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Author: Subject: Bad days in the lab or with glassware?
XeonTheMGPony
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[*] posted on 27-5-2018 at 20:21


Quote: Originally posted by zed  
Quote: Originally posted by nitro-genes  
Destroying your electric coffee grinder trying to grind steelwool into a powder for nitroarene reduction... only to find that iron powder and magnetic stirring don't work together anyway. :)


Ah, your pain will be very helpful to me indeed. I still may try this as an experiment, but mostly without the expectation of success!

Thank you!


don't forget very fine iron dust is super flammable! and can auto ignite if fine enough!
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Hegi
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[*] posted on 28-5-2018 at 01:45


Quote: Originally posted by nitro-genes  
Destroying your electric coffee grinder trying to grind steelwool into a powder for nitroarene reduction... only to find that iron powder and magnetic stirring don't work together anyway. :)


I really love this post and can relate to such a thing happening to me... It is funny to see that scientists can figure out solutions for complex problems but fail at those simple ones... :) :) :)




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Morgan
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[*] posted on 28-5-2018 at 06:51


Quote: Originally posted by Hegi  
Quote: Originally posted by nitro-genes  
Destroying your electric coffee grinder trying to grind steelwool into a powder for nitroarene reduction... only to find that iron powder and magnetic stirring don't work together anyway. :)


I really love this post and can relate to such a thing happening to me... It is funny to see that scientists can figure out solutions for complex problems but fail at those simple ones... :) :) :)


That reminded me of this NASA mistake.
"In June 1988, the Discovery Space Shuttle mission was delayed because of a malfunctioning hydrogen fuel bleed valve system. The problem was traced to the linear variable differential transformer (LVDT) which produced erroneous readings for the valve position. Near liquid hydrogen temperatures, Inconel 718 used in the armature of the LVDT became strongly magnetic."
https://link.springer.com/chapter/10.1007%2F978-1-4613-9880-...

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nitro-genes
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[*] posted on 30-5-2018 at 15:46


It is always one of these unforeseen interactions in seemingly simple systems that can make large differences indeed or even lead to accidents. I mean...who could have actually predicted "a priori" that the iron powder would all cling like a single ball to the stirrer bar? :D

Quote: Originally posted by zed  


Ah, your pain will be very helpful to me indeed. I still may try this as an experiment, but mostly without the expectation of success!

Thank you!


If you are planning to use it for reductions... a much easier method is to compact small strands of steelwool into round balls. These hardly interfere with magnetic stirring at all and are much more dense than the loose steelwool itself, while retaining surface area.





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Okaris
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[*] posted on 2-6-2018 at 00:27


I've had the ceramic mortar break into two while I was grinding my samples. Fortunately, it was nothing that super glue couldn't fix.
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The Volatile Chemist
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[*] posted on 2-6-2018 at 17:57


Quote: Originally posted by Hegi  
Quote: Originally posted by nitro-genes  
Destroying your electric coffee grinder trying to grind steelwool into a powder for nitroarene reduction... only to find that iron powder and magnetic stirring don't work together anyway. :)


I really love this post and can relate to such a thing happening to me... It is funny to see that scientists can figure out solutions for complex problems but fail at those simple ones... :) :) :)

At work I've been having plumbing trouble with a reactor design. Every time I come up with a good plan, halfway through the reviews someone points out something obvious I've missed, like the fact that you can't pull a vacuum through a flow-meter...

I went into my (own) lab today to do a little cleaning, since I haven't been able to do home-chem in a while, and I found that I had ruined about 6 wells in my plastic well plate by letting some solutions of butanol and butyl acetate sit in them unfortunately. They turned crusty white and the plastic became deformed and thinned in those wells.




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LearnedAmateur
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[*] posted on 12-6-2018 at 10:23


Who needs to use their brains and undo the right clamp anyway?

CE4634AC-08E0-4CF5-BE92-B040CFAA9666.jpeg - 816kB




In chemistry, sometimes the solution is the problem.

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weilawei
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[*] posted on 16-6-2018 at 17:43


Broke a 50mL beaker just now by dropping my phone onto it. Thankfully, it was not in use.

Ahhh.. time to order a new one.

20180616_214042.jpg - 2MB
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Magpie
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[*] posted on 16-6-2018 at 18:33


Seeing a wisp of smoke rising from your stepper motor driver constitutes a bad day. Fortunately I have a spare.



stepper motor driver.JPG - 220kB




The single most important condition for a successful synthesis is good mixing - Nicodem
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weilawei
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[*] posted on 17-6-2018 at 07:49


I have 5 drives from work, pulled because they claimed they didn't work. I haven't got around to testing them or figuring out what they need for repairs, but if anyone wanted them for parts, I'd be happy to work something out. Otherwise, I'll keep them around till my buddy and I evaluate and maybe repair them for eBay.

[Edited on 17-6-2018 by weilawei]

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JJay
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[*] posted on 2-7-2018 at 21:54




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wg48
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[*] posted on 2-7-2018 at 23:48


Quote: Originally posted by Magpie  
Seeing a wisp of smoke rising from your stepper motor driver constitutes a bad day. Fortunately I have a spare.


Perhaps you should try a hand cranked one ;).

182668__b_.jpg - 73kB




Borosilicate glass:
Good temperature resistance and good thermal shock resistance but finite.
For normal, standard service typically 200-230°C, for short-term (minutes) service max 400°C
Maximum thermal shock resistance is 160°C
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XeonTheMGPony
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[*] posted on 3-7-2018 at 04:35


Was freeze drying some copper nitrate, well the crystallizing dish objected to the prerequisite freezing and turned its self into a great many pieces :( Thank fully I ordered a second one from Deschem, so now it will just be the new one Vs the second, I think I'll order several more.

and not so much glasses fualt ran a hydrazine sulfate synth that from all appearances failed.
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[*] posted on 4-7-2018 at 11:33


Just broke my Claisen adapter. GRRRRRRR.




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[*] posted on 4-7-2018 at 14:09
Ooops !


Maybe I should change my "I don't need to wear my gloves" attitude ?

Aqua Regia vs. middle finger .....
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Not painful ... just embarrassing
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XeonTheMGPony
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[*] posted on 4-7-2018 at 17:18


that looks very painfull! I wash my hands between every operation regardless if I feel any thing just for that reason!
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Doped-Al2O3-fusion
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[*] posted on 6-7-2018 at 13:31


I recently had a sad accident. The solution I was filtering was ferrous sulfate and I failed to secure my vacuum pump as I normally do. I accidentally got caught on the power cord and then sadness occurred.

I got online later and ordered two more of the same size, plus an additional coarse glass Buchner funnel. I may receive them next week or in a month or so since I order from the Chinese manufacturer directly.

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[*] posted on 7-7-2018 at 12:19


Sad day... :'(

Cracked the top of my hotplate.





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[*] posted on 14-7-2018 at 15:01


While doing a steam distillation of sage, I got distracted and let my RBF boil to dryness. My hotplate was on its highest setting and the flask was insulated with foil so the heat built up quickly. What you see in the photo is the surface of my hotplate glowing a dull red with pieces of melted aluminum foil. I was impressed that my plate could get that hot but also a little worried that it might damage the flask so me in my stupidity poured water into the flask to cool it down causing it to crack from thermal shock.

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Sulaiman
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[*] posted on 16-7-2018 at 07:19
differential thermal expansion ?


I opened one of my glassware boxes and found a broken Claisen adapter,
I know that the box has not been miss-handled since last use.
When put it away the weather was cold and I left a very solid ptfe 24/29 overhead stirrer gland in the neck,
we are presently having a (relaively) hot summer.
ptfeClaisen.jpg - 730kB

Is it likely to be due to the difference in thermal expansion ?
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[*] posted on 16-7-2018 at 10:06


Quote: Originally posted by Sulaiman  



Is it likely to be due to the difference in thermal expansion ?


Not unless your Claisen adapter was poorly constructed, which looks likely. I had the same thing happen once at around 100 C with a very similar looking Claisen adapter. Stir bearings shouldn't break ground glass joints at temperatures associated with ordinary use.




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Sulaiman
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[*] posted on 16-7-2018 at 10:25


D'oh ! ... I am an idiot !
Of course the ptfe and glass have to work reliably at much higher temperatures/temperature changes.

The adapter does seem poorly made,
part of the joint at the junction has so many bubbles that it looks like the milky way :D

Not a disaster as I also have a 24/40 Claisen, but I want to replace it eventually.
I'll just write this one off as 'unknown.'
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[*] posted on 16-7-2018 at 13:21


Yeah, but at higher temperatures ptfe flows more easily... The thermal expansion is more likely to cause a joint to crack if it is assembled cold, and then brought to room temp; for example, tightening a stopcock in the freezer, and then letting it warm to room temp. Rather than operating at high heat, which makes the ptfe much less rigid.

Ptfe has a much, much larger CoE than boro.

I have lost a couple pieces this way. If ever the joint is going to be heated, I am careful not to make it too snug.

Also, when I put sep funnels in the freezer, I have to tighten the stopcock periodically as it cools, or it will leak. And loosen it as it warms up.

Also, beware chinese glass. You guys have a lot more faith in deschem and nanshin than I do! Never again nanshin for me.
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[*] posted on 17-7-2018 at 08:26


What bad experience did you have with their glassware?
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happyfooddance
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[*] posted on 17-7-2018 at 09:19


Quote: Originally posted by CobaltChloride  
What bad experience did you have with their glassware?


20160421_035956.jpg - 894kB

You get what you pay for.

I've had about a dozen pieces of cheap chinese glass, and two years later not a single piece was intact. In that two years I broke more glass than ever in my life.

The craftsmanship is terrible. Almost every piece has multiple bubbles, nothing is annealed properly... What is the point of having borosilicate if it isn't at least slightly resistant to thermal shock? I feel like if they used soda-lime glass it might be a little better quality, if not chemically inert.

But what good is chemical resistance when your flask breaks unexpectedly?

I get my glass from Laboy or Dr. Bob. Great quality, great price.

My equipment sees a lot of use, so others might have different standards... But I don't consider it saving money if the equipment fails prematurely and unexpectedly.
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