reheating lye

Susie said:

I would let the oils be a bit warmer rather than trying to heat the lye solution. Or, as I stated earlier, don't masterbatch and just use fresh hot/warm lye solution. [...]

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Well, yes, but aren't the oil and lye supposed to be within the same temperature range? Do you mean that if my lye is at room temperature I can just heat my oils up and that would make up for the temperature change I need?

As for the masterbatch, I like to masterbatch rather than have to handle the raw lye every time I soap and usually I can be sure it is further dissolved when I leave it standing in water. I may rethink this since this false trace issue has come up now. Mixing by hand never gave me significant false trace problems, even with the lye water at room temp. At least I could beat it out without it separating into water at the bottom and thick soap mix at the top.

Every other point is well noted, thanks.

ycartf said:

I rewarm lye mix all the time in the microwave. I heat 32 oz of water/lye on high for about 2.5 minutes to get it to about 120 degrees.

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Thanks. Good to know. I've never done that, tho. But my batches are a lot smaller. I feel safe nuking at #3 (Defrost) for a few seconds. Not sure I'd go to high. Scary! LOL

ycartf said:

I have never had a problem with my Pyrex-like batter bowl (another brand) and I have mixed AND reheated in it over 40 times. I don't know if folks who have them shatter have caused/allowed sudden temperature changes like immersing in a sink of ice water while the lye mix was near boiling or what.

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Ditto. I've wondered that as well... or setting the Pyrex on a cold surface straight out of the microwave. I have a wooden chopping board near the microwave and another one next to the kitchen sink. Maybe that's why I've never had the problem??? Dunno.

ycartf said:

I tried plastic before and it appeared to take on a color as though it had dissolved a little of the plastic into the mix.

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Exactly! Me too. I always worried about that... then it happened recently with a highly recommended #2 plastic container -- it melted and the lye turned milky white from the white plastic container. Ugh.

I'll stick with Pyrex, thank you very much. I just feel safer using it. But that's just me and I think everyone should feel free to decide for themselves.

Vetivier said:

NEVER EVER reheat lye solution in a microwave. Too dangerous, fumes, splatter, explosions, Chemical burns.
dont even think about stovetop
Warm water bath and patience.

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Hi, this quote pretty much sums it up for me

Many years ago, I used a glass mason jar to mix my lye solution and never had an issue. The etching was something I didn't know about and quickly stopped when I read about it on this very forum.

There's no reason to take a chance with glass. Just don't. And if you're masterbatching, just add your additional water to the lye solution and it will get quite hot (enough to make you wait forever, and say to yourself, 'I could've just made a single batch of lye solution like the old days'). I add the water to my oils and the room temp lye solution when I'm ready.

AngelBar said:

And if you're masterbatching, just add your additional water to the lye solution and it will get quite hot (enough to make you wait forever, and say to yourself, 'I could've just made a single batch of lye solution like the old days'). I add the water to my oils and the room temp lye solution when I'm ready.

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Oh, really? Just water to the room temp lye solution to get it hot again? Kindly clarify. The last sentence is really confusing things for me because you mention oil there.:think:

Soaps House said:

A lot of people think that lye is something a bit more dangerous than it really is. ... Shoot, I'd like to put some frozen lye into the microwave tomorrow just to see, because you never know if you don't try.

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Um, too risky for me, but I hafta say, "Experience is the best teacher!"

xyxoxy said:

Lye isn't dangerous at all...Soapmakers who don't have the necessary knowledge and respect for lye are what is dangerous. Children and pets running around where lye is just minding it's own business are also dangerous.

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"Minding its own business" indeed. Well said.

IrishLass said:

Re: reheating lye. I do it all the time, but not in the microwave. I just fill up a small pan with hot water and stick my lye solution container into it, changing out the cooled-off water for more hot water as needed until my lye solution has warmed up enough.

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MissE said:

Well, yes, but aren't the oil and lye supposed to be within the same temperature range? Do you mean that if my lye is at room temperature I can just heat my oils up and that would make up for the temperature change I need?

As for the masterbatch, I like to masterbatch rather than have to handle the raw lye every time I soap and usually I can be sure it is further dissolved when I leave it standing in water. I may rethink this since this false trace issue has come up now. Mixing by hand never gave me significant false trace problems, even with the lye water at room temp. At least I could beat it out without it separating into water at the bottom and thick soap mix at the top.

Every other point is well noted, thanks.

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Your lye and oils do not need to be the same temperature. I am not sure why everyone thinks so, but no. Your oils can be hot, your lye cool, or vice versa. The only thing that matters is if you are swirling, you need to soap cooler than if you are not.

MissE said:

Oh, really? Just water to the room temp lye solution to get it hot again?...

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Yes, this will happen. If you make an NaOH solution, let it cool to say room temperature, and then add more water to this solution, it will warm up again. Not as hot as when you made the original solution, but it will heat up.

The chart below shows the temperature rise that you will see if you add various amounts of 70 F (20 C) water to a 50% NaOH solution that starts at various temperatures. The bottom curve is what you will see if your NaOH solution starts at 80 F (25 C). If you add sufficient 70 F (20 C) water to dilute the NaOH solution to 30% NaOH, the temperature of the mixture will rise from 80 F (25 C) to roughly 135 F (57 C).

"... And if you're masterbatching, just add your additional water to the lye solution and it will get quite hot.... I add the water to my oils and the room temp lye solution when I'm ready. ..."

Either way you do it, when you add water to an NaOH solution, the process will release heat.

You are less likely to notice the heating when you add the water to the oils and then add the lye solution, but the same amount of energy is released by the process of diluting the NaOH.

If it makes you more comfortable to add the water to the oils and then add the concentrated NaOH solution, by all means do so. But you will end up in pretty much the same place as if you add the water to the NaOH solution and then pour that into the oils without waiting for the lye solution to cool.

MissE said:

Oh, really? Just water to the room temp lye solution to get it hot again? Kindly clarify. The last sentence is really confusing things for me because you mention oil there.:think:

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Sure MissE, hi!

I stopped caring about temps a while ago. Master-Batching is a 50/50 (any percent offset), Lye to Water solution. You will do this usually in larger quantities and use the solution over time. The MB will be cooled to room temp before placing into the proper HDPE #2 bottles.

When making a Soap recipe with a 50/50 solution, you will need to calculate the amount of water to offset the difference. If you put the offset into the mixture, it will heat up again. To avoid this, I put this offset into the oils before the lye solution. It doesn't matter which way you do it, the process will create a lot of heat. It seems to be delayed a bit when I put it in the oils first. It also seems to gel better for me.

Susie said:

Your lye and oils do not need to be the same temperature. I am not sure why everyone thinks so, but no. Your oils can be hot, your lye cool, or vice versa. The only thing that matters is if you are swirling, you need to soap cooler than if you are not.

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Hi Susie, from what I understand reading countless online articles (AKA Online Diploma in Soap Education. . . ah, the hours! ) oils congeal when they hit cold lye water, especially hard oils which are solid at room temperature, causing a false trace.

Funnily enough, though, when I tried to warm oil and lye solution up, I still hit false trace regardless.

I'm now not sure what is what and what to do.

Thanks again.

DeeAnna said:

Yes, this will happen. If you make an NaOH solution, let it cool to say room temperature, and then add more water to this solution, it will warm up again. Not as hot as when you made the original solution, but it will heat up[...]

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You know, the science of soapmaking never ceases to amaze me, like I'm 'dabbling' in science for real?

Thanks so much for the tips, DeeAnna, it's so much clearer now and I am certainly going to use the {(oil+water) + lye solution} tip next time.

But, if I don't allow things cool down a bit, won't that cause my soap to heat up excessively and, I don't know, crack or do whatever nasty thing soap does when it has heated up too much?

Thanks again!

AngelBar said:

Sure MissE, hi!

I stopped caring about temps a while ago. Master-Batching is a 50/50 (any percent offset), Lye to Water solution. You will do this usually in larger quantities and use the solution over time. The MB will be cooled to room temp before placing into the proper HDPE #2 bottles.

When making a Soap recipe with a 50/50 solution, you will need to calculate the amount of water to offset the difference. If you put the offset into the mixture, it will heat up again. To avoid this, I put this offset into the oils before the lye solution. It doesn't matter which way you do it, the process will create a lot of heat. It seems to be delayed a bit when I put it in the oils first. It also seems to gel better for me.

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I actually do a 100% master batch. Like I said, I use the same recipe over and over and so doing this, I can just take the quantity I want and go. But if I am going to continue to masterbatch and also still need to soap at slightly higher temperatures, a 50/50 solution is a good starting place. Yes, adding water to heat things up is so neat it just seems planning ahead for it by doing a 50-50 solution is the ONLY thing to do.

I really would prefer to continue to do my room temperatures ultimately, but for now I have to figure out false trace issues hence the troubleshooting with higher temperatures.

Much love for weighing in, AngelBar.

Zany_in_CO said:

I'll stick with Pyrex, thank you very much. I just feel safer using it. But that's just me and I think everyone should feel free to decide for themselves.

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I like my stainless steel lye pot. If, for some reason I ever decide that I really MUST heat a lye solution, the pot can be set straight on the stove on low. Or in a water bath. If I drop my lye pot, it bounces. Of course, if it's full it splashes and bounces, but then I "only" have the problem of spilled lye to cope with, it isn't compounded by broken glass everywhere.

Kittish said:

I like my stainless steel lye pot. If, for some reason I ever decide that I really MUST heat a lye solution, the pot can be set straight on the stove on low. Or in a water bath. If I drop my lye pot, it bounces. Of course, if it's full it splashes and bounces, but then I "only" have the problem of spilled lye to cope with, it isn't compounded by broken glass everywhere.

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Oh, I have one of those! That's probably what I should have used yesterday when my batch was misbehaving and I was wishing I could cook my soap up to save it!