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peach
Bon Vivant
Posts: 1428
Registered: 14-11-2008
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Mood: No Mood
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I don't bother to measure it out precisely, I use disposable 3ml pipettes - which I then rinse out and reuse. They're available in hundred+ bags for a
few pounds and are exceptionally handy.
To clean sinters, I stand the item up in a jam jar (or something similar), add a squirt or two of 98% sulphuric, then a squirt of 35% peroxide, give
them a swirl and let it stand.
I use two different pipettes for each of the components, and I keep the peroxide in the freezer. That not only helps prolong it's lifespan, but also
means that it takes a little longer for the process to get started.
It does start, quite quickly. The mixture rapidly warms up and begins to effervesce. Things that look clean almost immediately begin turning brown,
and possibly even black, if there is any trace of colourless organic material there. The mixture begins to sound like a freshly opened bottle of coke
as it fizzes away.
With coarse sinters, the mixture will usually flow through them under gravity alone, within a minute or three. I simply remove the glassware from the
jar and pour the mixture back through two or three times. For medium to fine sinters, particularly those that are clogged up, applying some very
gentle suction to draw it into the sinter will help. I then leave it to get on with it's own thing rather than bothering to constantly cycle it.
You something may end up with something exploding using this method. I do not use hard suction and cycle it, because the shock of the hot mixture
running through and then the sinter drying out is that kind of thing that could help something detonate (this is the same scenario that ended with a
student being sprayed with bits of glass when a filter under vacuum exploded). I usually leave the glass to sit for hours or overnight, allowing the
mixture to chew away at the dirt and decompose, and then rinse over and over with water to remove it. I tend to do the first rinse by gravity if
possible, in an attempt to gently rinse anything potentially explosive out of the sinter and into a solution.
There is no point mixing up a hundred mls of it, as it only requires about 3-9ml to clean a sinter well. It decomposes so rapidly the entire lot will
be dilute sulphuric by the next day, so there's no point storing it either. Even if you plan to use it immediately and end up needing more, it's
better to mix it as it's used so it's always fresh when put into use.
I have tried the persulphate in place of peroxide method (NoChromix), but prefer the peroxide by a long way.
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Hexavalent
International Hazard
Posts: 1564
Registered: 29-12-2011
Location: Wales, UK
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Thanks for your input. And a word of warning for beginners - if you are new to chemistry, it is probably not a good idea to start your adventure into
the world of science with such materials. They are hideously corrosive, toxic, produce toxic and irritating fumes and require full PPE including heavy
nitrile or neoprene gloves, a chemically impervious apron or hellova good lab coat, chemical splash goggles and a face shield.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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Dariusrussell
Hazard to Self
Posts: 70
Registered: 27-6-2013
Location: Southie
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Mood: Organometallics
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Glassware cleaning?
I recently got a hold of a used corning organic glassware set and two of the pieces are a bit dirty. One is a 125 mL RBF and the other is the vacuum
takeoff.
I've read This Topic
and found a plethora of things to try. I already tried warm water and soap, Ethanol/Methanol, and acetone. Im guessing they havent been used in 20+
years so the stains are caked on pretty well.
Does anyone have a good easy next thing to try (ie Fentons, Piranha?)
The substance is white and powdery so not much help in identifying it.
In the pictures there is some water and condensation, if needed I can take more pictures once dry.
<img src="http://i1318.photobucket.com/albums/t649/Darius_RK/d8f12a7d-d926-4863-b2e2-cfb84bfabfcf_zps4964a3c5.jpg" width="600" />
<img src="http://i1318.photobucket.com/albums/t649/Darius_RK/IMG_3217_zpse215b0af.jpg" width="600" />
<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: reduced
image size(s)]
[Edited on 7/26/13 by bfesser]
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crazyboy
Hazard to Others
Posts: 436
Registered: 31-1-2008
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Mood: Marginally insane
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In my experience a cup of sand with some water or cleaning fluid works well. Swish that around in the round bottom for a while and that works pretty
well. Failing that some concentrated sulfuric acid with a bit of water usually works as well.
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Rich_Insane
Hazard to Others
Posts: 371
Registered: 24-4-2009
Location: Portland, Oregon
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Mood: alive
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Try a concentrated NaOH bath. Use boiling water for best results. Be careful, over time, this treatment can weaken some types of glass... But I find
that a warm base bath works well. If that fails, try sulfuric acid. Of course, you should try a couple different solvents before resorting to more
corrosive agents. Acetone is good for cleaning (it evaporates off pretty quickly). Dichloromethane might be good too. I've used those two solvents in
the past to remove organic residue in glassware.
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bfesser
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Threads Merged
26-7-2013 at 14:57 |
bfesser
Resident Wikipedian
Posts: 2114
Registered: 29-1-2008
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Mood: No Mood
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So you searched for and found an existing thread, but
in defiance of all logic and perhaps even common sense, started a new one instead? I appreciate that you've done your research, but in the future,
please reply to existing threads on your intended topic rather than starting new ones (if applicable). Thank you.
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