Calculating SAP By Hand ..

I had a long power-cut the other day and it brought home just how important it is to know how to do this ..

OIL	FORMULA %	WEIGHT	SAP Value	NaOH NEEDED
Olive Oil	65	1300 x	.134	= 174.2
Coconut Oil	15	300 x	.183	= 54.9
Shea Butter	15	300 x	.128	= 38.4
Castor Oil	5	100 x	.128	= 12.8
TOTAL NaOH				280.3
REMOVE LYE DISCOUNT (aka) SUPERFAT	eg: 5% SF X.95	OR - 5%		= 266.28gm

So all you have to do is work out your oil weight, and multiply that with the specific oils SAP Value ..

Do this for all the oils in your formula and then add them all up ..

Then remove your desired Lye Discount % either by multiplying or dividing ..

Again it's just the oil weight multiplied by it's SAP Value:
1300gm Olive x .134 SAP Value = 174.2gm NaOH ..
Then remove your Superfat %

And just in case your supplier can't provide the SAP for your oils (they will alter slightly with each batch), here are some sites you can get a general range from - print these out and store somewhere safe!!

Oh, and make sure you get the NaOH SAP not the KOH SAP, unless you're making liquid soap!
*click links*
{ SoapCalc.net }
{ soaperschoice.com }
{ soapguild.org }

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Now your Water is the total Lye amount divided by the % you want your solution strength to be, and then multiplied by the remainder of the the 100(%) ..

28% LSS (28/72)
30% LSS (30/70)
33% LSS (33/67)
35% LSS (35/65)
38% LSS (38/62)
40% LSS (40/60)

So for a 33% LSS using the above recipe:
[b]266.28 ÷ 33% : 806.90 x 67% : 540.62ml[/b]

Or if you go to Soapcalc and type in your desired Lye Solution Strength eg: 33% - it will give you the Lye to Water ratio .. So if you have that you can just multiply it with your Lye weight ..


Hope This Helps Someone :D