Funkerman23
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Glass Joint grease for acids?
Pardon the dumb title but this question is to the experienced out there: For Nitric or Sulfuric acid distillations( or other lab work with the
concentrated acids) what is your preferred ( or rather recommended) joint lubricant ? would the Teflon joint sleeves do well here? or would the
fluorinated( or high vacuum?) grease be better? I have indeed done a search regarding this but not much luck.. So to avoid contamination I though it
best to ask here.
I thank you all the same.
[Edited on 6-3-2012 by Funkerman23]
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Hexavalent
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Its not a dumb question at all. Personally, I would use either - I have even heard of some users not using anything at all for such materials. I did
hear somewhere on this forum, though, that for HNO3 distillations a tiny amount of H2SO4 can be used.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Funkerman23
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Quote: Originally posted by Hexavalent  | | Its not a dumb question at all. Personally, I would use either - I have even heard of some users not using anything at all for such materials. I did
hear somewhere on this forum, though, that for HNO3 distillations a tiny amount of H2SO4 can be used. |
ehh I
just figured to ask to confirm or to get a fair warning. SO far as I know the fluorinated grease won't react with the acids mentioned, or anything
that the glass itself can handle. But after hearing that Teflon sleeves might result in burst joints( due to thermal expansion) I was hoping to get a
consensus on the validity of that rumor. Either way that goes I know that Teflon ( or PTFE ) won't react t nitric acid or sulfuric. and while a little
sulfuric contamination isn't a critical sometimes you need a purer product.I still hope others with more experience chime in but I guess I'll just
take the plunge and give it a go with the ptfe sleeves.
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entropy51
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I have never seen so many people obsessed with grease, of all things.
When I Google the forum for "grease", I get 302 hits.
Can anything more possibly be said about lubrication?
If so, it would be Krytox, and even that has been discussed.
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Funkerman23
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Update: it seems the sleeves are a much better option. Teflon tape not so much...But still usable.
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Bot0nist
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I have used Teflon tape a lot, but recently had one break when it got hot. I'm sure i just had it to tightly jammed together, so the joint was already
under stress. When the tape expanded slightly with heating, CRACK. A small smear
of conf. sulfuric acid works great as grease for RFNA distillations, and water can be used with a lot of aqueous work and steam distillation. I have
used white petroleum when reactivity isn't an issue. For finicky work, or high vacuum work, use the good stuff, silicone grease or whatever. It's
expensive but a little dab will do ya.
U.T.F.S.E. and learn the joys of autodidacticism!
Don't judge each day only by the harvest you reap, but also by the seeds you sow.
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Pyro
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i personally put silicone gease (tasteless and odourless, i found this out myself)
and if im working with more dangerous things i wrap some teflon tape around the joint once its assembled.
all above information is intellectual property of Pyro.  |
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barley81
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Lowes' hardware sells silicone grease for faucets (i think...) It comes in a little gray stout cylinder with a cap. Has anyone had problems using this
grease?
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Hexavalent
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I think I've heard of one or two people using that . . .IIRC I recently discussed with MrHomeScientist on his video on purifying DCM (my YT username
is 98JMA) about greases and he mentioned he was going to buy some of that and tell us how it works.
Pyro, I will ask - how did you not resist the temptation to eat your lab grease?!
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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MrHomeScientist
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| Quote: Originally posted by Hexavalent | I think I've heard of one or two people using that . . .IIRC I recently discussed with MrHomeScientist on his video on purifying DCM (my YT username
is 98JMA) about greases and he mentioned he was going to buy some of that and tell us how it works.
Pyro, I will ask - how did you not resist the temptation to eat your lab grease?!
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Ah so that was you eh? Yes in fact I did find that grease exactly as described (at Home Depot). I haven't used it yet, but I'll report how it goes
when I do.
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Pyro
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grease isn't the only thing, i found a condenser makes a good lollypop 
well, it wasn't lab grease, it was meant for general use. and i was fixing our kitchen aid, and wanted a grease that didn't taste like anything, and i
had heard that silicone grease is the one, so i put i tiny bit on my finger and touched it with my tongue to make sure it wouldn't taint the food.
back on topic, the grease should be in most plumbing stores and isn't that expensive.
all above information is intellectual property of Pyro. |
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edgecase
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Silicone oil/grease contaminiation is becoming one of my pet peeves. Most of the used glassware I've gotten something tenacious on it that causes
water to bead, it takes a good soak in hot TSP + NaOH + ultrasonic bath, to get rid of it, and there's an oil layer on the bath after doing a batch of
glassware.
I suspect it is silicone oil (they had a spilled bottle of it and looks like they dragged everything through it) the volumetric ware is affected by
this, if water doesn't "sheet" on the glass it's not clean. I've even gotten some new lab glass with a mystery water repelling layer.
So, is silicone oil the likely culprit? I've read that NaOH reacts with it, so my theory is based on the fact that the caustic bath seems to get rid
of it.
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MrHomeScientist
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I just did another DCM distillation today, using the silicone faucet grease from Home Depot. Worked great for me - no leaks detected, and the pieces
were nice and easy to disassemble. Granted, I have no frame of reference because I never took organic chem lab in college so I don't have any
experience with the 'good stuff' Seems pretty good to me though.
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