thereelstory!
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ground glass joint help
i had a hno3 setup that i left sitting in my fumehood for a few months attached. i have had hell getting the joints seperated. any suggestions on how
to get them unattached?
other than hot cold contrast.
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mnick12
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I know this is not what you asked for, but it has always worked in my experience.
Well I had a similar problem once. I have found through trial and error the best method for separating these joints is to first submerge the whole
thing in water then boil for an hour. If this does not work simply allow the the glassware to cool to rt then place the whole thing in the freezer for
a few hours, as the glass cools it shrinks and whatever is stuck pops out (literally).
Hope that helps.
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Eclectic
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Ultrasonic cleaner and a solvent?
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Panache
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smash it into several pieces and use pliers and a screwdriver, quickest way for sure.
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Mildronate
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http://www.sciencemadness.org/talk/viewthread.php?tid=14343#...
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Chainhit222
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When my joints stuck up after atmospheric distillation of sulfuric acid, i just hit that shit with a blow torch for a while and twisted using a pair
of welders gloves, they came apart fine 
The practice of storing bottles of milk or beer in laboratory refrigerators is to be strongly condemned encouraged
-Vogels Textbook of Practical Organic Chemistry
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peach
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Chainhit to the rescue with the simple solution. 
You could try soaking them in water for a day or so. The less you mess around with jammed tapers, and let them soak (in verious things) and fix
themselves, the less likely a broken bit of glass is.
Freeing up stuck tapers can take ages as the things you're using gets through the microscope gap, I spent three weeks plus on one and
still didn't manage. Sometimes a long soak in a bucket of water is enough. If you've had it there for three months, you can afford to wait a few days
more. If not, lesson learned. 
[Edited on 22-9-2010 by peach]
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SWilkin676
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https://www.pai-net.com/secure/catalog.aspx?ParentKey=10054&...
aerochem's dry teflon spray has saved more than a couple of things around here.
I had a stuck stopcock in a sep funnel that wasn't budging after soaking or hot water. I sprayed some of the aerochem in and it came right out.
I also had two stainless steel sinks stuck together for 6 months and finally got them apart using the aerochem.
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peach
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Makes me wonder if stuff like WD40 might save some joints.
As some of you probably know, it wasn't originally designed so much as a lubricant. WD stands for Water Displacing, it was for the Navy to spray into
capillary style joints to get the water out.
I think the primary, very low percentage, component is kerosene, or something similar. I would imagine that may react with some crap stuck between
tapers, and may free them. It may also make things worse if it forms an harder to dissolve tar / solid.
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mycotheologist
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I forgot to grease up a glass stopper and now its jammed in the RB flasks neck. There was a bit of Ca(ClO)2 inside the neck (because I added it
through the neck but didn't do a very good job of cleaning it out before putting in the stopper) which I believe is what caused the stopper to get
jammed somehow. I'm gonna try submerging the flask in boiling water and see how that goes.
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Pyro
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i find the easiest is to put hot water in the flask, fill it to the top, then run cold water over the other part, all my stuck joints have popped
loose like that.
otherwise you could take it to a glassblower
but of course the best solution to your problem is to not leave it sitting there for so long, take it apart as soon as you can. prevention is better
than cure
[Edited on 12-5-2012 by Pyro]
all above information is intellectual property of Pyro.  |
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sargent1015
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Hmmmm...
Quote: Originally posted by Pyro  |
but of course the best solution to your problem is to not leave it sitting there for so long, take it apart as soon as you can. prevention is better
than cure
[Edited on 12-5-2012 by Pyro] |
I agree with Pyro, don't leave it set up! Does this mean you just left the Nitric acid to react and forgot about it? I'd be more careful/attentive
next time.
But, I digress. My preferred way, along with many other Chemists, is to heat the joint up with a heat gun (Hair dryer if you want) and tap the piece
out with something that will not chip the glass but still provide a good whack.
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Vargouille
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I heard something a while back about letting it soak in club soda and heating the joint lightly. Should work fairly well.
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kuro96inlaila
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Boil some water in a kettle,when it boils,pour it slowly on the join.Then twist the two parts strongly but gently and slowly.It always work for
me.
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Fantasma4500
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as chainhit222 said, heat it up with a blowtorch, works wonders.. was just about to order new 29/32 500mL flat RBF and 29/32 distillation bridge
distilling phenol without tightening the whole thing properly, followed by not washing it and then trying to distill chloroform was practically
welding the whole thing shut, noticed the ground glass part turned very white, supposing i managed to decompose whatever was keeping it together
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subsecret
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I distilled nitric acid a few days ago, and I took the apparatus apart immediately afterward, and I found a stuck joint.
Fear is what you get when caution wasn't enough.
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MrBlank1
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I used this technique often with good success, minus gloves (unwisely):
1) Wear a good thick pair of gloves, use oil (I used olive) by drizzling on inner rim of outer joint, then by using thumb and fore finger, try to
gently but firmly rock top piece, containing inner joint, back and forward a dozen times or so.
2) Rotate 90 degrees and repeat 1.
Whilst doing the above, look at the joint, to see if you can see "bubbles/air cracks" appear and disappear with alternating applications of pressure.
These are a sign that the joint may come free (eventually)
It may take MANY minutes to get this to work. I can't remember where I read this info, but I know the oil part comes from freeing a glass stopper from
a brandy "big ornamental bottle". I suspect it comes from Gary S Coyne's "The Lab Companion", which was my go to lab manual. Being an amateur,
probably more appropriate than Vogel's, I believe.
I have used this technique with success many times. Success rate is very high, excluding sep funnels. Success with sep funnels is maybe just over 50%
for an impatient person like me. I had probably 4 or 5 (250-500mL) broken in 4 years, usually from leaving a HCl generator flushed and joined for 3-4
weeks. Very bad form, I know.
But, if you're not breaking ANY glass in the lab, are you really even using it at all? (<--- meant to be humor)
AAAAA = Australian Association Against Acronym Abuse
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