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Author: Subject: Cleaning glassware and other equipment
j_sum1
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[*] posted on 20-10-2017 at 02:49


I came up with an ingenious idea when cleaning up some glassware the other day.

I had a 500mL flask with what seemed to be a particularly persistent deposit. I tried the usual routines -- hot soapy water, lots of mechanical scrubbing, strong base, oven cleaner and as a last resort, piranha solution. Nothing I tried would remove the yellow-brown marks.

I was about to give up and then I tried scrubbing the outside of the flask. Worked like a charm.
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Melgar
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[*] posted on 20-10-2017 at 03:13


Ah yes, I think we've all been there more times than we'd like to admit.

As far as your basic organic crud that's not very hard to get off, well, I realized at one point that I was wasting quite a bit of $20/gallon isopropanol, methanol, and acetone just rinsing out organics. Switched to automotive windshield washer fluid as my cleaner of first resort, and I have to say it's a great deal at $2 or so a gallon. I also use it as the coolant for distillation. One nice thing about it is that it doesn't leave residue if you accidentally spill any. Also, mold and other microorganisms will grow in dilute isopropanol. Not so for methanol.




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CharlieA
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[*] posted on 20-10-2017 at 17:05


My go-to cleaning soap, after rinsing with an appropriate solvent, is "seventh generation dish detergent powder". Surprisingly (at least to me) the list of ingredients given on the back of the box is the same as the list of ingredients in the SDS. It is phosphate-free (I guess the old Alconox has bit the bullet?:D).

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Sulaiman
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[*] posted on 21-10-2017 at 01:38


I have experimented with acids and bases, oxidisers, detergents ..
I find that whichever cleaning solution is used, mechanical scrubbing always helps a lot,
my favourite is c3mm soda glass beads http://www.ebay.co.uk/itm/FD4636-FLINT-GLASS-SODA-LIME-BEADS...
as they work well and so far show no signs of scratching my flasks insides.
Swirled - not shaken.
They are easy to rinse and re-use.




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CobaltChloride
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[*] posted on 16-3-2018 at 03:44
Cleaning a RBF


My distillation apparatus recently came so I decided to acquaint myself with it by distilling some tap water. After the distillation, I noticed there are white streaks on the inside. I tried cleaning with hydrochloric acid as I thought it was some calcium carbonate/ magnesium carbonate, but it didn't go away even after scrubbing with steel scrubbing pads. How do you think I could remove this? I noticed there are white deposits on my pots as well that don't dissolve in HCl, so it's clearly something in the water. It could be calcium sulfate, which would mean it should be removed by hot, concentrated sodium hydroxide (https://pubs.acs.org/doi/abs/10.1021/ie50436a015). What do you think I should use to remove it?
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[*] posted on 20-7-2018 at 05:26


A new active discussion happening here:
https://www.sciencemadness.org/whisper/viewthread.php?tid=85...

No new methods suggested AFAICS and so I will leave that one alone for whatever discussion might ensue -- rather than merging it.
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Melgar
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[*] posted on 20-7-2018 at 05:41


Using a sponge or a rag attached to the end of a stiff wire (like a coat hanger wire) works well for cleaning things like erlenmeyers and RBFs. You bend it into whatever shape is best suited for reaching the spot you need to get, then work it into position.



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[*] posted on 20-7-2018 at 09:22


Quote: Originally posted by Melgar  
Using a sponge or a rag attached to the end of a stiff wire (like a coat hanger wire) works well for cleaning things like erlenmeyers and RBFs. You bend it into whatever shape is best suited for reaching the spot you need to get, then work it into position.


A sccouring pad can also be used with this method.

sco1.jpg - 4kBsco2.jpg - 5kB
sco.jpg - 6kBsco 4.jpg - 9kB

Also the sponge-backed pad when wet can be made to move round a spherical flask by vigorous shaking of the flask in a circular motion. Stainless steel scouring pads can also be used but there is a risk of scratching the flask.

The scouring pad can also be tie wrapped round a metal weight and used as above.




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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[*] posted on 20-7-2018 at 11:11


Quote: Originally posted by CobaltChloride  
My distillation apparatus recently came so I decided to acquaint myself with it by distilling some tap water. After the distillation, I noticed there are white streaks on the inside. I tried cleaning with hydrochloric acid as I thought it was some calcium carbonate/ magnesium carbonate, but it didn't go away even after scrubbing with steel scrubbing pads. How do you think I could remove this? I noticed there are white deposits on my pots as well that don't dissolve in HCl, so it's clearly something in the water. It could be calcium sulfate, which would mean it should be removed by hot, concentrated sodium hydroxide (https://pubs.acs.org/doi/abs/10.1021/ie50436a015). What do you think I should use to remove it?


I think it is calcium carbonate... Try hotter HCl. I didn't look at your link, but calcium sulfate is moderately soluble in boiling water, even a good stream of hot water gets it all out any time I've dealt with. Calcium carbonate can be a pain, even with dilute HCl, but if you put 20% in your flask and throw a reflux condenser on it and some heat under it, it should dissolve quickly.
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[*] posted on 20-7-2018 at 11:33


It is essential to make sure that any traces of calcium are removed before trying things like chromic acid and piranha solution, or you risk forming calcium sulfate, which sometimes sticks to glass. It can be hard to remove, but scrubbing will take it off.

I usually use dilute acetic acid to remove other calcium salts, but it can take a while to react sometimes.

[Edited on 20-7-2018 by JJay]




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