When using a 50 lye/50 water masterbatch solution, can you add the recipe's remaining water into the oils (as opposed to the solution) to prevent the lye/water solution from heating up? Or is it better to pour the recipe's remaining water into the solution?
When using a 50 lye/50 water masterbatch solution...
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boyago
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Yes, I also don't think that adding more water to the solution would heat it up anymore as the NaOH has already... sorry brain is failing, I think that it has already changed phase?... broken it's bonds with itself to make the solution and at 50/50 it cant get any more... solutiony.
(boyago suddenly realizes he needs to spend less time on SMF and more at Khan Academy) somebody who know better slap me and step up.
Strictly from personal experience I add my water or alternative liquid to the oils separate from the lye all the time and haven't had a problem.
(boyago suddenly realizes he needs to spend less time on SMF and more at Khan Academy) somebody who know better slap me and step up.
Strictly from personal experience I add my water or alternative liquid to the oils separate from the lye all the time and haven't had a problem.
Thank you so much for taking the time to reply!
girlishcharm2004
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The lye will heat up again, but only slightly. Also, it is perfectly fine to add the addition water straight to the oils. 
Yes- what the others have said- you can add the extra water directly to the oils instead if you choose.
Also- ditto what GirlishCharm said about the lye solution heating up again, but only slightly when adding the extra water to it.
IrishLass
Also- ditto what GirlishCharm said about the lye solution heating up again, but only slightly when adding the extra water to it.
IrishLass
Yes, the water does heat up again, so that can be a good way to purposefully warm it up if you need to (e.g., when I leave my solution outside my patio door too long during winter).
Soap Techniques
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I'm curious, what is the chemistry behind this reaction? Why would adding more water to the cooled lye solution heat it up again?
girlishcharm2004
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I will try to explain this to the best of my limited knowledge. When water mixes with lye, it separates the lye into ions Na+ and OH-. It will continue to react (and produce heat) when more water is added until all the NaOH has separated into it's respective ions.
Yep, exactly what GirlishCharm said.
In a 50:50 solution, the NaOH is dissolved into solution BUT not all of that NaOH has dissociated (broken up) into its ionic Na+ and OH- parts. Some of it is still in its molecular form (NaOH).
When you add more water, the process of NaOH dissociation will cause a release of more heat energy -- you can't avoid that. But what you can control is the rise in temperature in response to the released heat.
When you add the extra water to the oils and then add the lye solution, you are "diluting" the heat energy because there's a larger amount of stuff to heat up. That means the temperature rise won't be as large as when you add the extra water to just the lye solution. But don't be misled -- the energy release is still happening.
For the chemists and engineers and just plain curious geeks, the two types of heat release involved in this example are heat of solution and heat of dissociation.
In a 50:50 solution, the NaOH is dissolved into solution BUT not all of that NaOH has dissociated (broken up) into its ionic Na+ and OH- parts. Some of it is still in its molecular form (NaOH).
When you add more water, the process of NaOH dissociation will cause a release of more heat energy -- you can't avoid that. But what you can control is the rise in temperature in response to the released heat.
When you add the extra water to the oils and then add the lye solution, you are "diluting" the heat energy because there's a larger amount of stuff to heat up. That means the temperature rise won't be as large as when you add the extra water to just the lye solution. But don't be misled -- the energy release is still happening.
For the chemists and engineers and just plain curious geeks, the two types of heat release involved in this example are heat of solution and heat of dissociation.
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Soap Techniques
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GirlishCharm, DeeAnna, thank you so much for the explanation! It really puzzled me...
