calculate Lye
Manually calculating the lye in soap making
SAP values are the traditional numeric values that allow you to calculate the precise amount of sodium hydroxide required to fully saponify a given weight of oil/s.
For example:
Step 1.
24 oz of olive oil (SAP olive oil = 135,3)
16 oz of coconut oil (SAP = 191,1)
16 oz of palm oil (SAP = 142 )
4 oz of shea butter (SAP = 128 )
2 oz of castor oil (SAP = 128,6 )
__________________
62 oz of oils
Step 2.
(24 oz x 135,3)+(16 oz x 191,1)+(16 oz x 142)+(4 oz x 128 )+(2 oz x 128,6 ) =
3.247,2 + 3.057,6 + 2.272 + 512 + 257,2 = 9.346 oz Lye (9.35) is needed to fully saponify of 62 oz of oils.
Note: when rounding the number, always rounding up
Step 3.
So, the 9.35 oz will be saponified oils to become a perfect soap, but it will be not moisturizing to the soap. To make a final calculation to reduce 5% to 10% from the total lye, or discount lye is the same thing for superfatting. Just to ensure your soap not too much lye. So, the 9.35 x .95 = 8.882,5 = 8.88 oz Lye (discount 5% ) for 62 oz oils.
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