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Saerynide
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Quote: Originally posted by peach  | | Although it's never broken any glass, I am always annoyed when a solution thickens and the stir bar breaks free. It start swirling round and round
like a coaster at the fair and, the motor free wheels and starts vibrating, and the glass tries to do the washing machine dance.
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Omg. I cant agree with that one more! Ive had a stir bar in a scintillation vial of a viscous pre-polymer mixture. The vial started to do the
resonating washing machine thing when i wasnt watching and before i knew it, it unscrewed the cap and then flung my sample everywhere  I couldnt even scoop up my sample to re-purify since it for bio stuff 
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peach
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In response to.... MAGPIE
| Quote: | | It seems like you can't even buy a decent glass buret for under $50-$100 on the open market. I'm sure I didn't pay over $25 for mine on eBay but that
was some time ago. |
Quality certainly does cost when it comes to class A and new. The guys buying that stuff will get very picky as well - for example, they'll make sure
their solutions are actually at 20C (or the specified temperature), density is another. If it's a high resolution balance, aw... then you're in
trouble.  You'll have to redecorate to make it happy.
If you're into high accuracy work, there is a great PDF on google that goes into a lot of detail about the standards, films on the glass and so on.
I had a look for you but couldn't easily find it. If you google 'glassware to dispense to contain' you may be able to find it and the related
documents. The one I'm thinking of is pages long and discusses the difference between ISO / BS and other standards.
| Quote: |
I've ruined quite a few of the cheaper Keck clips, usually by overheating. I bought some Teflon clips that are quite beefy and a lot better, and will
take a higher temperature too. But they are quite spendy. |
I am beginning to dislike standard keck clips. They're polyacetal.
They do indeed melt at too low of a temperature to be reliable - 125C from memory. That is well within the region of a normal distillation, meaning
columns / flasks / heads and condensers need care when using them, because it is easily possible to soften / warp / melt the clip and have the glass
fall apart.
In fact, I've just finished cleaning one off my vigruex after it did that trick.
Polyacetal is used because it is is reasonably resistant to chemical attack.
It is not, however, resistant to acid hydrolysis. This means if you're working with strong acids you have potential problems.
Acid gases are even worse.
Worse again, the polymer is particularly sensitive to chlorine donors. Meaning, hydrogen chloride is not it's friend at all.
I can promise you, I have thrown out a handful of clips that have literally fallen apart in the presence of tiny amounts of the gas escaping through
Krytox greased QuickFit tapers.
It's worse than them melting, because there's no warning sign that they're about to go. They'll be absolutely fine, then a funnel will fall off and
the clip with be split.
They can't handle it, at all.
There is a guy in the US, I think it's Expediglass on eBay, selling polyacetals for a lot less than united glass, who sell Schott Duran's clips. I
have tried some of those. They're from China, because the envelope says so. They look kind of cheap in terms of them being faintly pigmented, but they
perform just as well for a lot less money.
Schott Duran, QuickFit and Chemglass (they call it Durite - marketing balls) all use polyacetal as their standard for keck clips.
Stainless.... yes! Much higher temperature. However, stainless, even Innox, does start to corrode around the reactive gases. Only monel will withstand
those outside of the platinums and it's not a standard alloy for most people (it's nickel based, rather than iron, and expensive).
If you're after the springs, Chemglass do them. But they're $18 for 6 tiny ones I think. You may be better eBaying those, as quite a lot of odd
stainless or titanium springs and bolts appear on there for the engineering folk and guys doing their super bikes up.
I have a small number of them. They hold the receiving test tubes on the end of my short path. But... the tubes also take keck clips. And only the
receiver tubes have the spikes for using them. The rest of the glass doesn't.
The only immediate benefit I see to springs is that they add a layer of insurance against the glass bursting, by letting the joints open if there's a
sudden pressure rise. Other than that, they're fiddly and easy to loose.
PTFE is seemingly the best. The 250C temperature limit is dead on for what's needed during most organic work. The chemical resistance is second to
none. They may swell with extreme solvent exposure, as PTFE does this around halogenated solvents.
But, at a whopping £7 PER CLIP, they certainly are NOT cheap!
The only person I've seen on here using them is Klute, who also has the tapered and screw together glass - again, the only person I've seen on here
with it. I have two of the G thread to B taper PTFE adaptors, but none of that really detailed gear. Sigma sell it as System 45 with the Ace brand on
it. There is also Rotaviss. I think System 45 is produced by ndstechnologiesinc.com. It's all over their page, they reference you to Sigma and I've
had a chat with them - that's where my adaptors came from.
I think you can rest assured the PTFE clips weren't a waste.
I have wondered about making my own. The standard ones at the moment are moulded, which is very expensive to do with PTFE. I was thinking it'd be
cheaper to buy a bar of it and simply cut them out. If I do, and they work, I'll stick some up on here for others to grab.
[Edited on 3-1-2011 by peach]
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UnintentionalChaos
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| Quote: Originally posted by peach |
I have wondered about making my own. The standard ones at the moment are moulded, which is very expensive to do with PTFE. I was thinking it's be
cheaper to buy a bar of it and simply cut them out. If I do, and they work, I'll stick some up on here for others to grab. |
I'm under the impression that the PTFE clips are actually steel with a PTFE coating.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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peach
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They are.
At least the ones I've seen.
Moulding PTFE like that is not easy, hence the price - pure PTFE is A LOT cheaper than that.
If it can be done with polyacetal, I expect it could also be done with solid PTFE.
They may be using a steel wire due to the moulding process. A lot of moulded PTFE is 'grainy' and more like billions of bits of PTFE dust stuck
together; sintered (it's not a thermoformable plastic so it can't be injection moulded or heat formed, which is it's main drawback and why things like
PFA, FEP and ETFE came about). This is why I can stain PTFE stir bars black with precipitate - it's getting stuck in the grain structure.
It's moulded isostatically, where a lot of pressure is applied from each direction and the mould is then warmed up to squeeze and melt the grains
together - so I guess it's a bit like a frit in that sense.
That's 'grainy'ness would not be good if that's all you were relying on for support.
Virgin, solid bars of PTFE don't have this, as they come fresh out of the polymerization.
[Edited on 3-1-2011 by peach]
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peach
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| Quote: |
I can buy metal ones on ebay here ($9USD!! each ), but I've never seen the PTFE
ones. Just did a bit of research, looks like they're made for quickfit. Do you know offhand if quickfit sizes are compatible with US standard taper?
I think the answer is yes, but I'm not entirely sure. |
I've used clips from the US on my QuickFit in the UK (QuickFit is a trademark of SciLabWare, and it's blown in Staffordshire in the UK - I have actually had a chat with SciLabWare about this and, if you check the wiki on QuickFit, I've added all the different names the glass has been
blown under since they formed and the company merged with others). The glass had always been trademarked QuickFit, but the company name has
changed quite a few times.
I wanted to make it clear in that article that quickfit does not mean 'tapered glass'. QuickFit is an actual trademark and sold by a specific company.
Works fine, there's no difference. 
The only important thing is the diameter, and that's the same for the UK and US tapers - only the length is different.
In the UK, the length is always the same for each B number. In the US, people like Chemglass will change the lengths a bit for each. There is more
variation in the clamping between manufacturers and regardless of region based on how thick the ring section is around the top of the female joint.
Regardless, they all clamp fine for glass and chemistry (tried Chemglass, Kontes, LIG, QuickFit and custom blown; there's no major difference).
I have found a couple of places doing the PTFE clips. One of them was some stoner's place selling pipes and bongs made with lab tapers on them, but
they're all about the same price... £7 a clip.
Use sparingly.
It's probably a good thing, as clipping all of your glass means that bitch is going to burst (explosively / in flames / with cuts / burns) if
something goes wrong.
Stoppers and such don't really need tightly clipping.
It's better then open and make a mess than the entire thing goes up.
[Edited on 3-1-2011 by peach]
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The WiZard is In
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| Quote: Originally posted by kuro96inlaila | I don't know what to say,am I cursed or something?
Everytime I use an evaporating dish,sure it will broke!
Everytime............ |
Buy one made of Corning Vycor® glass (Code No. 7913 glass,
96% silica). Corning years ago demonstrated it by pouring molten
lead into a Vycor dish sitting on a block of ice. My old (not dated)
Corning catalog only lists two sizes 45ml and 100ml.
Krell metal dobe better, however, the ship carrying the last
shipment of the metal from Altir-4 was forced down on the
planet Dubious-7 and has hot been heard from since.
http://en.wikipedia.org/wiki/Text
PS - Never/ever put one of them side arm vacuum flasks over a burner.
I wouldn't put mine on a hot plate.
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peach
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Do you know how the price of vycor compares to genuine fused quartz?
For the really slippery fingered, there is PFA 'glassware'.
Expensive is perhaps putting it mildly ($122 for a 100ml single necked flask, $473 if you want the luxury of three necks).
I think it must be used for hydrofluoric work and things like that.
[Edited on 4-1-2011 by peach]
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The WiZard is In
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Not oft hand... however, in my out of date Corning catalogue
Vycor is 10-12X the price of Pyrex. In my 1971 Lab Glass Inc.
catalogue the only quarts parts listed ground glass joints
(complete sets) the 45/50 is 5X more expensive then Pyrex.
I suffer from the feeling backed up by NO info - that for more
complex glassware there will be a greater difference on the plus side.
Nothing a little time w/ Google couldn't answer.....
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peach
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I'd love a whole set made out of fused Q, I know you can get it custom blown - but that's a lottery win scenario.
About the only thing I think I'd need from it are some bits of tube for lining furnaces - that's probably a bit more realistic.
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Lambda-Eyde
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http://www.technicalglass.com/
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The WiZard is In
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Curious do be I... they give the permeability for —
He, H2, Deuterium and Ne. Wonder I what quartz's
permeability to I2 — which it is claimed can migrate through
common glass is?
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peach
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Awwwww nice!
It may be a slow process, but I've never had any problems, or signs, of iodine getting into the glassware, let alone through it - and I have used
extremely concentrated solutions of it (as it's perfectly fine to buy loads of it in England  ).
The other materials they've listed are for the physicist.
Quartz is quite often used for windows and apertures on ultra high vacuum equipment or weird furnaces.
A lot of physics involves deep UV to gamma spectrum radiation.
Normal glass is too opaque for that. I contacted Heraeus at one point about extreme UV lamps and they said even the quartz is annoying, as it has an
opaque region between the end of UV and start of gamma.
Of coarse, many of these lamps are deuterium filled and have a quartz window. Helium, hydrogen and the other light gases are the main problems for
ultra high vacuum, as they are a bugger to get rid of - e.g. hydrogen is often trapped in steels, and then bleeds out.
[Edited on 5-1-2011 by peach]
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The WiZard is In
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| Quote: Originally posted by peach | Awwwww nice!
It may be a slow process, but I've never had any problems, or signs, of iodine getting into the glassware, let alone through it - and I have used
extremely concentrated solutions of it (as it's perfectly fine to buy loads of it in England ). |
Patience Grasshopper.
67. The permeability of glass to iodine and bromine vapours.
James Brierley Firth. Jour. Chem. Soc. Lond., 117, 1602-3 (1920).
—Iodine and bromine do not diffuse through glass under ordinary
experimental conditions. Only in extreme cases is there a
possibility of such diffusion. After a period of nine and one-half
years, iodine was found to have passed through a glass bulb 0.208
mm. thick. The bulb was heated to 360 °C for 100 days during the
experiment. In this experiment the bulb was placed in a large tube
and both tube and bulb evacuated. In another case, in which
iodine was found to pass through 0.211 mm. of glass, there was a
vacuum outside of the bulb and atmospheric pressure inside. here
was no evidence of bromine passing through a similar thickness of
glass after nine and one-half years. J. L. C.
http://tinyurl.com/33ct5wb
Possible others — I stopped looking after finding the above. /djh/
-------
Some years back Nature [England] had a series on long term
experiments, the one I remember was tar that every
70(?) years a drop fell from its funnel like container.
/djh/
-----
There are more things in heaven and earth, Horatio,
Than are dreamt of in your philosophy
[Edited on 5-1-2011 by The WiZard is In]
[Edited on 5-1-2011 by The WiZard is In]
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smuv
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This is your drige
*sobs* I broke a 3000L RB flask today. It was full of nearly 100g of freshly crystallized paracetamol.
It all started when I put the flask down to get a spatula, I just layed it on its side because I didn't have a cork ring on hand...I noticed across
the room it was rolling off of the table. I shouted NOOOOOOOOOOOOO and ran across the room, throwing the spatula and disposable pipette (another
casualty) in my hand. I didn't make it in time. You can't save 'em all.
Oh well, nothing gold can stay.
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psychokinetic
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3000L?
I sure how you meant mL, or else there are pictures necessary 
“If Edison had a needle to find in a haystack, he would proceed at once with the diligence of the bee to examine straw after straw until he found
the object of his search.
I was a sorry witness of such doings, knowing that a little theory and calculation would have saved him ninety per cent of his labor.”
-Tesla
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UnintentionalChaos
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It can go with Peach's 600m vigreux column. We're working on a full distillation setup for the Atlantic ocean.
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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smuv
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lol. Peach, lets do it. Anyone got a heating mantle for this?
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User
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Lol , that happened to me 2 once (although not with a 3000L flask).
I use empty tape rolls as stands for rbf's
As for other stupidity:
It was a hot summer day and I needed some alcohol
So i filled up my 2 litre rbf with denaturated spirit.
Put on a vigreux and stoppered it to cover it from dust.
Went to a store etc etc, came back....
This was no pretty sight, the vigreux had launched itself apparently.
Probably because of to much pressure from the vaporizing alcohol.
another 200mm vigreux shattered to pieces, these things are too expensive for foolish actions like mine.
I thought about blaiming the cat , no this was just stupid.
[Edited on 20-1-2011 by User]
What a fine day for chemistry this is.
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The WiZard is In
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| Quote: Originally posted by smuv | | *sobs* I broke a 3000L RB flask today. It was full of nearly 100g of freshly crystallized paracetamol. |
Amateur.
Theodor Grewer
Thermal Hazards of Chemical Reactions
Industrial Safety Series Volume 4
Elsevier
1994
 
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Saerynide
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Had my first implosion today... I put a rack of my samples in a supermassive vacuum dessicator, hooked up the vacuum pump and went off to lunch.
When I came back to check on my samples, I saw what looked like really nice crystals where my samples were. Then I realized they were no crystals,
but glass shards. I thought "what?? My vials imploded?? Thats not even physically possible!!" Then I saw the gaping hole and giant crack that almost
split the 18 inch lid in half... The damn thing mustve had a hairline crack that no one noticed all this time
I am soooo thankful I put it in the fume hood and pulled the sash down all the way before I left... I'd hate to have my team cut up by exploding
shards of 1/4 inch thick glass :S Im also glad it happened over lunch when the lab was empty. Woulda scared the living shit out of everyone I had even thought of wrapping it in duct tape before, but since no one had all
these years before me, I decided itwould be over kil and they would look at me funny...
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The WiZard is In
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| Quote: Originally posted by Saerynide |
I had even thought of wrapping it in duct tape before, but since no one had all these years before me, I decided itwould be over kil and they would
look at me funny... |
Me thinks the chance of anyone doing this is ....
Glass blowers after they anneal their work — put in between two
polarizers and look for stress. Would work for cracks
me thinks.
djh
----
Cunning, Care and Sheer Luck Save Rare Map
NY Times 17i11
White lines were visible where the map had ripped, the brighter inner fabrics of the
paper standing out from the stained surface. Mr. Derow visited Argosy Book Store on
the Upper East Side and bought a handful of obscure old books - among them, for
example, "The Select Dialogues of Lucian, to Which Is Added, a New Literal
Translation in Latin, With Notes in English," from 1804 - that were printed on cloth
paper, like the map, and not wood pulp.
He performed on them a technique that should chill the blood of any author,
wondering where his books will be in 200 years: he baked them in his kitchen stove
and boiled them in water. He painted the resulting brackish stew onto the white
lines, matching them to the rest of the map.
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hissingnoise
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The cat? You can't just let any animal into your lab!
If you want a pet in the lab - get a lab-rador . . .
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peach
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<iframe sandbox title="YouTube video player" class="youtube-player" type="text/html" width="640" height="390"
src="http://www.youtube.com/embed/FkXwNQwrxZ4" frameborder="0" allowFullScreen></iframe>
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Saerynide
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Wow that is so neat! I cant believe I didnt know about this all this time
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Sedit
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Yeh LCD screens work by bending polarized light thru liquid crystals hence you need a series of Filters to cause the floresent tubes behind the screen
to turn into an array of colors.
Floresent tube->Filter->Liquid crystals---light bent-->Filter= Color
Knowledge is useless to useless people...
"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the
fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story
before."~Maynard James Keenan
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