alking
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Help! Frozen joint. I think due to NaOH crystals.
So I added some NaOH into a flask, some crystals got stuck around the edge, and I thought I cleaned them off, but apparently not. Now I have a 400mm
reflux condenser stuck to it : /. I've tried twisting as hard as possible, banging on it rather hard with a plastic bottle, heating the outer joint
with a torch, spraying 70% alcohol around the joint and waiting an hour or two, and I've cussed at it very loudly, but so far no go. The only other
thing I can think of is putting it into the freezer but because the condenser is so big it will not fit. Maybe letting it sit overnight with solvent,
or even days, but I am kind of beginning to think I'm going to have to break my flask. Does anyone have any advice? I really hoping this isn't lost.
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gdflp
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One technique for fixing stuck joints which has been quite successful for me is WD-40. Make sure the joint is affixed vertically, spray some WD40
around the joint then let it sit for 30-60 minutes. That's worked for me every time, though I don't believe I have ever chemically bound them, as you
may have in this case (silicates are quote strong adhesives!). It's worth a shot though. If that doesn't work, heating and cooling the outer joint
several times might help to weaken the bond and eventually allow the joint to separate.
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alking
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Ok, well I was able to get my condesor off finally by twisting at the kneck while smashing at the base and then I got my stir bar out of the flask by
throwing it against the cement floor. I'll have to remember this trick for the future. After smashing it into pieces the damn joints were still frozen
together too, I don't think there was any hope. That condensor was quite possibly my most expensive piece of glass at that : /. Not having a great day
so far.
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chemplayer..
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Heat the ground glass joint directly but gently using a gas flame. Every so often twist the joint firmly and see if it will move. The differential
expansion of the glass caused by the outer/inner temperature difference works well in helping to unfreeze it. Has worked every time for us, especially
with alkali 'freezes' which are apparently quite typical.
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alking
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I had tried that numerous times and it wouldn't budge. It's broken now anyway. Even once broken I couldn't remove the fused joints though. I have only
had stuck joints a couple of times in the past and they were nothing compared to this, though I do believe this was my first chemically fused joint as
opposed to simple thermal expansion and contraction.
Do strong alkali solutions typically cause this or is it likely due to how I loaded the flask (adding crystals instead of solution)? If so are there
any steps I can take in the future to avoid this?
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unionised
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Yes, notoriously.
You can use Teflon sleeves to prevent it.
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alking
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Yeah, I was reading about those earlier, I'll have to pick some up.
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aga
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funny. Today i thought i had my first ever frozen joint.
500ml RBF and the stopper - it would not twist or be pulled out.
I'd put the stopper in while the contents were hot, and this was 30 mins later.
Suspected that the air etc inside had contracted causing a vacuum.
I just heated it up a little and the stopper popped out, yet other glass-destroying scenarios did pop into mind.
Edit:
Second frozen joint. First was a burette which had NaOH in it overnight (lazy/stupid) : the valve stuck so hard that the glass broke whilst trying to
free it with a hammer. That was glass/teflon, so beware NaOH in all cases, not just glass-on-glass.
[Edited on 20-3-2016 by aga]
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alking
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Man, now I'm scared. How much glassware am I going to lose over time?!
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greenlight
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I have had this same thing happen to me years ago by adding sodium hydroxide to a hot flask and the joints freezing together. They are pretty solidly
stuck and I still have not got them apart to this day. I have tried most of the thing listed in the above post apart from smashing them but nothing
worked.
It's never happened again so I wouldn't be too worried, just make sure the joints are always greased especially when sodium hydroxide will be put in
apparatus.
Be good, otherwise be good at it 
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MrHomeScientist
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I've been lucky so far and have avoided any frozen joint mishaps. Just remember to disassemble your apparatus as soon as you can, and grease your
joints.
I now have a feeling of dread that I will return to this thread some day soon with an entirely different story.
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aga
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All glassware can be safely kept forever - just don't use it, ever !
You got to be brave to get anything done.
Try not to be too stupid and it'll all be fine for years.
I've lost most glassware during cleaning rather than actually using it.
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chemrox
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I'm hanging on to a condenser that has a broken joint inside the female 24/40 end. I can't get a purchase on it due to the way it broke and subsequent
attempts to get the male 24/40 part out. I have tried sonication (this is a word), WD 40, vegetable oil, NaOH solution, MeOH, acetone, ligroine,
naptha, etc. I am afraid to heat the joint too much. I want to recover the condenser as it is of a type normally provided in chem class kits. It has
bumps above the bottom joint to hold packing material and I have used it as a column. I have longer better columns but I dislike losing glassware. One
nice thing about is it can be warmed with water circulation directly from a faucet that mixes hot and cold. My last resort is the glassblower. One
other possibility would be to find a rod narrow enough to pass the bumps but stiff enough to whack the rim of the stuck inner joint. I haven't found
one yet.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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szuko03
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I have always had luck with a blow drier / heat gun. It can take a few minutes but it eventually has worked the few times I need it to. But you guys
are probably doing slightly more "hardcore" stuff then me. Still in simple distillations but even i have learned to grease and disassemble when
possible so frozen joint must be at least somewhat common.
Chemistry is a natural drive, not an interest.
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vmelkon
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I once left sodium benzoate solution in a separatory funnel with a stopper for months. It would not budge. I had to leave it in water for a day and it
came off.
While working with calcium hypochlorite, it etched my glassware where the crystals were stuck on the glass and slowly dissolving. The concentrated
Ca(OH)2 must have done it.
A RBF 1 L, I dissolved some NaOH in water. The bottom area where the NaOH was sitting got etched. Nasty stuff!
Signature ==== Is this my youtube page? https://www.youtube.com/watch?v=tA5PYtul5aU
We must attach the electrodes of knowledge to the nipples of ignorance and give a few good jolts.
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chemrox
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Hahaha. I did the same thing with the same flask. Oh well. I didn't pay much for the RBF and they are available and cheap. Besides, if it's truly
etched where's the problem?
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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XeonTheMGPony
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Soak it in Viniger solution, to dissolve the hydroxide, the bubbles keep the water moving and excreting the resultant salts.
Takes time but patience is a virtue in all that sort of stuff.
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100PercentChemistry
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Had that happen to today. A simple heatgun fixed it. I will now buy some lubricant for it.
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