Sciencemadness Discussion Board

Cleaning glassware and other equipment

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j_sum1 - 1-7-2021 at 22:31

I use a lot of these one way or another. And it is annoying when I grab a handful and they look kind of smeary.

Lie them flat in a container. (I used an ice cream container.) Sprinkle liberally with sodium percarbonate. Pour a jug of boiling water over the top. When the fizzing stops, extract and enjoy.

Probably an old trick given that percarbonate is used to sanitise beer bottles. Probably extends to other glassware as well.

Herr Haber - 2-7-2021 at 00:57

"Other equipment"

Whenever I finish an ammonia bottle I drop my comb inside with a little bit of water.

Swirling it around for 30 seconds gives better resulsts than a pressure washer.

Barium sulfate residue

j_sum1 - 8-1-2022 at 20:09


Barium sulfate
BaSO4 is notoriously insoluble. I like to recycle Ba salts when I can and then render the rest inert before disposing. This invariably results in a fine layer of the sulfate clinging to the glassware. Especially annoying on filtration equipment and it looks really unsightly.

Rinsing with hardware store grade hydrochloric acid with a wee bit of mechanical action seems to work well. It might take a couple of rinsings with the acid. A surprising amount reappeared when running water over apparently clean flasks.

I also managed to hydrolyse the nylon bristles on my new flask brush, so watch out for that one.

MaeBorowski - 20-1-2022 at 16:06

I found that boiling sulfuric acid destroys any crap including elemental carbon, sulfur, barium sulfate, and most polymers. Unfortunately for mad science, I haven't unnecessary diamond. This method is gentle for glass, cheap, fast, reusable, eco-friendly etc. so you can try it if the piranha sucked a little.
Remember about SO2 releasing!

Crazy_Chemist - 26-3-2022 at 21:52

I bought som chromium (tri)oxide to have to clean my glass, but I'v understand theat is really dangerous and carcinogenic?

CycloRook - 7-4-2022 at 06:32

What is a good cleaner/solvent for glassware. I've been do alot of grignard reactions recently and have had a few run away from me.

Acetone and acetic acid worked pretty well but both smell really bad.

Is there something I could soak my glassware in overnight that would clean/destroyed/dissolve everything.

Water based would be best that doesn't smell.

ManyInterests - 4-7-2022 at 07:33

I used my glass buchner funnel (fritted glass) quite a bit, but right now after a sodium chlorate filtration it is really, really clogged. I am giving it a simple water wash, but it is trickling down to a bunch of drops.

I had something like this before, and I had to use HCl in order to clean my frit after making NHN (and neutralizing whatever is there with. But this is chlorate we're talking about, would it cause a violent reaction? I really need something to clear up my frit.

teodor - 4-7-2022 at 08:29

Quote: Originally posted by Crazy_Chemist  
I bought som chromium (tri)oxide to have to clean my glass, but I'v understand theat is really dangerous and carcinogenic?


After you dissolve it in conc H2SO4 it is safe to work in a cold state. I mean for an average chemical amateur with some experience in handling corrosive staff. But working (weighing etc) dry CrO3 or heating the chromic acid solution is something that requires good isolation between your breath and the staff. CrO3 either has a relatively high vapor pressure for such a corrosive compound or forms microdust, as a result, I can feel something like "pepper in my nose" when handling it.
Sodium dichromate is much easier to work but it is expensive compared to CrO3.
I believe CrO3 in conc. H2SO4 solution is quite good for removing even those BaSO4 strains mentioned by j_sum.

Also, the action of Cr(VI) on living cells is quite different for soluble and insoluble Cr(VI) compounds. Soluble compounds like sodium or potassium dichromates, CrO3 are very reactive, so they are usually reduced on the surface of cells and do not penetrate inside.
But sparingly soluble Cr(VI) dust penetrates cells and more likely can cause cancer (calcium, strontium, lead, zinc chromates, etc) if you are living in such an atmosphere - studies show that Cr(VI) cancer is the result of cumulative effect.




[Edited on 4-7-2022 by teodor]

PirateDocBrown - 4-7-2022 at 11:35

Quote: Originally posted by ManyInterests  
I used my glass buchner funnel (fritted glass) quite a bit, but right now after a sodium chlorate filtration it is really, really clogged. I am giving it a simple water wash, but it is trickling down to a bunch of drops.

I had something like this before, and I had to use HCl in order to clean my frit after making NHN (and neutralizing whatever is there with. But this is chlorate we're talking about, would it cause a violent reaction? I really need something to clear up my frit.


Start with boiling hot water. Much greater solubility at high temp.

I often protect my frit, by putting filter paper on top of it. Or just use a paper filter to start with.

PirateDocBrown - 4-7-2022 at 11:41

Quote: Originally posted by teodor  
Quote: Originally posted by Crazy_Chemist  
I bought som chromium (tri)oxide to have to clean my glass, but I'v understand theat is really dangerous and carcinogenic?


After you dissolve it in conc H2SO4 it is safe to work in a cold state. I mean for an average chemical amateur with some experience in handling corrosive staff. But working (weighing etc) dry CrO3 or heating the chromic acid solution is something that requires good isolation between your breath and the staff. CrO3 either has a relatively high vapor pressure for such a corrosive compound or forms microdust, as a result, I can feel something like "pepper in my nose" when handling it.
Sodium dichromate is much easier to work but it is expensive compared to CrO3.
I believe CrO3 in conc. H2SO4 solution is quite good for removing even those BaSO4 strains mentioned by j_sum.

Also, the action of Cr(VI) on living cells is quite different for soluble and insoluble Cr(VI) compounds. Soluble compounds like sodium or potassium dichromates, CrO3 are very reactive, so they are usually reduced on the surface of cells and do not penetrate inside.
But sparingly soluble Cr(VI) dust penetrates cells and more likely can cause cancer (calcium, strontium, lead, zinc chromates, etc) if you are living in such an atmosphere - studies show that Cr(VI) cancer is the result of cumulative effect.




[Edited on 4-7-2022 by teodor]


I generally use Cr(VI) as a last resort. Not only do you not want it on your skin, you don't want to risk it in the environment, either.

For cleaning glass, start with hot water, soap and physical agitation. By far the most effective for most things.

Acetone for organic gunk. Methanol for rinsing and drying.

Failing that, short baths in NaOH/isopropanol. Gotta be careful, too much can etch the glass, but it gets a lot of stuff out.

Piranha is for desperate cases, and it almost never fails.

Only then do I break out the chromate.

[Edited on 7/5/22 by PirateDocBrown]

ManyInterests - 4-7-2022 at 16:05

Quote: Originally posted by PirateDocBrown  
Quote: Originally posted by ManyInterests  
I used my glass buchner funnel (fritted glass) quite a bit, but right now after a sodium chlorate filtration it is really, really clogged. I am giving it a simple water wash, but it is trickling down to a bunch of drops.

I had something like this before, and I had to use HCl in order to clean my frit after making NHN (and neutralizing whatever is there with. But this is chlorate we're talking about, would it cause a violent reaction? I really need something to clear up my frit.


Start with boiling hot water. Much greater solubility at high temp.

I often protect my frit, by putting filter paper on top of it. Or just use a paper filter to start with.


I use coffee filters as well. But often times things go through anyway.

I did use more than a liter of boiling hot water, and boiling soap water as well. It definitely did good to clean it as water flowed through much faster, but there was still discoloration and something was stuck.

I did use 2 cups of dilute HCl solution in the end (2/3 water, 1/3 31.5 muratic acid) and that cleaned it up. The characteristic yellow color of destroyed chlorates came through. I wonder how so much got stuck despite the numerous hot water washes.


Cleaning new fritted/sintered filters?

Sulaiman - 14-4-2024 at 18:42

I've just ordered two fritted funnels, intending to filter some mercury.
(60ml, G3=15 to 40 um and G5=2 to 5 um)
The vendor suggests an initial clean with either hot hydrochloric acid (why HCl?)
or chromic sulphuric acid.
HCl fumes are not welcome in my temporary lab
and I don't want to deal with chromium waste.
Would piranha solution (or maybe aqua regia) be a suitable alternative?

bnull - 15-4-2024 at 06:37

Yes. A tip: put the funnels upside down, fill their lower half (through the stem) with part of the solution and, after the solution has passed through, turn them right side up and filter the rest of the solution. This way you will clean the funnels and unclog both sides of the frit.

Thanks, will do

Sulaiman - 15-4-2024 at 10:30


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