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Elementary
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Joined: 18 Apr 2005 |
Posts: 100 |
Location: UK |
3449.86 Points
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Glass Stopcock Lubricant ?
Fri May 06, 2005 3:18 pm |
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I have recently aquired a separating funnel with a glass stopcock. I have heard that strong alkalis will attack glass and possibly cause the stopcock to jam.
Are there any suitable lubricants I can apply to the stopcock before use that will prevent it from jamming and will also not dissolve in toluene ? |
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Joined: 26 Mar 2005 |
Posts: 77 |
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2681.50 Points
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Re: Glass Stopcock Lubricant ?
Fri May 06, 2005 7:01 pm |
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Silicon grease works. Buy it from a lab supplier. |
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2spun
The Resistor
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Joined: 17 Feb 2005 |
Posts: 172 |
Location: daMaGe'd |
3344.98 Points
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Sat May 07, 2005 3:44 am |
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Elementary,
yes very much so use a lube swiy was in a hurry use'd his nice new 1000ml
sep fun- (did not use lube) set it down for a few hrs. went to clean it. busted his nice new stopcock.
now swiy has to get some mapp gas and go hot. if that don't work well he has to come out of pocket$$. |
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bio
Working Bee
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Joined: 13 Feb 2005 |
Posts: 236 |
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9718.84 Points
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Sat May 07, 2005 12:45 pm |
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I gave up on glass stopcocks long ago but give PTFE tape a try. The thin white stuff stretched tight and maybe no overlap. Teflon tape works great instead silicon grease on ground joints even under vacuum if properly applied and also you can get teflon paste and standard taper sleeves.
Worth a try and won't get into everything, being very difficult to get off if a little too much is used. |
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primathon
modified
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Joined: 23 Mar 2005 |
Posts: 190 |
Location: Unknown |
98616.26 Points
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To Grease a Stopcock.... by Tchaikovsky....
Sat May 07, 2005 8:34 pm |
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Greasing a glass stopcock is not that difficult. Remove the stopcock, and lightly cover the entire surface in a very thin layer of pure silicon grease (or if you have access to lab-specific lubricants, Apiezon M or N) with your fingertip. This process can be improved upon by heating the stopcock with a heat gun beforehand, so the lube gets into all the little nooks and crannies. Insert the stopcock back into it's mount, and twist repeatedly until you are satisfied the lube is getting everywhere it needs to. There should be no bubbles or streaks. If you do get streaks, adding more grease is not the answer. Remove the stopcock, clean both it and the mount with hexane (or another suitable solvent), wipe clean, and try again. |
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Elementary
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Joined: 18 Apr 2005 |
Posts: 100 |
Location: UK |
3449.86 Points
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re: Glass Stopcock Lubricant ?
Sat May 14, 2005 9:24 pm |
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Is silicone grease not soluble in toluene ?
Can't seem to find chemical resistance data for silicone grease on the web
I really don't need grease contamination in my non polar. |
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Re: re: Glass Stopcock Lubricant ?
Sat May 14, 2005 10:50 pm |
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Elementary wrote: |
Is silicone grease not soluble in toluene ? I really don't need grease contamination in my non polar.
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Well, I don't know the exact solubility, but if you use silicone grease lightly, most of it does not seem to come into contact with the toluene and does not seem to be removed from the ground glass joint in a hurry. From empirical evidence I would say that it works. |
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IndoleAmine
Dreamreader Deluxe
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Joined: 09 Feb 2005 |
Posts: 681 |
Location: Bahamas |
18717.10 Points
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2spun
The Resistor
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Joined: 17 Feb 2005 |
Posts: 172 |
Location: daMaGe'd |
3344.98 Points
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re: Glass Stopcock Lubricant ?
Mon May 16, 2005 9:49 am |
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swiy agrees w/ all said avec the grease lab grade etc..
The heavy NP's was a new thing for swiy. aka-(DCM) very problematic as swiy has just learn'd it don't act as most the NP's swiy has used.
PTFE, stopcocks are great. make sure one has enuff O-rings for the size of that PTFE stopcock as well them there things ware out fast. |
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