# What is your lye mixing container made out of?



## Maythorn (Jan 15, 2012)

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?


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## ghia61 (Jan 15, 2012)

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


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## TuxedoKat (Jan 15, 2012)

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


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## Maythorn (Jan 15, 2012)

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.


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## carebear (Jan 15, 2012)

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.


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## Soapy Gurl (Jan 15, 2012)

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.


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## judymoody (Jan 15, 2012)

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?


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## Tegan (Jan 15, 2012)

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.


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## Traceyann (Jan 15, 2012)

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


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## BluebirdMama (Jan 15, 2012)

PP#5 (polypropylene) Rubbermaid pitcher.


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## xyxoxy (Jan 16, 2012)

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


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## IrishLass (Jan 16, 2012)

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.


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## Fragola (Jan 16, 2012)

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.


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## Bubbly Buddha (Jan 16, 2012)

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.


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## carebear (Jan 16, 2012)

Fragola said:
			
		

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


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.


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## erniemay (Jan 16, 2012)

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?


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## paillo (Jan 16, 2012)

thick, sturdy plastic chinese take-out container


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## Hazel (Jan 16, 2012)

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?



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.
> 
> ...



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.


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## reallyrita (Jan 16, 2012)

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.


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## kharmon320 (Jan 16, 2012)

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.


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## dcornett (Jan 17, 2012)

I've always used a rubbermade pitcher with no problems (except it could be smaller LOL)


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## eleraine (Jan 17, 2012)

PP# 5 here - it's a 1 liter measuring pitcher.


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## ghia61 (Jan 17, 2012)

Would lye/water solution react with silicone? I see many people use silicone molds. Thanks


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## Maythorn (Jan 17, 2012)

I never thought of using plastic because I thought it would melt or warp but I use a heatproof spatula to stir my soap.  Must be made of the same type of thing.

By the way, thanks for all your information given here.  I'm going to check out that Rubbermaid pitcher.  

Does everyone scrape the lye water out of the pot or container?  I do this to get all of it.  Not real fun though.


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## carebear (Jan 17, 2012)

i don't.


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## PrairieCraft (Jan 17, 2012)

I don't scrape my rubbermaid lye pitcher out either.  There's a potential for spattering the stuff on yourself doing that.


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## ElkRiverSoapCo (Jan 17, 2012)

stainless steel


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## BakingNana (Jan 18, 2012)

One thing to add.  

Some of the older books (maybe even newer ones - who knows?) out there have glass bottles or containers recommended for mixing lye.  If you are loaning out books or giving one, you'll want to check on this and make the correction before passing it on.


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## Cuckoo Bananas (Mar 10, 2012)

What's the issues regarding the quality of stainless steel? I was planning on making a bigger soap batch this time and was going to use a jumbo stainless steel pot that I got from a cheapo store as my mixing pot (I've used it before for mixing soap).....and so I was thinking about using my usual stainless steel mixing pot as my big lye mixer this time.

I'm sure the quality of stainless steel wouldn't be that great but if it's been fine for mixing soap for a couple of years I imagine it would be fine for mixing the lye water???? Pipe up if anyone knows any dangers of this...


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## AmyW (Mar 10, 2012)

I recycled a plastic coffee (folgers) can; the new ones have a nifty handle and it's tall and straight sided enough that it directs the fumes up into the stove vent.


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## ElkRiverSoapCo (Mar 10, 2012)

Stainless steel is safe to use. You need to watch for the other ones like aluminum. Those are no good!


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## carebear (Mar 10, 2012)

AmyW said:
			
		

> I recycled a plastic coffee (folgers) can; the new ones have a nifty handle and it's tall and straight sided enough that it directs the fumes up into the stove vent.



Just be careful about the stove vent - the "filters" are often aluminum and the fumes are caustic, so with enough exposure...


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## Sanguine (Mar 10, 2012)

I've been using a tupperware jar that seems to be able to take some heat, not sure if it's good for it though...


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## maya (Mar 10, 2012)

i use a restaurant lidded bucket that is number 5 plastic.


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## fiddletree (Mar 11, 2012)

I use a stainless steel pitcher/pot thing. It's great!


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## dirrdee (Mar 11, 2012)

regarding Pryex, I would NOT use it ever for lye.  Couple years ago, my DIL put a wet pryex dish on top of a warm burner on the stove (at Thanksgiving) and it EXPLODED, seriously, it was awful and glass got into all of our prepared food, and we had to throw it out.  I cant imagine the castastrophe of having burns all over from that...dont do it!

Sorry, that was my mom lecture...I use a stainless pan, and also it cools much faster in an ice bath than glass or ceramic.


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## AmyW (Mar 11, 2012)

carebear said:
			
		

> AmyW said:
> 
> 
> 
> ...



Yep, I knew I was leaving something out of my post! They get changed regularly, and I'll have a soaping room soon and will use fans to direct it out the window then. The windows in my inlaw's kitchen are higher up and with the way the kitchen is set up, I don't have a good way to direct a fan.

Can't wait for our own house...


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## Maythorn (Mar 11, 2012)

dirrdee said:
			
		

> regarding Pryex, I would NOT use it ever for lye.  Couple years ago, my DIL put a wet pryex dish on top of a warm burner on the stove (at Thanksgiving) and it EXPLODED, seriously, it was awful and glass got into all of our prepared food, and we had to throw it out.  I cant imagine the castastrophe of having burns all over from that...dont do it!
> 
> Sorry, that was my mom lecture...I use a stainless pan, and also it cools much faster in an ice bath than glass or ceramic.



How awful.  There went that meal it sounds like.  I used a pyrex cup for mixing lye when I first started out and now I shudder to think about it.  Very small batches but still.


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## green soap (Mar 11, 2012)

Wow!  this is terrible to lose your thanksgiving meal!  

DH gifted me a nestling set of 3 flexible silicone 'beakers' for that purpose. You could call them measuring cups, but the shape is more like a beaker. I use the quart sized one.  I make pretty small batches, but I like the deep walls, just in case the lye gets mad at anything pre-existing in that silicone beaker.  You know, honey in the water, goat milk, weird teas....so far so good.  The walls of the 'beaker' appear to have zero reaction to the lye, unlike some tupperware stuff i was using previously.  I really like them for lye, and for the ocasional swirl I do (transfer batter and color), and they are reserved for these purposes.  Also, I have been immersing the whole thing in a pot (SS) of cold water, and the lye cools pretty fast.

Before that wonderful gadget, and before the tupperware, I was using pyrex.  I stopped as soon as I read this thread.  Did I ever tell you nice folks how much I appreciate the information sharing in this forum?  

I had an empty pyrex measuring cup shatter when I dropped it on a not very hard surface.  I had been using it to measure the dry lye.  This alerted me to the pyrex issue right away.  I am now using SS to measure the lye.  What does everybody else use?


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## scrubbie (Mar 11, 2012)

This is mine. These are chemical resistant and can be autoclaved which means 274 degrees at 30 psi, if I remember rightly from my dental days. I spoke to company myself. At 5.25 I got 3 
http://secure.sciencecompany.com/Plasti ... -C644.aspx

My size 
http://secure.sciencecompany.com/Plasti ... 1C644.aspx

I got my chem aprons here and my safety gear.
Yuppers: here are auto clave temps and times. So these pitchers 
 are good. I like them a little tall.
http://www.sterilizers.com/autoclave-ti ... chart.html


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## dirrdee (Mar 11, 2012)

It was a major bummer, and we did throw out most of the food but at least no one was injured... My poor DIL felt terrible, but very important lesson learned for everyone!

Just think if there was lye in it?  Dont do it please!


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## CamillaHB (Mar 12, 2012)

carebear said:
			
		

> Just be careful about the stove vent - the "filters" are often aluminum and the fumes are caustic, so with enough exposure...


I was wondering about that one. Good to know. Thanks!

On the other hand, I think mine has a nice, thick protective layer of grease


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## Seventeen Soaps (Mar 13, 2012)

Wonderful insight thank you!   I have been using the same Pyrex jug since I started making soap which makes it 13 yrs old.  I only use it now for my smaller trial batches and had no idea they were a heat danger... looks like I will need a new jug although mine clearly states microwave safe :/      For my larger batches I use either a plastic jug or a large plastic container.


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## carebear (Mar 13, 2012)

microwave safe is not relevant.  it's not just about the heat.
pyrex just isn't safe for a lye solution.  period.

i'm glad you will get a new container.  even tho it's worked for you thus far, it might shatter tomorrow.  in the risk vs reward calculation, finding a new jug isn't much.


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## carebear (Mar 13, 2012)

CamillaHB said:
			
		

> On the other hand, I think mine has a nice, thick protective layer of grease


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## Guest (Mar 13, 2012)

Is it safe to mix lye in glass? Yes, it is, but there are a boatload of caveats and limitations that go along with that. A lot of the complaints of exploding Pyrex are the result of misuse of the glassware. Pyrex in any form is not indestructible, and most people don't read the safety warnings that come with their measuring cup. There are some things that you simply should not do to Pyrex, like cooling it rapidly. But to add to that problem, Pyrex is a brand, not a material, and the materials used to make Pyrex differ.

The Pyrex kitchenware brand was divested by Corning to World Kitchen back in 1998. Up until that time, Corning was producing it's Pyrex branded kitchenware out of both borosilicate and tempered soda lime glass. Two different materials with two different set of properties. 

http://www.udel.edu/chem/GlassShop/PhysicalProperties.htm

Since World Kitchen took over production of Pyrex branded consumer products, all Pyrex kitchenware is made with tempered soda lime glass. It is possible that the Pyrex measuring cup that you bought in 1975 is soda lime glass, too. Whether World Kitchen's manufacturing standards are the same as Corning's were, well, we don't know.

Corning continues to make Pyrex labware from borosilicate.

IMHO, when manufactured correctly, and when used properly (including throwing it out when it becomes scratched or otherwise compromised), both are safe for mixing lye. When I worked in a lab, we mixed strongly alkaline solutions in Pyrex labware all the time, without incident. I have used soda lime for mixing lye for many years, no problem.
(Glass of any kind is NOT suitable for the long-term storage of alkaline solutions.)

But that is a lot of "ifs" to contend with. When there are much more reliable materials, like SS and appropriate plastics, available for mixing and storing lye, why not use them?

There are two possibilities that I see for why we are hearing a lot of complaints about exploding Pyrex kitchenware. First, the rise in complaints mirrors the rise of the internet, so, whether they are justified or not, we all hear about problems with Pyrex. Second, there might be a real problem with the "new" Pyrex kitchenware. Or, it's a combination of the two. I will end by saying that the CPSC has not found fault with World Kitchen's products. I'm not sure what that means, as the CPSC is a political agency, and works in the best interest of the government, not the consumer. And I doubt that the CPSC tests Pyrex for safety in mixing lye.

Here are a couple of good online references for Pyrex, both the kitchen stuff and labware:

Wikipedia on Pyrex: Seems mostly accurate
http://en.wikipedia.org/wiki/Pyrex

Anchor-Hocking Q&A on their soda lime glass products
http://www.anchorhocking.com/Bakeware_Facts.html

Snopes runs down the soda lime/borosilicate controversy
http://www.snopes.com/food/warnings/pyrex.asp

Corning's borosilicate Pyrex lab glass safety info:
http://catalog2.corning.com/lifesciences/media/pdf/glass_care_safe_handling_RG_CI_101_REV1.pdf


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## carebear (Mar 13, 2012)

No, it is not safe to mix lye in glass.  Pyrex or otherwise.  Those "caveats" are the reality and not the exception.  

Don't do it.  Don't say it's safe.  It isn't.


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## agriffin (Mar 13, 2012)

carebear said:
			
		

> No, it is not safe to mix lye in glass.  Pyrex or otherwise.  Those "caveats" are the reality and not the exception.
> 
> Don't do it.  Don't say it's safe.  It isn't.



I absolutely agree with this.


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## Guest (Mar 13, 2012)

"Safe" is a relative term. To make a blanket statement that Pyrex is not safe for mixing lye is incorrect. Pyrex borosilicate is absolutely safe for mixing lye, within the limits of the material's abilities. Pyrex soda lime glass is also safe, but it is more prone to etching from alkali than it's borosilicate cousin. Etched glass should never be used. 

All materials have their limitations, and if you work within those limitations, the chances of failure are greatly minimized. Know the materials that you are working with.

Are there better choices than glass (of any kind) for mixing caustics? Yes, you bet there are, and I said so, very clearly. Stainless steel or an appropriate plastic are much better, and safer choices for mixing lye.

There are a lot of dangers in the world, and we should be aware of them, but not ignorant of them.


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## carebear (Mar 13, 2012)

carebear said:
			
		

> No, it is not safe to mix lye in glass.  Pyrex or otherwise.  Those "caveats" are the reality and not the exception.
> 
> Don't do it.  Don't say it's safe.  It isn't.


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## debbism (Mar 13, 2012)

carebear said:
			
		

> Just be careful about the stove vent - the "filters" are often aluminum and the fumes are caustic, so with enough exposure...



THIS!!  I remove these for soap making.  Mine pop out easily.


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## Guest (Mar 13, 2012)

debbism said:
			
		

> carebear said:
> 
> 
> 
> ...



Good advice. Take a look at an old chem lab and you'll see that the fixtures are corroded. If you can, measure NaOH and mix lye outdoors, let it react and dissolve before bringing it inside.


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## Genny (Mar 13, 2012)

woodsroad said:
			
		

> There are a lot of dangers in the world, and we should be aware of them, but not ignorant of them.



But the problem with saying that it can be safe on a forum is that a newbie to cp will see it, not read any further because they got the info they were looking for, and then use the glass.
Do we want to be partialy responsible for someone getting seriously injured?  Not really.


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## Hazel (Mar 13, 2012)

"Safe" is _*not *_a relative term. Either it is safe or it isn't. There isn't an in between or maybe about being safe. 

I don't understand why you keep pushing this "Pyrex is safe issue" when you know there are safe alternatives. Even after people have posted about Pyrex shattering and exploding, you still talk about being aware of dangers and not ignorant of them. Have you even read current and older posts by members who have experienced Pyrex shattering and have warned people not to use it?

Why would you even take the risk? In my opinion, to know there is even a minute possibilty of Pyrex shattering and still use it is ignorant.

Genny brought up a very good point. We don't want a person new to soapmaking to think it's all right to use glass/Pyrex and possibly get injured. 

I'm ending this post by quoting SMF's Site Admin because I'm tired of people's careless attitude towards safety.



			
				SMF said:
			
		

> The SMF's definition of an internet troll:
> 
> "In Internet slang, a troll is someone who posts controversial, inflammatory, irrelevant or off-topic messages in an online community, such as an online discussion forum or chat room, with the primary intent of provoking other users into an emotional response or to generally disrupting normal discussion."-WIKI
> 
> ...


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## IrishLass (Mar 13, 2012)

Woodsroad- please remember the audience to which you are addressing here. _We are handmade soapmakers working out of our limited budgets in our home kitchens_-  not  grad students or professional chemists working in chemistry labs with access to certified (and paid for) lab equipment. 

To recommend that glass is relatively safe for mixing lye solution is the same to me as saying playing Russian Roulette is relatively safe........yeah, it's relatively safe for a certain amount clicks of the trigger, but once the chamber with the bullet in it finally comes 'round, it's not so safe anymore, is it?  It's the same with glass and lye. Strong alkaline solutions etch glass over time- even borosilicate. Sure, it's safe for a certain amount of lye solution batches, but how many? Do you know? And if so, are you willing to guarantee that? I'm sure the answer to those questions is no. Too many soapers I know have reported their tempered glass containers (either Pyrex or Anchor-Hocking) shattering and sending shards of glass and lye solution all over their kitchens and persons after having used it 'relatively safely' without incident for a time. Our #1 concern is safe soaping here and we feel it would be negligent on our part to advocate or promote the use of a product that has proven dangerously unreliable. I hope you can see our point of view and understand why we are very firm on our stance.  

Here are two excellent links to read:

http://events.nace.org/library/corrosio ... /Glass.asp


http://www.consumerreports.org/cro/maga ... /index.htm


IrishLass


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## Guest (Mar 13, 2012)

IrishLass said:
			
		

> Here are two excellent links to read:
> 
> http://events.nace.org/library/corrosio ... /Glass.asp
> 
> ...



Very good information, thank you!


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## Kleine Teufel (Mar 14, 2012)

I've been using the same glass wine bottle (open mouth) for over two years for mixing my lye. I've been doing it out of sheer laziness and basically arrogance (it won't happen to me kind of mind-frame). I finally, finally bought several 2qt bottles (wide mouth of course) of tea (forget the brand name) so that I can demolish the tea (we drink a lot of tea) and use the plastic containers to mix the lye. Not only will I now have a safer means of mixing my lye, but I'll also have SIX containers to mix lye in, instead of one. I'm stoked!

ETA: I'm absolutely not condoning glassware use for lye. Just adding my two cents as to how much of an idiot I am. At any point in time that glass could have been bumped and shattered everywhere. With the heat extremes and etching of the glass, I'm just about positive it would have happened at some point in time and it's basically sheer luck that it hadn't happened already.

*Is it bad that soaping is so addictive that you make beverage choices based on container suitability to lye?!*


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## busymakinsoap! (Mar 15, 2012)

I have had a pyrex jug explode, luckly I wasnt mixing lye, but melting oils in a double burner.
The jug didnt just crack or break, it does actually explodes, like everywhere. I was finding glass for days and contaminated all of my product.  Imagine the damage if lye were involved.


I use stainless steel for my lye mix.


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## Hazel (Mar 15, 2012)

Thanks for sharing, ladies!

busymakinsoap - 

You were still lucky you weren't hurt. If the oils had been hot, you could have gotten some bad burns.


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## wendenney (Mar 15, 2012)

I chose to use an old coffee carafe I had from a coffeemaker I no longer use figuring they were made to withstand hot temperatures for sitting on a hot plate for hours on end.


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## IrishLass (Mar 15, 2012)

wendenney said:
			
		

> I chose to use an old coffee carafe I had from a coffeemaker I no longer use figuring they were made to withstand hot temperatures for sitting on a hot plate for hours on end.



Where a highly alkaline substance such as lye is concerned, it's not just heat that causes the shattering problem. It's the etching part that'll spell its sure doom. And the scary part is that you can't predict when the glass will shatter. It's much safer to use PP #5, HDPE or the stainless steel. 


IrishLass


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## soapopera (Apr 3, 2012)

Maythorn said:
			
		

> 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.



Today I've noticed my plain unscented batches had a strange 'yellowing' on the poured surface. I'm quite sure it's DOS developing as there's a slight smell of rancidity coming off from it. The funny thing is the rest of the bars are free from this yellowing. I'm cracking my head as how did this only forms on the poured surface? I've thought maybe it's my lid which might have impurities which dropped on the surface. But after finding this thread, I'm beginning to think it could be from my SS pot. I scrape the last bit of soap from the pot into the mold. And I'm wondering could this be how only the surface starts to yellow. Also I notice my pots sometimes have 'watermarks'. The SS pots I've got was suppose to be from a reputable brand. But now I'm thinking to try switching to everything plastics or silicones (inc spoons) to see if I still have this problem.


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## soapopera (Apr 3, 2012)

By the way, anyone have any insight on melamine ware for mixing oil and lye?


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## Guest (Apr 9, 2012)

ANY kind of glass will shatter or even explode from rapid temperature change.  If enough lye is added at once, to a glass container with cold water, or in an ice bath, it has high risk of shattering.  Its the same reason ice cubes crack in your beverage, and the same reason you're not supposed to pour hot water on a frozen windshield.  Rapid cooling produces the same effect.

You can use pyrex to mix your lye, if care is taken to add it slowly so that the temperature gradually rises instead of spikes.  Its not the lye itself or the high temperature that is causing these accidents, but the rapid spike in temperature.  Heat causes molecules to vibrate and objects to expand.  The rapid spike in temperature causes the surface of the container in contact with the heat to expand faster than other parts of the container and they break apart from the stress.  

B-B-B-Bill Nye the Science Guy!


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## IrishLass (Apr 9, 2012)

bashfulbyte said:
			
		

> ANY kind of glass will shatter or even explode from rapid temperature change.  If enough lye is added at once, to a glass container with cold water, or in an ice bath, it has high risk of shattering.  Its the same reason ice cubes crack in your beverage, and the same reason you're not supposed to pour hot water on a frozen windshield.  Rapid cooling produces the same effect.
> 
> You can use pyrex to mix your lye, if care is taken to add it slowly so that the temperature gradually rises instead of spikes.  Its not the lye itself or the high temperature that is causing these accidents, but the rapid spike in temperature.  Heat causes molecules to vibrate and objects to expand.  The rapid spike in temperature causes the surface of the container in contact with the heat to expand faster than other parts of the container and they break apart from the stress.
> 
> B-B-B-Bill Nye the Science Guy!



But it's not _only_ the temp change that makes using glass - even household Pyrex- dangerous for mixing lye solution. What makes it doubly dangerous is how alkaline substances with a pH of 9 or greater rapidly corrode/etch glass (lye has a whopping pH of 14). Depending on how alkaline the solution is and how resistant the glass is, the corrossion will either be hastened or happen more slowly, but it _will_ happen nevertherless. As one chemistry professor explained it to a fellow soaper on another forum, once the tiny etches have formed, residual sodium hydroxide particles can get trapped or wedged inside those etches and remain even after washing. The trapped sodium hydroxide particles then react with moisture in the air, setting off tiny chemical reactions that cause the etches to form micro-cracks that are nearly invisible to the naked eye, but which can be more clearly seen with a microscope. Over time, the trapped sodium hydroxide combines itself with the glass, slowly forming sodium silicate, which gradually compromises the integrity of the glass even further, until one day as you are mixing another batch of lye solution, 'KABOOM!'- shattered glass soaked in caustic solution everywhere. It may not have happened to you yet, but it has happened to enough soapers that our warnings against using glass for mixing lye solution is more than justified. I know of at least one soaper who even reported their trusty Pyrex lye solution mixing container (at least up to that point) shattering as it was just sitting high and dry right in their cupboard. 


I've posted the following link before by the National Association of Corrosion Engineers earleir in this thread, but I'll post it again:
How Glass Corrodes

It explains how alkaline and acid substances corrode and weaken glass.


IrishLass


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## Stinkydancer (Apr 9, 2012)

I have been using the same Rubbermaid pitchers for ever now- they hold up well.


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## marilynmac (Nov 2, 2014)

Just marking this thread for me because I've looked it up about 5 times already, and it's hard to find.


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## DWinMadison (Nov 2, 2014)

I use a cheap plastic container from Dollar General. Never had a problem. Guess I need to check the type of plastic it is.


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## reinbeau (Nov 2, 2014)

I have a 50 ounce stainless steel pitcher I bought on Amazon for $14.  I never wash it.  I just rinse it well, let it air dry, and make another batch.  Never have any contamination issues.  I'm going to buy another one for resins in the lye, cuz you'll never get it clean again


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## Consuela (Nov 2, 2014)

......the *tupperware* cereal storage containers my mom gave to me...

(she knows...but I still feel slightly guilty because well...you know Mom's and their Tupperware...)

I usually wash them at the end of my soaping session, and rinse them well - they haven't clouded - and the plastic is realy thick. I also use Rubbermaid pitchers too.

I have used the cheap ones from the dollar store - BUT.... one day when I put my thermometer into the solution to check, I left the thermometer in there. Came back half an hour later to lye leaking all over my counter..... Turns out it must have gotten so hot and soft - that the pointy end of the thermometer poked a hole in the bottom of the cheap container...

So.... no more of that...


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## Susie (Nov 2, 2014)

I have 2 stainless steel bain marie type containers I got at a restaurant supply store.  Works a charm, and being stainless, I can use them as double boilers or as an insert for my crockpot, etc.  Should never have to replace them.  Made sure a magnet stuck to them before buying, though.


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