Sciencemadness Discussion Board - Unfreezing glass joints?

Unfreezing glass joints?

LD5050 - 9-10-2017 at 14:18

I have a problem, the glass thermometer adaptor is now stuck to my glass distillation head adaptor and I can't remove them from each other. Usually if this happens I lightly heat the joints with a butane torch and they will come apart but this one is being stubborn. Any ideas on how to get them apart? What do some of you do in this situation?

100PercentChemistry - 9-10-2017 at 14:23

Place in boiling water for awhile and then cool it in the freezer? The water might help to get in between the cracks and then the expansion/contraction during the heat change might pry them apart. I haven't tested this though.

Chemetix - 9-10-2017 at 14:53

WD40, a bit of heating and cooling, and a bit of tapping with a wooden dowel. Glass is slightly elastic, the tapping can bounce apart the point of friction that is holding the joint shut. The WD40 is a good lubricant which eventually penetrates between the closest of joins.

j_sum1 - 9-10-2017 at 15:06

Chemetix is a glass worker. I'd take his advice on this one.

LD5050 - 9-10-2017 at 16:04

Awesome thank you chemetix only thing is I don't have any w-d40 so my next question is how do I synthesize it..? Ha kiddingg

Magpie - 9-10-2017 at 17:36

1. Try rapping with wood dowel.
2. Cool inner piece with ice water, solid CO2 in acetone, or liquid N2. Then heat outer piece with boiling water, silicone oil, or heat with torch and quickly twist.

Let us know what works.

[Edited on 10-10-2017 by Magpie]

JJay - 9-10-2017 at 17:49

I've had this happen before. Usually hot water and tapping with a rod is enough to get them unstuck, but if you were using high temperatures when they got stuck, you might have to use a blowtorch.

Disclaimer: I broke an expensive Kontes distillation adapter yesterday with my bare hands when trying to remove the thermometer adapter from it. Don't use too much force.

[Edited on 10-10-2017 by JJay]

DrP - 10-10-2017 at 05:38

I'll second/third the tapping/heating suggestions..

..with regard to the lubricant, if the heat and vibration do not work, I seem to remember a soak in a base bath can make things really slippery... I do not know if a good long soak in a base bath will help or not - might be worth a try if nothing else works. It would take time to work its way into the joint probably, but could help.

JJay - 10-10-2017 at 06:43

I managed to melt a clip over a joint yesterday, causing the joint to freeze, and separated it by simply scraping off the molten clip, running hot water over the joint, and tapping it with a stir rod while periodically trying to rotate the joint. A base bath will make some substances slippery but can make things worse with frozen joints; I definitely don't suggest it.

DrP - 10-10-2017 at 07:48

Quote: Originally posted by JJay

A base bath will make some substances slippery but can make things worse with frozen joints; I definitely don't suggest it.

OK - thanks.... I was suggesting it as a last resort if all else fails really.

VSEPR_VOID - 10-10-2017 at 09:55

Quote: Originally posted by Magpie

1. Try rapping with wood dowel.
2. Cool inner piece with ice water, solid CO2 in acetone, or liquid N2. Then heat outer piece with boiling water, silicone oil, or heat with torch and quickly twist.

Let us know what works.

[Edited on 10-10-2017 by Magpie]

Is there a danger of thermal shock using solid CO2 in acetone to unfreeze glass joints?

LearnedAmateur - 10-10-2017 at 10:33

I know it doesn't help you with this issue, but for the future, it's good practice to lightly grease (at least) the male joint - petroleum jelly is perfect for this as it is quite inert, and can be found cheaply and commonly. Not only does it help with separating the joints, but it creates a better seal so gases and such are less likely to leak, quite common during reflux and distillation, I find.

NEMO-Chemistry - 10-10-2017 at 10:58

Again for the future, i got sick of pet jelly dripping into reactions etc, i got sick of frozen joints and breaking new bits of glassware. In the end with a heavy heart i splashed out on the dow corning high temp vac grease. i tend to over use the amounts but i got to say its been worth every penny.

maybe i am heavy handed with pet jelly, but with me it just melted and got into everything, at least the dow stuff dosnt seem to do that, be warned its a bitch to clean off though

Texium - 10-10-2017 at 13:30

A paper towel with hexanes or petroleum ether will easily remove high vacuum grease if you're having trouble with that. I still don't often grease joints though to avoid contamination and make cleanup easier. I've never had one break on me as long as I've gotten the apparatus taken apart immediately after being finished with it.

NEMO-Chemistry - 10-10-2017 at 13:51

Quote: Originally posted by zts16

A paper towel with hexanes or petroleum ether will easily remove high vacuum grease if you're having trouble with that. I still don't often grease joints though to avoid contamination and make cleanup easier. I've never had one break on me as long as I've gotten the apparatus taken apart immediately after being finished with it.

Great tip thx, both solvents mentioned are about the only two i havnt thrown at it!! typical

.

I finally found a reasonable priced supply of hexane as well.

SWIM - 10-10-2017 at 13:53

Some pro here, I believe it was Woelen, recommended wetting the joints with the solvent used in the reaction if you don't want to, or can't, use grease.

I've tried it since then, and it works pretty well for sealing and lubricating joints.
I still use High vac grease for very high temps.
Vaseline (petroleum jelly) works for some things, but there's a certain temperature (different with different brands probably) where it gets too thin and runs out of some joints.

It's worth pointing out here that there are tight joints and there are TIGHT JOINTS.
Some glassware (usually better brands; the big domestic and European makers and a few of the best Chinese companies like Laboy) seems to have tighter, smoother joints than others.

These need less grease and are also less likely to seize in my experience. If you assembly the joint clean and dry and rotate it slightly you can feel the difference in that it's smoother to turn.

I have used a very light grinding with toothpaste to make low budget glassware less likely to stick.
It can be done without ruining the universality of fit if you only do a VERY light grinding.

I think it just takes off the tips of very tiny high points from the factory grind being too coarse.

Maybe this last is not as good an idea as I believe it to be, and I welcome any comment as many here probably know better than I.

Magpie - 10-10-2017 at 14:21

I just freed a very tight 24/40 joint of an adapter with a Chemglass 250ml rbf.

I had sealed the joint with con H2SO4 only. But I had made oleum and I supposed some HPO3 had penetrated the joint. I tried ice water in the rbf to expand the outer plus propane torch on the inner to shrink it. I realize now that this is the opposite of what I should have done!

Concludeing it was a chemical fusion with the glass I poured acetone on the joint then rapped the neck on the ss sink edge. I then twisted wheupon I detected a slight slip. Twisting again it broke it loose.

diddi - 10-10-2017 at 18:12

WD40 for me. even if it takes a few days to soak in, it works every time. Scored a lovely condensor because the previous owner could not get it apart and couldnt be bothered trying the WD

Chemetix - 10-10-2017 at 20:08

For a final endorsement for the ol' WD, I found it takes off silicon grease like a charm as well. If hexane isn't at hand. And SWIM has a good point about giving a fine polish to the joint, and I'd say you are on the money with not getting carried away with the polish and loosing the interchangeability.

I have some silica flour (Inhalation hazard!) that I use with water as an abrasive for fine grinding borosilicate glass joints, which are indeed less prone to seizing once polished a bit than a rougher joint.

LD5050 - 16-10-2017 at 18:11

So I tried using wd-40 letting it sit for a few days heating etc. and I still couldn't get it to budge. So I then got some crushed ice and filled the inner joint with ice and water and heated outer joint with torch like magic it came apart like it was never stuck.

DrP - 9-1-2018 at 03:42

Quote: Originally posted by NEMO-Chemistry

Again for the future, i got sick of pet jelly dripping into reactions etc, i got sick of frozen joints and breaking new bits of glassware. In the end with a heavy heart i splashed out on the dow corning high temp vac grease. i tend to over use the amounts but i got to say its been worth every penny.

maybe i am heavy handed with pet jelly, but with me it just melted and got into everything, at least the dow stuff dosnt seem to do that, be warned its a bitch to clean off though

Haven't had to use them for years - but you are right... maybe you put too much on. What about PTFE tape? That can seal the join without it sticking and it won't drip...

PirateDocBrown - 9-1-2018 at 09:10

Don't get too rough with it.
Don't be afraid to set it down, and try again another day. It's amazing how it can change on a second or third try.
Hot water and a fridge have always worked for me.
I do use very light silicone grease on most joints.

ninhydric1 - 9-1-2018 at 09:24

Silicone grease is the my preferred method for greasing joints. If a joint gets stuck, I just use heat a little bit of tapping of the inserted joint.

LD5050 - 10-1-2018 at 07:27

I read di electric grease has the same ingredients as Corning high temp grease. So I bought some of the di electric grease and it works great.

Dr.Bob - 10-1-2018 at 12:04

I have had luck on some joints with a sonicator. If you fill the entire flask or item and sonicate the daylights out of it, an hour or two day over a few days, sometimes it will just pop apart with enough shaking. I have had 50% success of late with that trick. Next step is heating the outer joint with a torch on the two that failed to come apart. After that comes the hammer...

j_sum1 - 29-1-2020 at 04:22

I dug up this thread because I have some problems with a sep funnel stopcock. I don't want to get rough since it is my only one. I am nervous tapping and heating because that is precisely the location where stresses can concentrate. I have it soaking in an acid bath. We will see what it is like in the morning. I am open to suggestions if anyone has any.

woelen - 29-1-2020 at 05:35

Not fun at all, those frozen joints. In that way, I lost a very nice round bottom flask and adapter from my distillation setup. I distilled PBr3 in it and this requires fairly high temperatures (170 C or so). Liquid crept between the joint of the adapter and the flask and this dried out, and red phosphorus formed in the joint. After distillation, the adapter and flask literally were united into one piece with a lot of red P between them at the joint. I tried soaking in bleach (this dissolves red P) and used acid, with dissolved Cl2 in it. Nothing helped, the liquid simply did not reach the joint. In despair, I carefully used a small wooden hammer to release the joint. At a certain moment, I heard a bright "tick" and that was the end of both flask and adapter

Right now, I am very reluctant to distill liquids, from which solid matter can be released (either dissolved or from chemical decomposition), which gets stuck between two pieces of glassware in a joint.

Swinfi2 - 29-1-2020 at 10:13

If your sep funnel is like mine I can see why it would make you nervous.

I think the best bet would be blowtorch and applying consistent twisting just hard enough for it to pop when the heat gets to the right depth.

Or if that doesn't work you could hold the tap with some cork in vice and try a gentle tap out with a mallet? (So the force is confined.)

Best of luck.

unionised - 29-1-2020 at 11:05

There is a simple solution to this issue.
You need two things
A time machine and these
https://www.fishersci.co.uk/gb/en/products/IZ8Q7S29/glass-jo...

You go back in time and then set up the distillation or whatever using the PTFE sleeves.

{Note; no responsibility is, was, or will be accepted for temporal paradoxes}

SWIM - 29-1-2020 at 13:07

I do believe I've got like the worst stuck joint ever.

It's a 45'50 joint, but the outer joint has a vacuum jacket around it so heating is a problem.
can't get to the stuck joint from the inside of the apparatus to try to knock it loose either because there are fragile little glass tubes in the way.

I've wondered about heating the whole thing to 200C or so in the oven and then dipping the end of the stuck joint in cold water, but if it cracks and doesn't come loose I'll have a useless piece of glassware.

Also, I don't want to take any chance on breaking the vacuum jacket which would not only make it useless, but make a bit of a mess as this vacuum jacket is a big one.

The stuck inner joint piece is a 45/50 to 24/40 adaptor, so I can use the item (distillation head) as is even though it's less than ideal, but it is an annoyance. And one that has not yielded to WD-40 treatments.

I've even thought about just cutting the adaptor off flush with the vacuum jacket and grinding the inside of the 45/50 inner joint out so it'll seat a 35/40 inner joint inside it.

Without proper tools that sort of thing takes ages, especially if you expect it to hold vacuum fairly well.

j_sum1 - 29-1-2020 at 13:29

Quote: Originally posted by unionised

There is a simple solution to this issue.
You need two things
A time machine and these
https://www.fishersci.co.uk/gb/en/products/IZ8Q7S29/glass-jo...

You go back in time and then set up the distillation or whatever using the PTFE sleeves.

{Note; no responsibility is, was, or will be accepted for temporal paradoxes}

Ok. I went back in time and tried these things out. Problem is that they don't work on a stopcock.
I got back and now there's two of me and I am my own grandfather. What do I do now?

Chemetix - 29-1-2020 at 14:47

I've had success (sometimes) removing a stuck adapter by using a long bolt with some sort of flat edge on it. This is inserted inside the stuck joint and useing the flat edge to sort of hook onto the bottom of the joint. With a tapping motion on the bottom edge the stuck joint is forced up and out. I'm not sure why it works when everything else has failed but it has worked as a last resort. DMSO has also proved quite beneficial; just a drop on the top edge and it penetrates and dissolves just about anything. NMP or DMF could be substituted or used in conjunction.

j_sum1 - 29-1-2020 at 16:52

Thanks for the tips Chemetix.

An update.
After soaking in acid overnight it was still stuck. But in some subtle way it felt a bit different when I put pressure on the stopcock. I soaked it in boiling water for a few minutes and after that it loosened easily.
My next course of action was going to be WD40 for a few days followed by freezing and then heating the outer with a hot air gun. And of course more tapping with a wooden stick.

outer_limits - 3-3-2020 at 10:16

Quote: Originally posted by j_sum1

I dug up this thread because I have some problems with a sep funnel stopcock. I don't want to get rough since it is my only one. I am nervous tapping and heating because that is precisely the location where stresses can concentrate. I have it soaking in an acid bath. We will see what it is like in the morning. I am open to suggestions if anyone has any.

Happened to me few times. Glass stopcock was impossible to move and after trying few times I gave up trying using force. Instead, I put some joint grease on the external part and waited one day. After this time the grease managed to get into the internals and I was able to disassemble.

Now, after those accidents I always use some grease on glass stopcocks after washing. Personally, I think that PTFE ones are much better regarding the friction and such problems

Jenks - 8-8-2022 at 18:33

I had what must be a common problem - a round bottom flask frozen to a reflux condenser due to exposure to hot base. No amount of heating, cooling or coaxing would separate the two. After learning about cutting non-borosilicate glass by repeatedly heating and cooling a scratch, I thought I would try the same with this. Sacrificing the flask, I made a series of scratches along the length of the outer 24/40 joint using a carbide cutting disk meant for a dremmel, but installed in a regular drill. I did this because the dremmel was too fast, and I wasn't trying to cut the glass, only leave a decent scratch. Then I heated the flask to a few hundred C (below any redness) in a torch and cooled it in a pan of ice water. The heated glass only made a slight sizzle in the water. After only a few cycles I noticed cracks in the outer glass joint, though they weren't really along the scratch marks. After about five heating and cooling cycles, pieces had fallen off and I was able to pry off the remaining pieces and recover my condenser intact. I hope this success can help other chemists recover something useful from their glassware graveyard.

teodor - 9-8-2022 at 01:46

Last few weeks I had some success separating pieces frozen due to the long keeping of alcoholic base solution inside. It's just several hours of WD-40 around the joint and fast heating with a heat gun set to 650C of the outer surface. WD-40 evaporates inside the joint and the alkali residues at this temperature become liquid but very-very viscous, so a lot of rotating force is required. Some pieces of glassware which already had internal cracks didn't survive.
With more experience, I think it is possible to separate pieces with less force. I suspect that the melting temperature of "glass" formed by NaOH/KOH inside the joint is much lower than that of borosilicate glass.

If you need to make an inner part separated there is no need to cut the outer part, just heat it and then pour some water, it will develop cracks.

solo - 9-8-2022 at 04:26

.....i recently open glass joint of a jar long left ecause unable to open...theni tried putting liquid dish soap ....and suprise !!....it opened up quite easy....solo

PirateDocBrown - 9-8-2022 at 05:23

You only need the tiniest amount of Dow grease for your joints. I have a tube I bought for 20 bucks, I think they are up to maybe 35 now. It has lasted me my entire career.

You need just enough that you can see the film of grease when the joints are together. Normal soap doesn't take it off, so after your wash your glass there's likely a bit still in there, so you need even less. It's only when you wash with solvent that you need a full dab.

If you get too much on one joint, use the excess by spreading it around on joints of the opposite gender in your apparatus.

Really, an amount equal to a drop of water ought to be enough for a simple distillation apparatus. Maybe less.

I almost never get stuck joints.

Organikum - 9-8-2022 at 17:48

The cheapest thinnest kind of PTFE tape, 10 mm wide usually and 0,1 mm thick and a tiny amount of spit on the finger to make it stick and thats it. No grease anymore, well very rarely, might not do for very high temps but for the rest it is just fine.

Overlap the tape one mm or two and keep the wrapping flat not to create a easy spiral staircase for stuff to travel, put in socket and give it a quarter rotation pressing down hard, then leave it alone so possible.

The sleeves are just street robbery.

/ORG