Hot Process Loses Weight From Start of Process

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user 49910

Well-Known Member
Mar 13, 2021
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First let me state that I know that soap will lose weight when curing over a several weeks period such as with cold process. It is evaporation of water from the bars.

Why would a batch of dual-lye hot process that only took about 20 minutes from start to complete saponification lose about 15% of it's weight? My batch weight to begin was 708 grams in total, the ending weight was 602.35 grams. I did both a "Zap" test and a 1 gram of paste in 99 grams of distilled water pH test (I know, I know... not that reliable, but I did use a pH meter.)

I that short time span I do realize that there is some evaporation. I did cover the crock pot with plastic wrap plus the lid immediately after the trace went pasty. After about 20 minutes and the pH test I added the sodium lactate (1 teaspoon) and the 15 grams of fragrance oil. Still there was a net loss of 105.65 grams of weight or 3.73 ounces. I estimate about 1 ounce was clinging to the interior of the crock pot, hand whisk, and small silicone spatula; even though I was quite meticulous to get every last smidgen, if possible.

So, even in that short time span, there was an evaporation of approximately 2.73 ounces of water or about 5.46 Tablespoons.

Since this is a soft, paste type of soap would it be correct in my thinking to increase the distilled water amount by 15% to account for the water loss?
(Yes, I did not take into account the paste stuck to utensils and pot of approximately 1oz or so.)

Thanks in Advance!

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