What is your lye mixing container made out of?

I've been using stainless steel that say that on the bottom of the pots, never anything less. But lately I've noticed when I scrape the last of the lye water out of it there's a little tich of grey. Like some of the metal is coming off. Not enough to affect the color of the soap or anything but it kind of bothers me.

I know you can't use glass, even if the heavy thick kind so what else is there to mix lye and water in?

I use heat resistant pyrex and haven't had any problems. Should I not be using that?

I've used the Pyrex but then switched to a stainless steel bowl after reading that the Pyrex could break.

I didn't know there was heat-proof Pyrex available. I'm not sure but I don't see how that could break. Unless the combo of lye and heat together would cause that.

there are a few discussion of it.
- Pyrex isn't as stable as it used to be (chemically different)
- small scratches compromise the strength of the glass
- lye etches the glass (see above)

Use stainless (watch the quality of the stainless!) or plastic. Some use rubbermaid pitchers (with lids), I use those tall gladware containers with lids, oh and nalgene is also supposed to be a good choice.

I have been using Pyrex, but it holds the heat for so long. I have tried plastic, it is a little cloudy now, but it isn't like the lye stays in there for long.

Pyrex is a bad idea for the reasons that carebear mentioned.

And it's not just breakage. I've read descriptions of explosive shattering (with no warning and no obvious weakness or cracking to the glass). Think shards flying everywhere. I don't know how often that happens but do you really want to take the risk?

Plastic pitchers....

I do assembly line production though, and often do 4-8 batches in one sitting. So I'll have the water measured out, with the dry NAOH next to it in a sealed little plastic container (think snap lock or take n toss). Just before I start one batch I mix the lye for the next...then it has time to cool. Its kept away from me on a separate table so no chance of me knocking it over. Then after I mold the batch I'm working on I toss everything into the "wash" tub and mix up the next lye, then start the second batch...and repeat.

And yes...I have a LOT of bowls, spoons, pitchers, scrapers, and molds.

I use a plastic container that the lye cam in, it has a really wide mouth so its easy to pour into and out of, I also use plastic icecream containers

PP#5 (polypropylene) Rubbermaid pitcher.

I mix and store mine in a laundry detergent bottle.
The bottom has HDPE printed on it (High Density Polyethylene)

Ditto on keeping your lye away from glass. In the past, household Pyrex used to be made with stable/strong borosilicate, but not any longer, and many people are reporting that they have been having shattering/explosive experiences with it. So much so that the Dept for Consumer Affairs has been investigating it, and even Consumer Reports did their own experimental studies which confirmed the shattering problems.

Here is an excellent article by NACE (the National Association of Corrosion Engineers) that explains how alkiline solutions attack glass over time:
http://events.nace.org/library/corrosio ... /Glass.asp

The problem with mixing lye solution in glass is that the corrossion happens slowly over time, bit by bit, so it's easy to get lulled into a sense of security when we continue to mix lye solution in the glass seemingly without incident. But every time you mix solution in the container, the glass gets weaker and weaker until one day out of the blue- Kaboom!- dangerously sharp shards of caustic lye soaked glass everywhere. You won't know the day or hour beforehand that it will happen because the gradual weakening is not something you can see happening without a microscope, but it is happening. I liken soaping with glass to playing Russian Roulette. It's just not worth the risk, especially when there are much safer alternatives out there.

I've posted this many times before, but here are the safe alternatives:

For mixing lye solution, it's best/safest to use plastic or quality stainless steel. Not just any plastic will do, though. The best plastic container to use for mixing lye solution is PP #5 because it is resistant to lye and can withstand boiling water.

HDPE #2 is good for long-term storage of cooled lye solution, but not as ideal as PP #5 for mixing solution because it has a lower temp threshold than pp #5.

Never use these plastics: polycarbonate (the crystal clear Rubbermaid containers); nylon (polyamide); polystyrene plastics (PS #6, or ABS which is a type of styrene plastic- acrylonitrile butadiene styrene); and PETE (#1). None of these are compatable with lye.

Acrylics are ok for very short term exposure, but not for repeated use or long term storage.

Oh, and as carebear mentioned, nalgene is good, too, from what I've read.

Here is a recent thread (from last month) where this subject was discussed (just scroll down a little).

http://www.soapmakingforum.com/forum/vi ... r&start=15


IrishLass


Edited to add: I mix my masterbatch 50% lye solution in PP #5, and I store it longterm in HDPE.

I use borosilicate (while being aware that any glass can possibly break).

Regarding the grey residue, I noticed that my stainless pots are much cleaner after I dissolve the lye

Or to put it differently: it may be plain dirt ...

You probably would notice any corrosion through careful examination of your pot.

I use a plastic bucket which was purchased specifically for the purpose of mixing my lye. I don't store it in there as I mix it up fresh each time I make soap.

Fragola said:

I use borosilicate (while being aware that any glass can possibly break).

Click to expand...

This is not the Pyrex available in the US. So please if you choose to promote its use be sure to differentiate. Also be aware that the integrity of your borosilicate is seriously compromised if it is scratched or bumped. Which, IMO, makes it a poor choice if other options are available.

We don't recommend using any form of glass for lye.

Wow I'm glad I found this thread. I have been using pyrex and had no clue about the risks. Thankfully I have a measuring jug that looks like a PP#5 in the cupboard. The 5 is in the centre of a recycled sign and the PP is underneath - it may be an obvious question but I want to be sure before I start using it - is this correct for PP#5 plastic?

thick, sturdy plastic chinese take-out container

erniemay said:

Wow I'm glad I found this thread. I have been using pyrex and had no clue about the risks. Thankfully I have a measuring jug that looks like a PP#5 in the cupboard. The 5 is in the centre of a recycled sign and the PP is underneath - it may be an obvious question but I want to be sure before I start using it - is this correct for PP#5 plastic?

Click to expand...

Yes.

IrishLass said:

For mixing lye solution, it's best/safest to use plastic or quality stainless steel. Not just any plastic will do, though. The best plastic container to use for mixing lye solution is PP #5 because it is resistant to lye and can withstand boiling water.

HDPE #2 is good for long-term storage of cooled lye solution, but not as ideal as PP #5 for mixing solution because it has a lower temp threshold than pp #5.

Never use these plastics: polycarbonate (the crystal clear Rubbermaid containers); nylon (polyamide); polystyrene plastics (PS #6, or ABS which is a type of styrene plastic- acrylonitrile butadiene styrene); and PETE (#1). None of these are compatable with lye.

Acrylics are ok for very short term exposure, but not for repeated use or long term storage.

Oh, and as carebear mentioned, nalgene is good, too, from what I've read.

Here is a recent thread (from last month) where this subject was discussed (just scroll down a little).

http://www.soapmakingforum.com/forum/vi ... r&start=15


IrishLass


Edited to add: I mix my masterbatch 50% lye solution in PP #5, and I store it longterm in HDPE.

Click to expand...

Like BluebirdMama, I also use a PP# 5 Rubbermaid pitcher but sometimes I use a stainless steel pot if I'm making a smaller than usual batch.

I use a small stainless steel carafe that I ordered from a science lab supplier. It was quite expensive but I have never had a problem since I started using it. It is a very high quality ss. By the way, our pyrex is all made in China now and that is one reason that it is of such poor quality.

Previously I've used a Rubbermaid pitcher for mixing the water/lye. Recently, I started using the quart container that soup came in from Chinese takeout. It is PP5. The pitcher was just too big for my needs since I usually soap 2lbs. oil at a time.