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Author: Subject: Aluminum BBs Vs. Lab Armor
EssOilChem
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[*] posted on 3-4-2012 at 09:04
Aluminum BBs Vs. Lab Armor


Been lurking on this board for quite some time and have learned alot, thanks for that.

I was wondering if anyone had used aluminum BBs (like the kind you use on BB guns/airsoft guns) for a bath on a hotplate stirrer combo. Would it be similar to the Lab Armor beads?

Anyone have any positives/negatives they would like to share on using such medium for a high(er) temperature bath? Is there any time when I would not want to use this due to risk factors?

Is there any cheaper metal beads/BBs that you would recommend? The Lab Armor ones seem to be very overpriced, but then again, I could just be missing something.

Thanks for your help.
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[*] posted on 3-4-2012 at 09:13


I use copper coated shot (bbs) for heat baths a lot lately. No mess, no scratching, and great thermal conductivity.



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[*] posted on 4-4-2012 at 11:45


Quote: Originally posted by Bot0nist  
I use copper coated shot (bbs) for heat baths a lot lately. No mess, no scratching, and great thermal conductivity.


Awesome, thanks for the reply, I may just do that considering those are much cheaper!
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[*] posted on 4-4-2012 at 21:43


I'm ashamed I hadn't thought of this. What is the practical temperature range? Do you set the flask in the vessel and then stream the BB's in? If you heat them on a hot plate is there a gradient? I might worry about hot spots depending on the vessel. As with mantles, they might form areas of focused heat. Have you checked for this? Overall its a really good idea.



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[*] posted on 5-4-2012 at 03:58


How do you raise/lower the bath to change the flask? Can it push its way into the shot bed without a lot of force?

I'm sick of oil and sand!




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[*] posted on 5-4-2012 at 05:50


I'm also interested in using BBs for heat baths, seems like a great mess-free idea. It sounds best suited to high temperature baths, but what about <100C? Water is simple enough to use of course, but it would be convenient to just have one bath for every situation. I'm interested in how this is done practically, and eager to hear answers to the questions of the other posters as well.
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[*] posted on 5-4-2012 at 07:32


I use water baths for under 100&deg;C needs. I haven't had trouble with the BBs yet, but I haven't ran any tests though. Heats up fast and holds temp well. Haven't noticed any real issues with localized heating yet. I can't take credit. I saw it in the "p-toluenesulfonic acid" thread, IIRC.



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[*] posted on 5-4-2012 at 14:13


Are BBs a real practical option to heat RBFs instead of an oil bath ?

I get the principle of it but could someone go into more detail ?

I am looking to equip myself with an oil bath but if BBs are better then finding them is the least of my concern.
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[*] posted on 5-4-2012 at 15:25


Check smuv's "Toluene --> Sodium Tosylate --> p-cresol" thread for pictures of the BBs in use. I just put a few inches in the bottom, put in the RBF, and fill around the sides. They can also be wiggled in if your careful. They get hot way faster than sand and don't scratch the glass. BBs will not work for every situation, but I find myself using them more and more. But for most of my work, a boiling brine bath will suffice.

See these threads on heating baths.

http://www.sciencemadness.org/talk/viewthread.php?tid=19089#...

http://www.sciencemadness.org/talk/viewthread.php?tid=17426#...


Here is smuv's thread with a pic.
http://www.sciencemadness.org/talk/viewthread.php?tid=15522

"I don't know if they are copper (probably plated), but they are BB's for airguns. They work much better (and less mess) than sand." ~smuv


[Edited on 6-4-2012 by Bot0nist]




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[*] posted on 5-4-2012 at 17:12


For what it's worth: usually BBs are copper plated steel shot. True copper shot is pricey and while y'all might have a source: I can't point you in any direction on that.
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[*] posted on 5-4-2012 at 18:09


Quote: Originally posted by Bot0nist  
Check smuv's "Toluene --> Sodium Tosylate --> p-cresol" thread for pictures of the BBs in use. I just put a few inches in the bottom, put in the RBF, and fill around the sides. They can also be wiggled in if your careful. They get hot way faster than sand and don't scratch the glass. BBs will not work for every situation, but I find myself using them more and more. But for most of my work, a boiling brine bath will suffice.

See these threads on heating baths.

http://www.sciencemadness.org/talk/viewthread.php?tid=19089#...

http://www.sciencemadness.org/talk/viewthread.php?tid=17426#...


Here is smuv's thread with a pic.
http://www.sciencemadness.org/talk/viewthread.php?tid=15522

"I don't know if they are copper (probably plated), but they are BB's for airguns. They work much better (and less mess) than sand." ~smuv


[Edited on 6-4-2012 by Bot0nist]
Holy hell that lab is filthy :D

wouldn't steel shot interface badly with a stir bar ?

I may just go with both an oil and BB bath (not at the same time though).

Damn that Toluene --> Sodium Tosylate --> p-cresol thread gets me so excited , that's one of the things I love about chemistry , it's like this never ending adventure and I just want more more more :o


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[*] posted on 5-4-2012 at 18:38


Yes, no mag stirring with a steel shot bath. I stated that they were copper coated, BTW. Oil and water baths are still necessary in many situations. Air baths work great too. Use a foil skirt. See the other threads I linked. Many more to be found on TFSE.



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[*] posted on 6-4-2012 at 00:16


Good to know.

BTW I like your sig ;)
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[*] posted on 6-4-2012 at 02:02


Quote: Originally posted by Bot0nist  
Oil and water baths are still necessary in many situations. Air baths work great too. Use a foil skirt. See the other threads I linked. Many more to be found on TFSE.


I can't imagine they provide the same level of uniformity in the temperature distribution across the glass versus an oil bath, given that they're making limited point contact (best way to reduce contact area, make it spherical; e.g. balls in ball bearings). But they'll certainly be cleaner than oil.

The photo isn't that messy, it's just the paint on the wood that's making it look mucky. Same thing set up on one of those snazzy HDPE surfaces wouldn't look too bad. Provided it gives the same results and is sturdy, no problems. Maybe give the hotplate a wipe. :D

[Edited on 6-4-2012 by peach]
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[*] posted on 6-4-2012 at 03:03


I'd be weary of hot spots using regular BB's - I can imagine the point of contact between them and the glass surface would cause considerable stresses. I guess you could circumvent this by using smaller spheres of maybe 2-3mm diameter. Pure copper or aluminium shot would be better for heat conduction, as would silver if you're minted enough!
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[*] posted on 6-4-2012 at 06:59


Quote: Originally posted by DJF90  
I'd be weary of hot spots using regular BB's - I can imagine the point of contact between them and the glass surface would cause considerable stresses. I guess you could circumvent this by using smaller spheres of maybe 2-3mm diameter. Pure copper or aluminium shot would be better for heat conduction, as would silver if you're minted enough!


I've never felt or seen the lab armor aluminum baths in person, would that add the same type of stress on the glass in higher temp situations? Any ideas on what type of consumer (easy to get and cheap) products that are aluminum (for a stirring plate heat bath) would be a viable alternative to BBs or lab armor?

Edit: Perhaps even regular sized aluminum pellets or BBs, then covering the submerged portion of the flask with thin aluminum foil to evenly distribute the heat conducted by the spheres? I believe that would solve the heat distribution problem.


[Edited on 6-4-2012 by EssOilChem]
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[*] posted on 6-4-2012 at 08:10


http://www.ebay.com/itm/1lb-Bag-of-Aluminum-Pretreated-Alumi...
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[*] posted on 6-4-2012 at 08:25


Quote: Originally posted by Moiety  
http://www.ebay.com/itm/1lb-Bag-of-Aluminum-Pretreated-Alumi...


What about the aluminum sandblasting media (alumina - oxide) or is that flammable? Sorry for my ignorance on the compound, I just saw online that it can be had for like $30 - $40, tiny grain, like 25 lbs.
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[*] posted on 6-4-2012 at 08:29


Quote: Originally posted by EssOilChem  

What about the aluminum sandblasting media (alumina - oxide) or is that flammable? Sorry for my ignorance on the compound, I just saw online that it can be had for like $30 - $40, tiny grain, like 25 lbs.

That would be quite abrasive, wouldn't it? Not good for glassware at all. Also, I think aluminium silicate is the most used sandblasting agent, though I could be wrong. Neither of them are flammable.




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[*] posted on 6-4-2012 at 08:51


I'm sure you could get soft aluminium oxide, but it's also a refractory (insulator). Saying that, sand isn't a great conductor but is common around mantles. Plus, it's free at your local beach - twigs, biros, tampon applicators and seaweed included. There's even some free medical waste in there if your beach is close to mine, could be some good stuff mixed in! ;)

Diamond is about five times better than copper in terms of heat conduction, for the ultimately wealthy mantle owner.
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[*] posted on 6-4-2012 at 09:12


Quote: Originally posted by peach  
I'm sure you could get soft aluminium oxide, but it's also a refractory (insulator). Saying that, sand isn't a great conductor but is common around mantles. Plus, it's free at your local beach - twigs, biros, tampon applicators and seaweed included. There's even some free medical waste in there if your beach is close to mine, could be some good stuff mixed in! ;)

Diamond is about five times better than copper in terms of heat conduction, for the ultimately wealthy mantle owner.


haha @ free medical waste.
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[*] posted on 6-4-2012 at 13:22


Quote: Originally posted by EssOilChem  
Quote: Originally posted by Moiety  
http://www.ebay.com/itm/1lb-Bag-of-Aluminum-Pretreated-Alumi...


What about the aluminum sandblasting media (alumina - oxide) or is that flammable? Sorry for my ignorance on the compound, I just saw online that it can be had for like $30 - $40, tiny grain, like 25 lbs.
I actually use aluminum oxide to sandblast all kinds of metal , it's is one of the more aggresive medias to use so using it for a bath would be even worse than sand:o

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[*] posted on 6-4-2012 at 14:05


I spent today jet washing someone's garden at 3,000 psi with a 13hp washer. Fun stuff!

The alumina used for blasting is produced by melting oxides, letting it cool, crushing it and then sieving. That method (the bulk fracturing of lumps) means that the resulting grit has sharp edges to cut away at paint, barnacles, scale, gunk, etc.

There's an interesting video from one of the manufacturers showing the process, here.

Aluminium oxide dust, from grinding through refractory, is kind of soft feeling by comparison.

I remember going to a place that sold refractory when I was about 16, to get some bricks. The place looked like a Columbian coffee factory with guys in air fed bunny suits walking around, surrounded by clouds of white dust.
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[*] posted on 6-4-2012 at 19:31


The tech specs for lab armor only give uasable range to 180C max ,kind of disappoimting. Material is stated as "metal beads",which could be anythiing,presumably alloy.
Small brass bearings are available and may be suitable for use with magnetic stirring.




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[*] posted on 7-4-2012 at 12:23


Quote: Originally posted by peach  
I spent today jet washing someone's garden at 3,000 psi with a 13hp washer. Fun stuff!

The alumina used for blasting is produced by melting oxides, letting it cool, crushing it and then sieving. That method (the bulk fracturing of lumps) means that the resulting grit has sharp edges to cut away at paint, barnacles, scale, gunk, etc.

There's an interesting video from one of the manufacturers showing the process, here.

Aluminium oxide dust, from grinding through refractory, is kind of soft feeling by comparison.

I remember going to a place that sold refractory when I was about 16, to get some bricks. The place looked like a Columbian coffee factory with guys in air fed bunny suits walking around, surrounded by clouds of white dust.
Here is a fun tip (although I have never tried it) that I have heard people use for large projects.

I'm not sure of the procedure but basically you put sand in your pressure washer and it is supposed to tear paint apart.

I remember a guy who restores school buses tell me this ;)
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