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Author: Subject: Rubber stoppers
rivetboi
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biggrin.gif posted on 29-2-2012 at 18:20
Rubber stoppers


I am looking to acquire an inexpensive assortment of rubber stoppers. Can anybody suggest a good source?

[Edited on 1-3-2012 by ScienceSquirrel]
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TheChemINC
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[*] posted on 29-2-2012 at 18:44


ebay
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zoombafu
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[*] posted on 29-2-2012 at 19:59


at amazon (I've bought them from here in the past)
<a target="_blank" href="http://www.amazon.com/mn/search/?_encoding=UTF8&x=0&tag=thehomche0e-20&linkCode=ur2&y=0&camp=1789&creative=390957&fi eld-keywords=assorted%20rubber%20stoppers&url=search-alias%3Daps">rubber stoppers</a><img src="https://www.assoc-amazon.com/e/ir?t=thehomche0e-20&l=ur2&o=1" width="1" height="1" border="0" alt="" style="border:none !important; margin:0px !important;" />

as well as at elemental scientific
rubber stoppers #2




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MyNameIsUnnecessarilyLong
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[*] posted on 29-2-2012 at 20:08


McMaster Carr has cheap stoppers in bulk
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bquirky
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[*] posted on 1-3-2012 at 07:31


in Australia a chain called "Clark rubber" stocks a full range of ruber and cork bungs/stoppers from small to huge
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AirCowPeaCock
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[*] posted on 1-3-2012 at 07:54


look at united nuclear, they have a stopper assortment kit.
http://unitednuclear.com/index.php?main_page=product_info&am...

44 stoppers for $15




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Dr.Bob
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[*] posted on 1-3-2012 at 10:42


Quote: Originally posted by AirCowPeaCock  
look at united nuclear, they have a stopper assortment kit.
http://unitednuclear.com/index.php?main_page=product_info&am...

44 stoppers for $15


That is cheaper than I can buy them from our "preferred" lab supply house at my workplace's "special discount"... :-)

I might try to order some from there.
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Hexavalent
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[*] posted on 3-3-2012 at 07:47


What differences in quality do you get between cheap and expensive rubber stoppers? IMO, it is worthwile, albeit more expensive, to get slightly more expensive ones that will last longer. Ground glass flasks and stoppers are the best, though.



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zoombafu
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[*] posted on 3-3-2012 at 11:47


Quote: Originally posted by Hexavalent  
What differences in quality do you get between cheap and expensive rubber stoppers? IMO, it is worthwile, albeit more expensive, to get slightly more expensive ones that will last longer. Ground glass flasks and stoppers are the best, though.


I'm pretty sure that rubber stoppers are all the same. I've bought many of them from various suppliers at various prices, they are all the same.




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rivetboi
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[*] posted on 16-3-2012 at 15:38


Thank you all for your help! I placed an order with United Nuclear and got two of the small size assortments the same day I found a supplier that would eventually send me 40 #6 and #8 stoppers in EPDM and Silicone as free samples in my capacity as an engineer. I guess you can never have too many stoppers, eh?

Followup: I bought a 150mm Buchner from Dr. Bob. Any ideas where i can get a stopper for a 1L Erlenmyer that will fit this thing?

Thanks again, all!
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[*] posted on 16-3-2012 at 17:17


I can also get rubber and cork stoppers at Ace Hardware. But I'm not sure if the rubber is of the same specification as that for lab use. And the corks are crappy.

[Edited on 17-3-2012 by Magpie]




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zoombafu
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[*] posted on 16-3-2012 at 18:57


Quote: Originally posted by rivetboi  

Followup: I bought a 150mm Buchner from Dr. Bob. Any ideas where i can get a stopper for a 1L Erlenmyer that will fit this thing?


I just used an electric drill and drilled a hole through my rubber stopper, because I couldn't find a stopper that would fit my funnel and flask. Works perfectly for me




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[*] posted on 16-3-2012 at 20:18


Quote: Originally posted by zoombafu  

I just used an electric drill and drilled a hole through my rubber stopper, because I couldn't find a stopper that would fit my funnel and flask. Works perfectly for me


Or if you own a drill press, arbor press, pneumatic press, or even a vice you can bore a much cleaner hole in stoppers by using a piece of tubing with a sharp chamfer on one end and press it through.
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Lambda-Eyde
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[*] posted on 16-3-2012 at 22:40


Quote: Originally posted by zoombafu  

I just used an electric drill and drilled a hole through my rubber stopper, because I couldn't find a stopper that would fit my funnel and flask. Works perfectly for me

Or you can just abandon the whole idea that rubber stoppers should be used in conjunction with filter funnels. Rubber gaskets were invented for a reason:



With one of these beauties you avoid the problem of half-assed solutions and you'll never break the stem on your expensive fritted funnels (and you won't stab yourself while trying to).




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[*] posted on 17-3-2012 at 06:37


another handy hit when drilling holes in rubber first freeze the rubber it makes drilling the hole much essayer
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Morgan
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[*] posted on 17-3-2012 at 17:59


Has anyone tried making silicone rubber stoppers? Seems like an interesting project.
I bought a giant set of solid, one and two-holed rubber stoppers because I got so tired of not having the right size when I needed it.
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Arthur Dent
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[*] posted on 19-3-2012 at 03:27


Quote: Originally posted by Magpie  
I can also get rubber and cork stoppers at Ace Hardware. But I'm not sure if the rubber is of the same specification as that for lab use. And the corks are crappy.

[Edited on 17-3-2012 by Magpie]


I like Ace Hardware, it's the only place that still carries a nice selection of solvents and pure NaOH crystals.

The stoppers they sell (beige rubber) are similar to the stoppers I bought at the lab supply shop. These are aimed at home distillers, beer and wine makers.

I've used these stoppers in various reactions, and they seem quite resistant, although chlorine and HCl gas tend to discolor the exposed surface to a light brown/tan. The lab grade stoppers react the same way.

I like the beige stoppers because the rubber is softer and fits more tightly than the green stoppers, whose rubber seems to be harder (I can drill easily through them without freezing). The black rubber stoppers seems to be the hardest of the bunch.

One trick I use is to put a small dab of vacuum grease on the stem of a funnel before pushing it through the stopper's hole, while gently twisting, to prevent too much stress on the glass.

And you're right, Ace's cork stoppers are pathetic, pale bleached cork that's so brittle it splits in half if you try to drill through it. Surprisingly, the dollar store cork srtoppers seem to be of higher quality, and available in all the sizes I need.

Robert






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