying to get this in your head with some sort of firm rule. But, when they say round down for lye and up for everything else, that needs to be your rule. It is so that if you are making very small batches, then you don't throw off your superfat amount and end up with a lye heavy soap. If you round up the lye and down the oil, you take chances if your superfat is low or your scale is off a tiny bit.(A US nickel weighs 5 grams, so throw a nickel in with your soapmaking equipment and check it every time.)

Also, always run every recipe through a lye calculator for yourself. I am with girlishcharm2004. I print every recipe, take notes right on that sheet, record any additives, etc. Then I put it in my soaping binder. That way, I always can refer back to it.

 

[DeeAnna]

Soap calculators use average saponification values that are based on a typical range of values for each soaping fat. The numbers vary slightly from calc to calc depending on where they get their numbers. Like the others who have chimed in on this thread, I recommend picking a calc that you like the best and stick with it.

As you get experience with that particular calc, you'll learn the general "drift" of that particular calc and can develop your recipes accordingly. The point is to become as consistent as possible in formulating recipes, and sticking with a calc is one aspect of consistency.

The other alternative to using these estimates is to actually test each container of fat for its true saponification value. That's not something most people are going to want to bother with, although it can be done by a determined hobby soaper with some study and practice.

If you have your own soap recipe calc, as I do, you can sometimes find out the recommended sap values for your supplier's products and use those values for a somewhat more accurate result. I know Soaper's Choice has a list of sap values for their fats, for example, and I've put those sap values in my calc.

This idea of using average sap values may seem horribly inaccurate to some, and I suppose that is true. But error is inherent in every natural system, including soap making. I try to be as accurate and careful as possible when I weigh out my ingredients and do my soaping, even though I know full well that my numbers aren't necessarily 100% perfect to begin with. But I figure I don't need to be adding even MORE error by being sloppy too!