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Yttrium2
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Heavy wall glass
Does heavy wall borosilicate glass crack easier due to temperatute changes versus borosilicate glass that isn't heavy walled?
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Texium
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Thread Moved
24-3-2018 at 17:37 |
Chemetix
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In general yes!
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LearnedAmateur
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Yes, glass is a mild insulator (I’d say between that of plastics and metals) so it takes longer for heat exchange between the nearest and furthest
surface. This basically means that there will be a higher temperature gradient between the two surfaces with thicker walls, and that gradient is what
causes glass to crack because of thermal stress. If you treat heavy glass like any other piece though, you should be fine - just don’t go
immediately to hitting it with a direct flame, use a gauze or at least heat outside of the flame for a minute or two first.
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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RawWork
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According to Handbook of Inorganic Chemicals: "Quartz is an excellent insulator. It does not break under temperature changes because of its low
coefficient of expansion. Fused quartz transmits ultraviolet light."
So use SiO2 glass. I doubt that any other glass has lower coefficient of thermal expansion. That's reason which determines will something break.
Unlike LearneAmateur said.
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unionised
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Quartz is a great insulator- for electricity.
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Tsjerk
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But starting to make thick wall glassware out of quartz seems a bit pricey.
Usually thick walled borosilicate is not meant to be heated anyway.
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Morgan
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It's too bad someone couldn't make something intermediate between borosilicate and quartz without the high price, that is something more heat
resistant - say add just a little more SiO2 to a boro mix if possible.
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Yttrium2
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Heavy wall is used for vaccuum applications, correct?
If it has the same thermal coefficient of expansion, and is borosilicate glass, why isn't it just as resistant to cracking as thinner walled material.
Why is everyone going off to talk about quarts?
(Sorry I posted this here. Something happened where I saw only certian forum sections po up and I figured I was banned)
[Edited on 3/25/2018 by Yttrium2]
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unionised
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Quote: Originally posted by Yttrium2  | Heavy wall is used for vaccuum applications, correct?
If it has the same thermal coefficient of expansion, and is borosilicate glass, why isn't it just as resistant to cracking as thinner walled material.
Why is everyone going off to talk about quarts? |
Thin walled glass heats more evenly so it's less likely to crack when heated. Nobody but you wis is talking about quarts.
Quartz is stronger and has a lower thermal expansion so it's better for thick walled stuff.
It's much more expensive.
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RawWork
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Yes, "low", not "same" (even) coefficient. Because Si is more common element than B. Also I believe Na, Ca and others could be somehow removed from
glass as they are minor. Or why not make SiO2 glass? There are quartz heaters where I see red hot filament of iron and quartz around it. Very
resistant to temperature.
It's true that thicker something is the more resistant to pressure or temperature changes it is. That's why lead glass is used in CRT.
Why not just use CRT? They are now almost free. They are resistant to pressure and temperature changes enough.
https://www.youtube.com/watch?v=qp6tNaUvfNI
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unionised
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They do make silica glass. It's refereed to as fused quartz, and it's what people have been talking about here.
The problem is that it's expensive- because it is difficult to work with.
It is not true that thicker glass is more resistant to temperature changes- You have got it backwards. Thick glass is more likely to crack with
thermal shock.
Lead glass is a good electrical insulator which helps, but the real reason they used it in CRTs was to block Xrays.
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Yttrium2
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Ultimately, I'm wondering which distillation kit to go with.
There is a seller on Amazon called dinglab, but it's heavy walled glass and a few bucks extra, however everyone is ranting and raving about there kit.
Except the distillation adapter, I guess it wasn't made to well -- the plastic piece
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Yttrium2
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Ahhhh I'm having a hard time deciding which distillation apparatus is best. I'm thinking one with a 3 way adapter that has a seperate thermometer
attachment. Can someone provide information on the chinese distillation kits? Are they virtually all the same? Cause I've noticed subtle differences
with the 3 way distillation adapter, and how the thermometer comes hooked up. Is there a difference in packaging? Which ones should I go with/avoid.
also, can someone provide information as to when and why heavy wall glass is desireable? Does it greatly increase risk of a flask cracking, or not so
much with the borosilicate glass?
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Yttrium2
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Maybe I should just get a 250ml erlenmeyer, a stopper, and a couple pieces of very long glass tubing... It would save a bit of money, and would likely
do just as good of a job for most applications (I'm guessing)
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aga
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Just get the cheap stuff - works fine for everything i've tried.
The two events that destroy my glassware are Shipping and Cleaning (mostly cleaning).
Never lost a single glass item during an actual experiment.
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unionised
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If you plan to use some sort of heating bath (and you should) then thick walled stuff should be fine.
I haven't seen the kit you are talking about, so I can't comment.
Perhaps others have.
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Yttrium2
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the cheap stuff as in a single flask with a really long glass tube, or the cheap stuff such as the cheap distillation apparatus? Ehh
was thinking of getting the cheapish one with the nice 3 way distillation adapter that has the thermometer and adapter as a separate piece from the 3
way distillation adapter. I can get that and a claisen adapter (so I can do steam distillation/maybe more) for around 36$ with shipping.
I've gone through a few kits during my time, its nice to see the prices dropping especially because of the way I go through kits 
[Edited on 3/25/2018 by Yttrium2]
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aga
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What time ?
Not seen you post anything about what you've done.
Photos are always nice.
Edit:
The cheap stuff i was referring to was a 200 or 300 ml Liebig condenser and a disty head - the one that is straight with an angled arm, all
ground-glass 24/29 joints.
[Edited on 25-3-2018 by aga]
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Sulaiman
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I agree with aga that damage during shipping/storage/cleaning/drying is much more likely than damage during an experiment.
So a little care during heating and cooling using heavy wall flasks may be best, especially if vacuum is planned for,
but most of my stuff is cheap Chinese 
CAUTION : Hobby Chemist, not Professional or even Amateur
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wg48
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| Quote: Originally posted by unionised |
Lead glass is a good electrical insulator which helps, but the real reason they used it in CRTs was to block Xrays.
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Lead cannot be used to block x-rays in the front plate of colour CRTs as leaded glass darkens due to the effects of the electron beam. Barium and
strontium are used instead.
Leaded glass is used in the rest of tube and incidentally in light bulbs and florescent tubes because of its lower softening temperature and
suitability in making glass to metal seals
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aga
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Funny. I was trying out a vacuum distillation today and it was a nightmare.
At 100mBar it foamed like that geyser in yellowstone park that Yogi bear used as a bidet.
Bleeding PITA the whole thing.
In the end i got mad with the liquid and boiled it down in a beaker instead.
Got to 10% of the original volume with zero foaming.
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RawWork
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| Quote: Originally posted by wg48 | Leaded glass is used in the rest of tube and incidentally in light bulbs and florescent tubes because of its lower softening temperature and
suitability in making glass to metal seals
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Also because of resistance to extreme pressures.
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aga
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Does any amateur buy cheap glass and mess with Extreme pressures ?
No. Why not ?
Cos they all got killed during the experiment by Big shards of high-speed glass.
Evolution kinda took care of those types of amateurs, mostly.
Not many amateurs dabble in high pressure, apart from the hydrothermal nutjobs, and they use steel.
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Yttrium2
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Unfortunately I've had to throw away my kits, or return them.
I'll be on my 3rd or 4th
Things I've done are
fractional distillation of ether, to get the ether from a can of starting fluid
fractional distillation of ethyl alcohol
tried making ether, but wasn't measuring temperature in Celsius and I forget what happened after that, I didn't take good notes. If memory serves me I
didn't go on with the experiment because of the high heat needed, for some reason. Think it was something coupled with the fact that I didn't have a
pressure equalizing addition funnel...
I really haven't done too much.
When I was younger my parents freaked out when they saw lead balls, mixed with the ingredients for making black powder. They thought I was going to
make a claymore, or something. That was one of the first times I had to put my interests and enthusiasms on halt.
I have a very limited sense of what I can do with a simple setup, I should probably be focusing more on math and getting further ahead in school, that
way I can build more ideas but right now I guess I'm kind of burnt out (stressed out) and really really wanting to get this distillation kit.
There is a bit of a spiritual element to it for me. It gets me excited, I'll be able to use that excitement towards getting ahead in school... I
resonate with the fact that early distillations were done by alchemists trying to transmute base metals into gold. I too am trying to perform a
distillation, though it might be more so a matter of distillation of spirit. Looking back over the years, trying to find what I lost. I like the look
of the alembic, the pelican, the retort, or whatever you want to call them. I do see life and things as a spiritual journey. There is a substance I
can't capture nor define, yet. Sometimes I have it sometimes I don't, but when I do I fly. Like the early alchemists I too am trying to put things
through a bit of a crucible, trying to find a bit of spirit. Somewhere. Needless to say, I do take chemistry, school, and religion very seriously.
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zed
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Ummm.
I have purchased some Chinese Glassware recently.
Looks pretty good actually. Sturdy enough, but a little wonky. As in Cat-In-The Hat-ish.
It lacks the perfect symmetry of old-time American glassware. But, perhaps I mis-remember.
Might have been, in my wild youth, I was less discerning regarding symmetry.
I've broken my share of glassware. Sometimes, I am an inattentive maladroit. Moreover, a fair amount of my glassware, seemed to break itself.
Star cracks mysteriously appeared, in round bottom flasks. From Whence? It never mattered really. It was OK. Then suddenly, it was trash trash.
Buy another one.
If you have some budget, The Chinese can be very helpful. For I few hundred bucks, you can set yourself up with pretty nice array of glassware.
Seriously, American Glass with ground glass joints, was always pretty expensive. A very small kit, used to cost hundreds. And, that would be in the
BIG dollars of 50 years ago.
Nowadays, for a few hundred, you can put together a pretty decent collection of gear.
I've had decent luck with Deschem. From order, to delivery, from China to the US, about a week. Highly rated.
Next time out, I'll try Nanshing. They have a nice looking kit, for not very much.
Moreover, they seem to be receptive to allowing some substitutions.
I'd like to have flat bottom flasks.
https://www.ebay.com/itm/2000ml-24-40-New-Chemistry-Glasswar...
Like this Deschem kit also. With the inclusion of a Soxlet or a Dean-Stark, you could do most things.
https://www.ebay.com/itm/24-40-New-Organic-Chemistry-Laborat...
[Edited on 29-3-2018 by zed]
[Edited on 30-3-2018 by zed]
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