Hi all,

This question has been on my mind a bit recently as the pet snake tells me hes got some strong base soln in a glass mason jar that will probably sit around for some time. I've read that eventually the glass will degrade and break... Can anyone tell me how realistic this danger is? Thanks a lot, its very nice to have a community to reassure safe teks and discourage dangerous ones. Sorry if this has been covered before, I looked pretty carefully for some definitive answer.

ouro

Well it just so happens that SWIM had her glass break on her and she had jurema and lye-mixture all over her bathroom floor. The glass broke - as far as she could tell - because of the lye. NOT FUN! Good thing she was wearing goggles and gloves!!!
She has another glass container in which it has been sitting for much longer, that didn't break, so we both think it depends on the type of glass. Pyrex seems to be fine.. but who knows.

To be safe I would suggest using HDPE (PE-HD ?) or PP (polypropylene) containers, which are said to be safe to use with lye. If you are using a different base just check on the net to see with what kind of materials it can be stored in. Generally - whatever kind of container it came in when you bought it - that material should work, I think. Most of the times it comes in HDPE jugs, so that's probably your safest bet.

there're no chemicals that could attack glass..it's inert to almost all chemicals known it could be attacked by fluorine,fluoridric acid (HF)and if i'm not wrong by some fluorides. that's all

From Wikipedia:


Not sure if this could really account for SWIM's breaking glass, but SWIM is not going to use glass any more out of superstition. Lye does react with glass, though frosting or freezing of the glass doesn't necessarily sound too dangerous. I think lots of people use glass successfully.
On some data sheet I read not to store high concentrated lye in glass, so that's the advice SWIM will follow from now on. There's got to be a reason for it saying so...

Make up your own mind and - google is your friend!

as the post above says, lye can slowly react with glass, yes. Good quality lab borosilicate will probably be much more resistant than cheap thin glass.

How long does any significant reaction occurs? Enoon, how long was SWIY's lye standing? What quality/thickness glass was it? Did you hit it in some hard surface for it to break? Is it possible what broke/cracked/weakened it was actually sharp temperature changes when you add the lye to water, and not the actual lye reacting with glass? I know that this temperature issue is responsible for a lot (most? almost all?) of problems people have related to lye glass.

Personally I had glass container standing for weeks with lye and nothing happened. I always take care to add lye slowly and mix well as I add it. Also dont use some cheap thin glass and also I avoid bumping it or laying it too strong on top of a hard surface.

Doing extractions in a bathtub or on top of a sink or something that can easily be cleaned is recommended. Remember to always wear protection!!

yeah maybe NaOH could react with glass anyway i think sodium silicate would stuck on glass and forms after long time exposition in high concentration solution.Maybe it could be weaker a bit but i don't think it could became 'crisp'.
i think that thin layer of sodium silicate would protect glass below from further corrosion from NaOH but not sure of it

SWIM's sat for about 4 days until it busted. It was not hit. SWIM was just putting it back to its spot to let it sit for a while, when the bottom just fell off. When SWIM stirred it, she had noticed from day 1 that there was something on the ground. She thought it was lye stuck there, and maybe it was and never got dissolved properly - but that's exactly where the glass broke. It could have been that there was some kind of pressure that built up in the glass as well and added to the effect but She thinks the lye sort of helped the whole process along. The glass was a regular mason jar kind of thing, probably not the best quality, def. not pyrex or borosillicate...

SWIM is going for PP containors and smaller ones at that to make it easier to handle. better do several xtracts in parallel than one big one, she thinks. Let's see how that works...

bottom breacking is tipically due to heating and fast cooling but it doesn't seem your case, a little strange imo

I'm scared of putting NaOH in glass anyway. I'd much rather use HDPE mainly due to the reason I don't like the idea of dropping a glass vessel full of a strongly basic solution. Plastics are much more forgiving.

I've seen borosilicate flasks (Pyrex/Bomex) left to sit for months (too lazy to clean them) with strong lye solution inside and no negative consequences seem to have ensued. YMMV, but borosilicate seems quite inert and resistant to negative effects of strongly basic solutions. I would not be so bold with 'regular' glass such as Mason jars.

-JM

wow, thanks people, that was fast.

this site implies pyrex containers with rubber stoppers are ok for long term lye storage:

http://motion.kodak.com/...essing_h244_sodiHydr.pdf

(I don't really know what the rules on external links are... is there a section on this that I missed?)

and many many sites will state that naoh attacks glass, but slowly. I definitely will not to make a habit of storing strong lye water in glass in the future. Time to sharpen the ol eyes to hunt down some nicely shaped HDPE.

ouro

why storing base in liquid form?

over all, lye takes a VERY long time to weaken glass ime.

External links are fine, just no links to RC's.

Hmmm I have a few mason jars from some stb's that have been sitting full of basic solution for months now. No problems with them so far but I guess I should get around to disposing of them lol.

NaOH will not react with glass in any appreciable timeframe. The problem comes from a hot solution of freshly diluted NaOH creating thermal gradients across the glass in excess of what it can handle, hence it breaks. Borosilicate lab glass can handle these temp gradients far far better as can the old style pyrex. To be safe use labware or HDPE.

Would it be safe to make the lye mixture in a HDPE Milk jug and then transfer to a glass container once it has cooled?

No. Dissolving NaOH releases a lot of heat. The sudden localized heating not only can cause glass to break, it can also cause plastics to melt or otherwise fail. The risks can be mitigated somewhat by employing good stirring, so that lye pellets do not get the chance to become stuck to the vessel and cause localized overheating in that place. IMHO the risks are not worth it. Do not use plastics to make a lye solution.

Ideally, dissolve lye in a stainless steel vessel and stir well, but without splashing. Wear eye protection and gloves. Work in a well ventilated area, because dissolving a lot of lye may force dissolved gases out of the water, creating an airborne spray of tiny droplets of lye water. These are harmful to the eyes and lungs.

When the lye solution has cooled, it can be safely transferred into a glass container. Glass is not attacked very strongly by cool lye solution. The danger lies mostly with the local heating caused by the exotherm of dissolution. Hot concentrated lye is very corrosive, even to glass, but the sudden temperature jump is a much bigger threat to the glass.

From the description of the vessel concerned it sounds as though there was indeed a cake of undissolved NaOH at the bottom of the container. This cake had expanded and thus caused mechanical failure.

Avoid formation of lye cakes by adding lye slowly/carefully enough that it dissolves steadily without settling into a contiguous layer at the bottom of the vessel.

Careless use of lye pellets can also block a waste pipe solidly, which is rather the opposite of the intended effect (believe me, I actually did this once! )

Just keep it in the HDPE container (although I have had the milk jug lid disintegrate after a while). If you must switch to glass then make sure the glass container is quite thick and that you have cooled the liquid. I have kept very high pH basic soup in both glass(demijohn) and HDPE for many years with NO faults occurring in either medium (except the lid of the milk jug)

I use these 2.000 ml glass bottles with wide neck and easy to read scale from Schott Duran. Not cheap but worth the money.

After a long time soaking the sludge in the bottle you should expect at least a bit of degradation of the glass or some erosion. But after washing the bottles with liquid soap they again look like brand new.

The bottles also comply with lots of criteria and quality control.