Yttrium2
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Chemical Resistance of Stoppers
Which bungs / Stoppers are best?
Which have the most chemical Resistance?
Or, which material stopper is used for what?
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DavidJR
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Ground glass stoppers are best.
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Morgan
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Well I bought a bunch of rubber stoppers with no holes, one, and two holes and over time they started to sweat an oily substance and aside from that
they are now hard. Maybe putting them in bags and keeping them in the garage in summer did it.
So for some things these silicone stoppers are better like higher temperatures but they aren't good for some chemicals. I don't like the way the black
rubber stoppers smell, thus I kept them outside. And it's a hassle if you don't have the right size so I forced myself to buy a bunch of sizes once
again. Here's some larger sizes of the silicone stoppers atop my freezer in the garage. These stoppers smell too though, but maybe over time the odor
will fade.
https://www.ebay.com/itm/80pc-1-16-3-4-High-Temp-Silicone-Ru...
 
[Edited on 18-3-2018 by Morgan]
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Magpie
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I usually buy EPDM. For best chemical and heat resistance I use Viton.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Akhil jain
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It is best to use rubber stoppers since holes can be dig in it ,they are air tight and cheap.
But if you are making nitric acid you can't use rubber stoppers since nitric acid attacks rubber. In this preparation whole apparatus is made of glass
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BromicAcid
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Once upon a time, cork stoppers were about all that was available. Older literature however is able to use them for many applications by treating
them with the appropriate compound (waterglass, shellac, bitumen, etc). On the plus side they are cheap.
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metalresearcher
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Quote: Originally posted by Akhil jain  | It is best to use rubber stoppers since holes can be dig in it ,they are air tight and cheap.
But if you are making nitric acid you can't use rubber stoppers since nitric acid attacks rubber. In this preparation whole apparatus is made of glass
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However, this is a tedious job. Same with silicone stoppers. Simply using a cordless drill is not an option as the hole drilled jumps back as it is
too elastic. Even when the drill bit is 2mm larger than the diameter of the tube to be used.
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Akhil jain
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It is not a tedious job to make holes in rubber stoppers
If you have a cork borer it is very easy if you have a drill it's still easy. You can even drill two holes and pass two delivery tubes in it . Use
rubber stoppers if you don't want your gases to leak out . It is easy to work with rubber stoppers than glass ones
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Magpie
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I use one of those “cork borers” to bore holes in the rubber.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Akhil jain
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| Quote: Originally posted by Morgan | Well I bought a bunch of rubber stoppers with no holes, one, and two holes and over time they started to sweat an oily substance and aside from that
they are now hard. Maybe putting them in bags and keeping them in the garage in summer did it.
So for some things these silicone stoppers are better like higher temperatures but they aren't good for some chemicals. I don't like the way the black
rubber stoppers smell, thus I kept them outside. And it's a hassle if you don't have the right size so I forced myself to buy a bunch of sizes once
again. Here's some larger sizes of the silicone stoppers atop my freezer in the gara
[Edited on 18-3-2018 by Morgan] |
Can I use silicon stoppers for making nitric acid . Won't they be attacked by fuming HNO3
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Sulaiman
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For boring holes through corks and red rubber bungs, I have similar to these
https://www.ebay.co.uk/itm/Ajax-Scientific-6-Piece-Brass-Cor...
but I rarely use them.
There are matching sharpeners https://www.ebay.co.uk/itm/RVFM-Cork-Borer-Sharpener/1223699...
CAUTION : Hobby Chemist, not Professional or even Amateur
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Magpie
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I use my borers all the time. Thanks Sulaiman for the link to the sharpeners, I just bought one off Amazon.
The single most important condition for a successful synthesis is good mixing - Nicodem
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symboom
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Could rubber stoppers be coated in teflon spray to proteck them from corrosive compounds suchbas rubber desolving solvents and strong acids
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phlogiston
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| Quote: Originally posted by metalresearcher |
However, this is a tedious job. Same with silicone stoppers. Simply using a cordless drill is not an option as the hole drilled jumps back as it is
too elastic. Even when the drill bit is 2mm larger than the diameter of the tube to be used. |
Freeze the rubber prior to drilling.
Ben Krasnow (Applied Science) has a video on machining frozen rubber with a cnc router.
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"If a rocket goes up, who cares where it comes down, that's not my concern said Wernher von Braun" - Tom Lehrer |
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Yttrium2
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| Quote: Originally posted by metalresearcher | | Quote: Originally posted by Akhil jain | It is best to use rubber stoppers since holes can be dig in it ,they are air tight and cheap.
But if you are making nitric acid you can't use rubber stoppers since nitric acid attacks rubber. In this preparation whole apparatus is made of glass
|
However, this is a tedious job. Same with silicone stoppers. Simply using a cordless drill is not an option as the hole drilled jumps back as it is
too elastic. Even when the drill bit is 2mm larger than the diameter of the tube to be used. |
They have drill bits for rubber stopper
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Sulaiman
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So do you bear "the mark of the chemist" ?
CAUTION : Hobby Chemist, not Professional or even Amateur
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Magpie
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No marks except on my wood bench. I now place a piece of sacrificial wood under the stopper when boring. I also wear leather gloves.
The single most important condition for a successful synthesis is good mixing - Nicodem
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Morgan
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I saw this but just wonder how a brad point drill bit would work?
How to drill a hole into a rubber stopper
https://www.youtube.com/watch?v=S9Webmd9Jvw
https://www.toolstoday.com/g-22-the-brad-point-boring-bit
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LearnedAmateur
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I use orange rubber stoppers mostly, got a couple of glass ones too which are obviously fine for the majority of applications, but rubber is attacked
by a lot of solvents over time. I’ve noticed that when stoppering a flask containing ethanol, isopropanol, toluene etc. They tend to swell and
‘wet’ bits will flake off. I’ve ended up having these bits floating around in the mixture/solvent when they’re removed before.
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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XeonTheMGPony
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I've applied a gentle layer of silicon grease then wrapped in teflon tape the stoppers when I had to use them for harsh reactions and it seems to have
don the job on most of them for most of the time, rubber is a crap material IMO hardens over time, can fuse to the glass in certain conditions, cheap
rubbers smell bad.
They had their time, I prefer to use glass gas inlets and such failing that chemically treated cork wold be preferable to rubber!
I never used silicon befor but knowing the material I'd say it'd be better.
Then there is machined teflon stoppers one can get.
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