Converting an Existing Recipe to use a lower % of Alcohol.

You found the perfect Transparent soap recipe but it requires 190 Proof Grain Alcohol and all you can find is 150 Proof. Do not worry, there is a way to make it work. 190 Proof Alcohol is 95% Alcohol and 5% water. 150 Proof is 75% Alcohol and 25% water. What happens here is that you are introducing more water in the recipe when you are using the weaker Alcohol, so what you have to do is discount the water for the lye and the sugar solution in order to compensate. You also need to use more Alcohol because the one you are using is a weaker solution. Here is how you do it:

First divide .95 by .75 to find the multiplier. (.95/.75 = 1.26)

Let's say your recipe requires 10 oz of 190 Proof Alcohol, multiply 10 by 1.26 = 12.6, so you will need 12.6 oz of 150 Proof Alcohol.

Now let's address the excess water: If the requirements for the 95% Alcohol were 10 oz of alcohol, that means we are introducing .5 oz of water into the recipe. (10 x .05), but when we use 12.6oz of Alcohol at 75%, (12.6 x .25 = 3.15) we introduce 3.15 oz of water into the recipe. Substract .5 from 3.15, that means we have 2.65 oz of excess water.

Let's say that your recipe required 14 oz of water total (water for the sugar solution + the water for the lye), then substract 2.65 from 14 = 11.35, that means that you can use 11.35 oz of water in your recipe. I like to mix my lye with at least 1.5 times it's weight in water, let's say you need 4 oz of lye, then you would mix it with 6 oz of water. That keeps the soap soft enough after the gel stage so you can stir it. You are left with 11.35 - 6 oz = 5.35 oz of water for the sugar solution. You can round up those numbers, but use as little water as possible in the sugar solution, you do not have to use the whole amount.