Glass and lye; truth or myth?

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lenarenee

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Speaking of YouTube soapers, there's this:
. Start at 9:25. Bring a beverage and your knitting/crafting/paperwork because her videos are....not concise.

Is he expert enough to know?
 

Cat&Oak

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I watched a few of her videos. Her personality is not my particular cup of tea but she has made a lot of soap and she teaches classes.
 

lenarenee

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I watched a few of her videos. Her personality is not my particular cup of tea but she has made a lot of soap and she teaches classes.
I agree; her style of speech and vocabulary are hard for me to put up with for long. But her minds works differently than mind, and I find myself either re-thinking something I know, or learning something new, or deciding I was correct all along!
 

Babyshoes

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Is he expert enough to know?
He's an expert on glass, but not a chemist as far as I can tell. I know a lot about glass as I work with it a bit, but I'm no expert on the chemical composition or reactions that it's capable of. His description of annealing is perhaps correct for float glass, but not for art glass. I have also seen comments by chemists who claim that a strong alkali *will* slowly etch glass with heat and time. It's not clear if a sodium hydroxide solution is strong enough to do so.

He claims that glass itself is a base and will not react with bases, but when molten it (soda lime glass) *does* react with sodium bicarbonate to create bubbles. It's a reaction I use for decorative effect in my beads. Admittedly I'm not sure if it's more because of a chemical reaction or the extreme heat, or both, but it certainly looks chemical to my untrained eye.

His explanation of heat resistant properties of different types of glass makes sense, but for the average person, it may not always be clear which type of glass they have, and if you get it wrong there is a potential for disaster.

Given the uncertainty, I'm definitely not going to use glass for mixing lye. While it would probably be fine for melting oils and mixing the batter, I just feel safer avoiding it for soap in general, especially since a large glass bowl or jug is heavy enough when empty, I wouldn't want to risk dropping a greasy glass container full of soap batter...
 
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Cat&Oak

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Don't surface abrasions get deeper over time? Also, if people have used pyrex and had it shatter on them, shouldn't that matter?
Yes they do. One of my friends had a Pyrex container shatter all over while she was soaping so just because it has never happened to this person doesn't make it a good idea to use it.
 

violets2217

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Mrs Soap & Clay! Lol… it took me a few tries to get through my first video of hers. I think she uses shock & awe to attract people to her videos. I have Pyrex I use for non soap stuff. I used to heat oils in my big Pyrex. But honestly I’ve stopped using them at all because they are just too heavy. But I never felt safe to use anything glass with my lye solution. This was the first result from a google search: can lye etch glass: #1: using just lye #2 I don’t think I realized lye would liquify when heated?
 

MellonFriend

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Wow. I'm amazed how many people I saw on YouTube using glass. Is raw soap batter okay in glass? I bought a bunch on measuring cups for mixing colors in that are glass. I would hate to just have to throw all of them out. 😞

I can't believe that I never ran into this while doing research on soap appropriate containers.
 

lenarenee

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Mrs Soap & Clay! Lol… it took me a few tries to get through my first video of hers. I think she uses shock & awe to attract people to her videos. I have Pyrex I use for non soap stuff. I used to heat oils in my big Pyrex. But honestly I’ve stopped using them at all because they are just too heavy. But I never felt safe to use anything glass with my lye solution. This was the first result from a google search: can lye etch glass: #1: using just lye #2 I don’t think I realized lye would liquify when heated?
She is....dramatic, that's for sure. The experiment you linked used "molten lye", it was not a lye solution. And heat from a propane torch. So I don't know how it compares: a lye solution just might take longer.
 

AliOop

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I seem to recall older posts on this forum from folks who worked in labs, something to the effect of their need to replace glass beakers within a certain time if they were being regularly used for strong alkaline solutions. Hopefully some of them can chime in to confirm whether that truly is the safety protocol in labs.

But the other issue is the breakability factor. If I drop or knock over an HDPE container of raw soap batter, I have a dangerous mess on my hands. If it is a glass container, the danger factor just increased exponentially. Who wants to clean up caustic soap batter mixed with broken glass?!
 

Zing

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So when I was a noob, I was super careful to follow all the safety precautions including not using glass containers. This was during the time when I was compulsive about the temperatures of my lye solution and oil mix (now I do room temp or "warm to the touch"). I re-purposed my wife's glass candy thermometer and would just leave it in my lye solution. I am embarrassed that my brain understood not to use glass bowls -- but I used a glass thermometer! Yikes-kers. One session, I pulled out the thermometer and it shattered into a thousand pieces in my hand. I was not hurt but just incredibly gobsmacked by my own stupidity!
Yes, I'm typing all of this out loud!! Don't hate on me!!
 

lenarenee

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I seem to recall older posts on this forum from folks who worked in labs, something to the effect of their need to replace glass beakers within a certain time if they were being regularly used for strong alkaline solutions. Hopefully some of them can chime in to confirm whether that truly is the safety protocol in labs.

But the other issue is the breakability factor. If I drop or knock over an HDPE container of raw soap batter, I have a dangerous mess on my hands. If it is a glass container, the danger factor just increased exponentially. Who wants to clean up caustic soap batter mixed with broken glass?!
YES!
 

AliOop

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Awww @Zing we could never hate on you - not the inventor of the alternating wall pour! ;)

Besides, we've all "done stuff." For years, I used vinegar to clean soap spatters off my SKIN - because that was the advice from the blog that taught me to make soap. 😱

Like you have mentioned in other posts, I too had no idea that this forum or other resources existed, or that there was so much science involved. Or money. But let's not go there. 😁😅
 

MellonFriend

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So when I was a noob, I was super careful to follow all the safety precautions including not using glass containers. This was during the time when I was compulsive about the temperatures of my lye solution and oil mix (now I do room temp or "warm to the touch"). I re-purposed my wife's glass candy thermometer and would just leave it in my lye solution. I am embarrassed that my brain understood not to use glass bowls -- but I used a glass thermometer! Yikes-kers. One session, I pulled out the thermometer and it shattered into a thousand pieces in my hand. I was not hurt but just incredibly gobsmacked by my own stupidity!
Yes, I'm typing all of this out loud!! Don't hate on me!!
Yeesh, Zing! That's scary! Now I'm scared all over again. Also. You invented the alternating wall pour!?
 

TheGecko

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I couldn't watch their videos....too much 'rambling'.

From Science Madness.org discussion on this subject: "The NaOH must be a molten solid to eat through the glass. Sodium hydroxide solutions, depending on their concentration, may etch or weaken glass if heated.

Your experiment only uses a sodium hydroxide solution at room temperature, and that does nothing to the glass. If you heat it, the glass may be whitened or streaked. If you want to completely destroy the glass, you need to heat sodium hydroxide until it is molten in a solid state.
"

Now it may take a few years for lye to damage the glass, but that is only one contributing factor to not using glass. Another one is 'thermal shock' aka abrupt temperature changes. And when you add Sodium Hydroxide to room temperature Distilled Water...the water almost immediately increases 150F in just a few seconds. And let's not forget the various implements that we use...stick blenders, whisks, spoons, beaters, etc. Unless you are using plastic and silicone, you're creating scratches in the glass.

Maybe it will never happen, but what if it does? Is it really worth it when it's just as easy and safer to use plastic or stainless steel. Bad enough you have a hell of mess to clean up regardless of whether it's due to failure or an accident, now you glass to worry about.
 

cerelife

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I've never really understood this issue that has been around forever it seems. Specifically, I don't understand why people want to use glass/Pyrex.
Aside from the possibility of breakage, it's far more expensive and cumbersome than using plastic pitchers and bowls/buckets for soapmaking.
Am I missing something?
 

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