Water can be measured as a % of oil weight or as a relationship to lye amount. A 33% lye solution is roughly 1 part lye to 2 parts oil.
Yes- Judy brings up an excellent point. I should clarify that when I say I use a "33% lye solution", that it's
not the same as changing SoapCalc's default "water as % of oils" box from 38% to 33%.
Instead of using the "Water as % of Oil" box on SoapCalc, I use the "Lye Concentration" box, which bases my water amount on my lye amount instead of my oil amount, which actually makes much more logical sense to do since it's the lye amount that determines how much water is needed (instead of the oil amount being the determining factor).
Here is an excellent description of why I choose to base my water on the lye amount instead of the oil amount (see page 3 of the following PDF):
http://rivercitysoaps.com/dwcp/dwcp.pdf
A case in point as to why the 2 different methods are different and should never be confused with each other:
A 33% lye concentration/solution for a 100% coconut soap equals out to a 35.4% water to oils amount on SoaCalc,
....but for a 100% Castile batch, a 33% lye concentration/solution shows up as a 26.13% water to oils amount on SoapCalc.
Did you see how the water-to-oil % is radically different in the 100% OO soap as compared to the water-to-oils % in the 100% CO soap, even though the water to lye ratio remains the same?
Again, please refer to the link I provided to see Roxanne's most excellent explanation of the radical difference between the 2 and why I believe that the better and more consistent method to figure water amount is to base it on the lye instead of oils.
I believe her explanation will help to explain the reason why certain recipes that work great for one person, work horribly for another....... not because of soap fairies, but because we are all assuming that when a person says that they are using 33% water or whatever other % water, that they are using the same method of determining water as you, when the opposite may actually true. That's why I always include the words 'concentration' or 'solution' whenever I disclose my water amount. It differentiates the one from the other.
IrishLass