Ingredients in Soap Making + Calculating
These are the common ingredients for soap making and I'll teach you how to calculate how much ingredients you need!
Base oils: hard/saturated & soft/unsaturated
For cold processed soap, it is advised to use from 3-7 types of oils.
You would need at least 3 basic oils - at least having one hard oil to make sure your soap stays together for a longer period of time!
Essential oils: natural aromatic compounds in plants with therapeutic effects
Natural additives:
There are also additives like rose clay, coffee grounds etc
Before I start showing you how to make cold process soap, depending on the weight of the mould being use (I used a 500g mould), we need calculations of weight and percentage of each oils, amount of lye to add in, knowing the iodine value (INS) and amount of distilled water need to be used
Here is the Saponification Value and INS
the NaOH column shows the amount of lye is needed per gram
KOH is Potassium hydroxide (used for liquid soap)
INS is the hardness of soap
for a soap INS 120 and above (preferably highest at 170), the soap can be used for facial soap.
Any soap INS higher than 170 contains "hard" oils as shown in the base oil diagram - only can be used for body and feet.
To Calculate oils
The amount of each oil = total oil weight x % of oil
Eg 55% of EV coconut oil = 350g x 0.55 = 192.5g
*EV refers to Extra Virgin
Depending on what mould you are using, use 70% of the mould weight is the total weight of the oil need to be used.
also note that you will need at least 3 basic oils and should limit to 7 oils, why? it is not to confuse. The more oils, the more complication - unable to check what went wrong.
To Calculate Lye
Individual oil is needs a specific amount of lye to saponify the oils (hardness of the soap). Referring to the INS table to calculate the amount of lye needed
The amount of oil x NaOH of oil = amount of lye needed
Eg EV Coconut oil = 192g x 0.19g = 36.48g
( we round down or up the oil weight to make it a full value for easier calculations)
To Calculate INS
Each oil has it's own iodine value (INS) or saponification value. INS value will influence the softness of hardness of the final soap. Usually INS value of around 125 - 170 is ideal for face and body soap.
INS Value = individual weight ÷ total oil weight x INS of individual oil
Eg EV Coconut oil = 192÷350 x 258 = 141.53
* INS of individual oil can be referred to Saponification value and INS table
To Calculate Water
To calculate the amount of distilled water needed is calculated by 2 ways:
Way 1: weight of lye x 2.0 to 2.5 ratio
or
Way 2: Weight of lye ÷ 0.3 - lye weight
Eg. 57.345 x 2.3 = 131.89g
I'm using a 500g soap mould. To get the total weight of the soap bar of 500g, I will need 350-400g of oil, 59g of sodium hydroxide and 124ml of water
Here is my calculation for my soap recipe
The good thing about hand made cold process soap is that the recipe that you use, can be adjustable to your fitting, you can decide whether to increase or decrease certain oils, or add in another type of oil. It is customisable to you and your preference!
Check my next post for how to make cold process soap here!
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