Glass and lye; truth or myth?

[violets2217]

Seems like current events would indicate that this is just unfortunately human nature...

Was thinking the same thing….

 

[melonpan]

Invest in a Laser Infrared thermometer. You can get them for around $18-24 dollars on Amazon, Ebay, Walmart, etc. The only thing I would do extra is put a fresh good top brand battery in it, such a Duracell, Eveready, or Rayovac. The Chi-nee supplied batteries are sketchy at best.

These are much more accurate and safer to use because the thermometer doesn't touch the product at all. They're used extensively in the restaurant industry for checking holding temperatures of food on the line. You can choose between Fahrenheit or Celsius readings, they have a backlight option too. Pistol grip is comfortable for any size hand.

View attachment 61306

Thank you for the recommendation! I ended up buying this exact model and today soaping with it seems a different thing, it's very convenient to use. I just need to remember to stir well so that I'm not just taking the surface temperature.

 

[bookworm]

Thank you for this thread.

Has opened my eyes to safety issues.
I use plastic jugs for mixing lye solution.

Melt hard oils - larger amounts in stainless steel pot on stove, and use same pot for mixing soap.

For the smaller quantities though, I'm guilty of melting hard oils in pyrex jugs/bowls in microwave and making soap in same.

So now been looking for microwave suitable plastic containers to melt oils & mix the soap batter.

Can any of you kind souls offer some suggestions as to what you use?

I don't want to use too many containers.

Thank you so much.

 

[Johnez]

Thank you for this thread.

Has opened my eyes to safety issues.
I use plastic jugs for mixing lye solution.

Melt hard oils - larger amounts in stainless steel pot on stove, and use same pot for mixing soap.

For the smaller quantities though, I'm guilty of melting hard oils in pyrex jugs/bowls in microwave and making soap in same.

So now been looking for microwave suitable plastic containers to melt oils & mix the soap batter.

Can any of you kind souls offer some suggestions as to what you use?

I don't want to use too many containers.

Thank you so much.

PP#5 plastic is considered lye safe. It's the number I look for when buying pitchers, measuring cups, or containers. Very easy to find.

Edit- Earlene and Irish Lass just helped me with this:

Just make sure the container is made of Polypropylene (recycle code #5 - US) or HDPE - High Density polyethylene (recycle code #2 - US). Either is good for masterbatch lye solution storage.

Personally, I prefer the very sturdy Essential Depot lye bottles that have child-proof caps for my mb lye solution. One perk is that they are already labled as caustic and NaOh, as well as other safety precautions, but that's only part of why I like them. The size is best for my hands, as they don't hold too much liquid for me to lift and pour.

I premix my lye all the time in a 50/50 solution using distilled water, and so far, I have not had any trouble soaping with it, even
as an experiment I waited over a year to use it. Maybe it was the 'luck of the Irish', but nothing out of the ordinary happened when I soaped with it.

I store mine in a repurposed, well cleaned/rinsed liquid laundry detergent bottle with a no-drip spout, made of HDPE #2 plastic, and I mix my solution beforehand in a large Rubbermaid pitcher made of PP #5 plastic. Just a heads-up: it sure seems to take nearly a gazillion rinses to clean all the residual laundry soap out of the detergent bottle beforehand, so fair warning. My lye solution doesn't go in unless there's not even a single little soapy detergent bubble left. lol

View attachment 61849


IrishLass

 

[earlene]

So now been looking for microwave suitable plastic containers to melt oils & mix the soap batter.

Can any of you kind souls offer some suggestions as to what you use?

I don't want to use too many containers.

For melting oils in plastic vessels in the microwave oven, I use the same vessels I mix soap in (PP or HDPE plastics). Both work just fine for both purposes (melting the oils in the microwave AND mixing lye soap batter.)

Although, sure, Pyrex can be used to melt in the microwave, I don't like it for that purpose because:
#1 it's breakable and I have had too many glass-breaking accidents in my kitchen,
#2 it gets too hot to handle, but most importantly
#3 my microwave oven is slightly above head-height in my kitchen, so I don't like lifting heavy breakable items full of hot liquid down from that height.

Not to mention I'm getting old and weight matters when old hands get weaker and don't grip as well as when I was young & invincible!

 

[dibbles]

Thank you for this thread.

Has opened my eyes to safety issues.
I use plastic jugs for mixing lye solution.

Melt hard oils - larger amounts in stainless steel pot on stove, and use same pot for mixing soap.

For the smaller quantities though, I'm guilty of melting hard oils in pyrex jugs/bowls in microwave and making soap in same.

So now been looking for microwave suitable plastic containers to melt oils & mix the soap batter.

Can any of you kind souls offer some suggestions as to what you use?

I don't want to use too many containers.

Thank you so much.

I had to replace my mixing bowl a couple of years ago and ended up with this one. It is sturdy and I like that there are measurements printed on the inside of the bowl that are easy to read.
https://www.amazon.com/gp/product/B001CDP5VS/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1For larger batches I have something like this, which I also like. I do like the pour spout on this one better than the one on the batter bowl above.
https://www.amazon.com/gp/product/B00UZL2AO8/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1On the rare occasion I make a batch larger than this will hold, I use a repurposed 1 gallon pail.
For smaller batches, I use a 4 cup measuring cup that you can find just about anywhere. I tried one of the Dollar Store mixing bowls, but the handle wasn't sturdy enough for me and I use it for other things. A lot of people use those and like them, so it isn't a huge investment if you want to try one to see how it might work for you.

 

[CreativeWeirdo]

Lye-safe containers:
Stainless Steel
High Density Polyethylene (HDPE): recycling number 2
Polypropylene (PP): recycling number 5

Katie Carson has a very approachable Lye 101 video on her Royalty Soaps YouTube channel (Here is the link: )

 

[Mistrael]

I mostly make 1 & 2 kilo batches, so mixing bowls & cups & silicone utensils from Dollar Tree work great. If I'm ever able to go bigger I would buy good restaurant grade containers. The Webstaurant store seems to have a lot of good stuff and reasonable prices, so if I didn't have a local restaurant store that's open to the public - or if I'm refusing to people that week - that's where I would start. I've tried buying containers from Amazon but usually end up with the wrong type of plastic.

 

[linne1gi]

Oh no, not this subject again. lol We have so may threads and posts on this issue going back years.

In all my research and listening to different experiences of various chemists and those that work in labs who have had their glass lye storage bottles dissolve bit by bit over time from the lye......but more importantly, listening to the many soapers who have had their Pyrex shatter on them when working with lye.... my own stance, as well as the official stance of the Admins here SMF remains the same....soaping with glass is just asking for trouble. I liken it to playing a game of Russian Roulette. You may have nothing happen for several soaping sessions and be lulled that all the warnings must be bunk, but we've had one too many soapers chime in with their experiences that have proven otherwise, and so it's not something we recommend. If anyone wants to do it anyway, that's their own business and they are certainly free to take that risk and do so, but we will continue to warn of the dangers.

Here are some links to just a few of our members have posted in regards to their experiences of having had their Pyrex go kaboom on them when soaping, or in the dishwasher, or just sitting in the sink or cupboard (there are more, but these are enough to suffice):

Forum member BlueberryHill from 2015:


From forum member Raha from 2010:


From forum member Deda from 2010


Forum member Paillo from 2011:


Forum member Candybee from 2013:


Forum member Newbie from 2016:


If the Dish Forum was still around, I could send you a bunch of links to shattered Pyrex experiences during soaping from the members there, too, but unfortunately they are offline.

Anyway, like I've posted before in other threads, glass is pretty strong stuff, but there are four things that are its 'kryptonite (if I can borrow from Superman jargon), i.e., things that aggressively attack it and weaken its resistance, causing it to actually corrode and even dissolve layer by layer:

1) Hydroflouric acid
2) Concentrated phosphoric acic (when hot or when it contains flourides)
3) Hot concentrated alkali solutions of at least 9 pH (lye has a pH of 14)
4) Superheated water

Of the above 4 things, the thing that concerns us as soapmakers of course is #3, alkali. Alkalis affect the surface of glass by directly attacking the silica that the glass is made of, leading to its dissolution, little by little, over time as the surface of the glass is repeatedly exposed to the alkaline solution. And the rate of corrosion increases if the hot alkaline substance is agitated, such as when being stirred.

The above corrosion happens to all glass with the repeated exposure to hot lye solution- even borosilicate. See the following safety sheet on borosilicate glass....scroll down to 3.3 under Chemical Composition:
https://www.scilabware.com/en/glass-types-properties
Here's a quote from that link: "Only hydrofluoric acid, hot concentrated phosphoric acid and strong
alkaline solutions cause appreciable corrosion of the glass." [emphasis mine]

Also this in regards to borosilicate glass: Glass Properties
"Resistance to alkaline solutions is moderate and strong alkaline solutions cause rapid corrosion of the glass, as does Hydrofluoric acid and hot concentrated Phosphoric acid." [emphasis mine]

See also the following in regards to how glass corrodes: Glass corrosion "Glass is resistant to most acids but is highly susceptible to attack by alkaline materials, especially a concentration of OH- ions giving a pH greater than 9.0. The result is an attack of the network forming silica-oxygen (Si-O) bonds, leading to dissolution of the glass surface." [emphasis mine]

While it's true that borosilicate glass is stronger and more resistant and takes a longer time to weaken than soda-lime glass, its still chemically vulnerable to concentrated alkaline solutions and will dissolve bit by bit with every exposure until it reaches the point of no return, aka, 'kaboom!'. The problem is that it's impossible for any of us to know when the shattering day of reckoning will arrive until it actually arrives. You may be willing to take that risk, and that is your choice, but I for one will continue to 'proselytize' about it so that those who are new to the craft and haven't yet been made aware of this issue will at least be able to make an informed choice when deciding what kind of vessels to use to mix lye or in which to soap.


IrishLass

Thank you Irish Lass. It happened to me, and let me just say that is one heck of a mess to clean up. Glass shards and hot lye solution are not a fun combination. Especially on the dining room table. I’ve been proselytizing for years and I would say most people just don’t believe it can happen. This happened way back in 2013 when I was making soap for only about a year. I had worked in a chem lab in college and we used borosilicate glass all the time with no problems, but as you said, you just never know at what point it will shatter. Thanks for your diatribe!

 

[bookworm]

Thank you so much, to all of you for your kind assistance.

@dibbles, I have been coveting the Oxo bow for sometime but have not been able to source microwave usage information for it. I contacted my local kitchen store who advised against microwave use. I’m glad that it’s working for you.
I will look into the dimensions of the jug you listed to see if it fits in the microwave oven, thank you so much.

In the meantime I used a few buckets on Saturday with the #5 rating and was pleasantly surprised.
The oils melted in a fraction of the time of the Pyrex, in the microwave.
And of course as Earlene mentioned, there was no issue of hot and heavy glass jugs/bowls.

I am so glad and thankful that this subject has reappeared.
For myself as an inexperienced soap maker, this forum is a mammoth source of information and education.

Looking at some YouTube videos where soakers use Pyrex, I did not know better.

Thank you all once again.So grateful for your sharing

 

[Motherofmoe]

So “she” is an actual chemist/scientist with degrees.
She is referring to hobbiests who make their own soap and yes glass is as safe as glass can be in the hands of whomever is using it.

 

[TheGecko]

So “she” is an actual chemist/scientist with degrees.
She is referring to hobbiests who make their own soap and yes glass is as safe as glass can be in the hands of whomever is using it.

And your point is what?

 

[mrssoapandclay]

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...

Expert on glass + chemist = bases covered. I’ll never stop being dramatic, though; it’s fun for me.

She says in one of her videos that if someone tells you that lye etches glass,

“then just stop talking to them. We don’t talk to those people. It’s horse-$h1t. Lye does not etch glass.”

What a delightful thread to stumble upon.

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.

Dramatic IS my middle name, so. I find this thread delightful, especially given this link to the molten lye test. Soapmakers and the scientific community are forever at odds, it seems.

 

[AliOop]

Soapmakers and the scientific community are forever at odds, it seems.

Hey, so glad you have joined SMF! I love your "making sugar scrubs from soap shreds" video - I started a whole thread here about it and have had a lot of fun with that recipe. So thank you for that!

Regarding soapmaking and scientists always being at odds, according to their website, the maker of Pyrex and other borosilicate glass says this:

Expansion borosilicate glass has a very high resistance to attack from water, acids, salt solutions, halogens and organic solvents. Only hydrofluoric acid, hot concentrated phosphoric acid and strong alkaline solutions cause appreciable corrosion of the glass.

I personally find the science fascinating, so if there's more to that issue that isn't covered by that quote from the manufacturer, I hope you will explain further.

 

[mrssoapandclay]

Hey, so glad you have joined SMF! I love your "making sugar scrubs from soap shreds" video - I started a whole thread here about it and have had a lot of fun with that recipe. So thank you for that!

Regarding soapmaking and scientists always being at odds, according to their website, the maker of Pyrex and other borosilicate glass says this:

Expansion borosilicate glass has a very high resistance to attack from water, acids, salt solutions, halogens and organic solvents. Only hydrofluoric acid, hot concentrated phosphoric acid and strong alkaline solutions cause appreciable corrosion of the glass.

I personally find the science fascinating, so if there's more to that issue that isn't covered by that quote from the manufacturer, I hope you will explain further.

Glad you had fun with the sugar scrub playlist! Testing recipes is always a good time.

I mean, the manufacturer’s CYA statement doesn’t really need more explanation - I think the problem lies with a confusion/bastardizing of scientific terms in the soapmaking community. Lye is a strong alkali, yes, but making a strong alkaline solution involves higher amounts of lye and lower amounts of water than we can use or need to use in the creation of soap. The strength of a solution (where you combine two or more things to create a mixture) depends on the concentration (and is then determined by how much acid is needed to lower the pH to 4). What lye concentration do you tend to soap at - 25%? 33%? Even at a 1:1 ratio, you’re still not creating what would be considered a strong alkaline solution.

But even using concentrations we are familiar with for soapmaking: if you continuously store a 30% alkaline solution in a borosilicate container maintained at 100 degrees for a year, it degrades the glass .05 - .1mm a year. There are similar findings regarding plastics. These findings exist because tests have been conducted. I prefer to rely on quantifiable evidence over some story I read online about Pyrex exploding in someone’s hand and they determined that lye was DEFINITELY the culprit.

Granted, the company statement above is regarding borosilicate (which they manufacture to be used in science and medical labs, so see my CYA comment above as to why the statement is even necessary) and not tempered, but the same holds true for both. There are countless threads all over the internet - in scientific, glass etching, and glass manufacturing forums - discussing the various ways people have attempted to use lye to damage the surface of glass (single pane annealed at that) all concluding that lye is not an efficient compound to do so.

It only seems to be in the soapmaking world that glass is scary. And that’s ok; soapmaking does not require this knowledge base, and glass isn’t strictly needed to make soap. But it IS as safe to use as any other container that’s discussed in these forums, and anyone that draws that weird line in the sand and says otherwise doesn’t understand how stuff works and is relying on anecdotal evidence to support their flawed claim. Which is also fine; they can use their plastic containers and navigate those consequences. It’s just weird that soapmakers continue to make this a thing.

Should’ve put a TLDR in here for those that say I’m not concise. I’m not gonna, though. I was built for long form and like to talk.

 

[CecileBC]

Couldn't watch this video.... could anyone go through the whole thing without pressing "forward" every ten seconds ? I probably missed all the important info as a result, but it was just...too much. I usually watch people like Eli's Everyday or Holly's soapmaking, who send more "focused" and calm vibes... Different people, different moods, different minds, it takes all to make a world

Happy holidays to those who enjoy a summer break !

 

[AliOop]

Wait, what? The discussion of glass is BANNED? That’s some wild gatekeeping. So is it like all things science and rational thought that are banned, or…?

Nope, the discussion is not banned. The official SMF position is that glass is not recommended, but discussion of the science and the practical considerations is allowed.

I personally haven’t seen anything scientific that contradicts the manufacturer’s website about lye solutions etching borosilicate glass. But I and many others here are always open to hearing and learning more. So I hope you are able/willing to contribute to the discussion.

EDIT: just saw your prior comment with the long-form explanation. Thank you for being as wordy as I am! I actually use a 40% lye concentration in almost all my soaps, but it is room temp bc I masterbatch at 50%. And my understanding is that temperature does make a difference here. Any chance you would share a link or two to the articles/experiments you mentioned? Thanks!

 

[mrssoapandclay]

Nope, the discussion is not banned. The official SMF position is that glass is not recommended, but discussion of the science and the practical considerations is allowed.

I personally haven’t seen anything scientific that contradicts the manufacturer’s website about lye solutions etching borosilicate glass. But I and many others here are always open to hearing and learning more. So I hope you are able/willing to contribute to the discussion.

That’s not what their statement says, and I just did. Have fun!

 

[Zany_in_CO]

Wait, what? The discussion of glass is BANNED? That’s some wild gatekeeping. So is it like all things science and rational thought that are banned, or…?

Oh gosh, no! I have been a member of many forums and groups since i made my first soap in 2004. If nothing else, SMF is a science-based forum like none I've ever seen before to feed the souls of all those mad-scientists here.

Just have a look at @DeeAnna 's SOAPY STUFF. It is a treasure trove of the science behind all things soaping related.

 

[AliOop]

That’s not what their statement says, and I just did. Have fun!

Thanks, I just saw your other comment and do appreciate the info.

The person who said the discussion was banned here is flat-out wrong - it is not banned.

Like every other forum, there are always some members who misstate things, whether innocently or bc they love stirring up stuff and getting folks riled up. For the latter, my policy is to ignore them bc nothing productive comes from engaging.