I really want to try this, but I am having a very hard time trying to adapt my [50% lye] masterbatch to say, a 40% lye concentration, particularly with the added KOH. Using the advanced search I have been unable to find any answers to this question. It doesn't mean they are not here, but I just cannot find them. I think I can do the calculations for a 40% concentration easily enough with just NaOH, but with a 5% KOH and 95% NaOH, how would I do this? I am at somewhat of a loss. Do I use the NaOH water and ignore the KOH water recommendations? Or is there a formula for figuring out how much water for the KOH separate from the amount needed for the NaOH, thus having to add the two together? Well this is how far I have gotten so far: 95% NaOH for this 32 ounces of OO = 110.9 grams 5% KOH = 9.1 grams (per Soapee) Or is it 8.1 grams (I get 8.1 if I use the 0.713 number as the divisor in this post) That's about as far as I get, because I don't know where to go with the water. Soapee says to use 179.9 grams of water total. Okay, so if I do that, then here's what I will do with my 50% masterbatch: 221.8 grams of 50% Lye solution 69 grams of additional distilled water 9.1 grams of KOH (per Soapee) BUT other calculations lead me to 8.1 grams (1.403 as a multiplier or 0.713 as a divisor) Both MMS & SummerBeeMeadow also come up with 8.1 grams KOH, so I am thinking 8.1 grams is correct and not the 9.1 I get in Soapee (or maybe that's because the KOH is set at 90% purity in Soapee?) Which of these numbers correct for the KOH? Is the additional water amount correct, and how does one determine that for a mixed lye soap? ~ ~ ~ ~ Also at one point I think I found a post where someone (don't remember who, but I think it was one of the more sciene-minded members) posted a little chart about how to figure out how much water to add to a 50% lye pre-mix (masterbatch) solution to come up with respective concentrations. I believe it listed them like for 40% add, for 35% add, like that. Anyway I can't find it now and I thought I bookmarked it. So perhaps it was my imagination.