How long is lye active for in CP soap
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Lye is active in soap until the process of saponification is complete, so until the soap cools (this is provided that you have a correct recipe, and have correctly measured and added all of your ingredients.)... Usually this is 18-24 hrs.
After this it is advised to let it cure 4 to 6 weeks, during this process the excess H20 (water) will evaporate out of the bar,making it more firm and adding to how long it will last in the shower or bath. During this time the soap will also become more mild and its properties such as lather should increase as a result of the higher concentration of soap molecules present in the bar (remember alot of H20 has evaporated out of the bar, hence there is less water and more soap given the mass of the bar)
After this it is advised to let it cure 4 to 6 weeks, during this process the excess H20 (water) will evaporate out of the bar,making it more firm and adding to how long it will last in the shower or bath. During this time the soap will also become more mild and its properties such as lather should increase as a result of the higher concentration of soap molecules present in the bar (remember alot of H20 has evaporated out of the bar, hence there is less water and more soap given the mass of the bar)
This is not a very scientific answer, but I consider the lye to be sufficiently inactivated right at the point where there is no longer any 'zap' when the tongue test is applied to the finished soap. In my soaping experience this can take from as little as a few hours to as much as a week, depending on the formula, the soaping method used (CP or HP), and whether the soap went through the gel-stage or not. At that point (when it has ceased to zap) it is safe to use, but I am convinced that even though the lye has ceased to zap, that there are still micro chemical reactions going on in the finished soap during the weeks following (usually a 4 to 6 week period) that cause the soap to get harder and harder (water evaporation), milder and milder and bubblier and bubbblier. Whether the mildness and bubbliness is due to micro-active lye or something else, I don't know. What I do know is that the earliest that the soap is considered safe to use is when it has ceased zapping during the tongue test.
IrishLass
IrishLass
donniej
Well-Known Member
It depends on temperature, superfat, how well you mix, etc...
I'd say 24 hours will nuetralize most (if not all) of it. The only way to tell for sure is with a PH indicator like phenolpthalien.
I'd say 24 hours will nuetralize most (if not all) of it. The only way to tell for sure is with a PH indicator like phenolpthalien.
timewise it's hard to say - some fatty acids react faster than others, plus temperature has a huge impact (rule of thumb is that the rate of reaction doubles for every 10 degrees increase in temp).
but essentially until it's hardened and doesn't zap.
but essentially until it's hardened and doesn't zap.
Captain soapman
New Member
Whats the longest amount of time it can take the soap to stop zapping. Can it take up to six weeks or longer.
question number two i went to pour my cold process it began to sieze up on me. My lye was to hot. But the wierd thing when i poured it it was like shifting to apple sauce but the bar actually turned out. Did i get lucky its been a few days and i still get zapped. Im hoping it will still dull down. Any thoughts?
question number two i went to pour my cold process it began to sieze up on me. My lye was to hot. But the wierd thing when i poured it it was like shifting to apple sauce but the bar actually turned out. Did i get lucky its been a few days and i still get zapped. Im hoping it will still dull down. Any thoughts?
The answers already given are reasonable. In general, CP soap should generally be zap free within a day or two if you're using a recipe that is calculated correctly, your scale is working correctly, you're measuring accurately.
If there is some problem with how the soap was made, then yes the soap can stay zappy longer than that. A small excess of alkali may dissipate with time, but if there is enough excess alkali, the soap can stay permanently zappy. In either case, you need to figure out why that particular batch is not right.
This thread is over 10 years old, and it's about active lye, not about seizing. You need to ask your other question in a new thread so more people will see it and you'll get more advice.
If there is some problem with how the soap was made, then yes the soap can stay zappy longer than that. A small excess of alkali may dissipate with time, but if there is enough excess alkali, the soap can stay permanently zappy. In either case, you need to figure out why that particular batch is not right.
This thread is over 10 years old, and it's about active lye, not about seizing. You need to ask your other question in a new thread so more people will see it and you'll get more advice.
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