Sciencemadness Discussion Board

Cleaning glassware and other equipment

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Antiswat - 11-5-2013 at 12:01

I thought it would be a good idea to have a thread where we can discuss/contribute with different 'tricks' or facts about different kinds of substances/surfaces.
As im pretty sure all of us on here does chemistry that will ofcourse involve cleaning up afterwards, in a such way theres still some 'laboratory' left (;

So lets see...


Glassware:
Basically for any type of stains i would say hydroxides, highly concentrated solutions, preferably hot.
This will or should remove a tiny layer depending on how long time its cooked in the container, if you have say.. carbon on the sides of a container the glass its attached to's surface will be etched away, still this is just the absolute surface and not the entire glass.


Spills:
I happen to have a wooden table of some sort coated with something, anyhow sometimes all kinds of things decides to sink down into it, including some nickel tetraammine just lately, leaving a huge purple spot, anyhow i got partially rid of it with a new 'method' i discovered by somewhat accident while grinding up CuO in my heavily Fe2O3 stained mortar.

The CuO was dominating all the Fe2O3, when i added HCl it instantly turned into CuCl2 and somehow the Fe2O3 was removed also, this can be done aswell with tables as long as youre not able to directly soak them in it, which could leave some CuCl2 in it, impossible to get away.

I havent gotten 100% rid of the tetraammine stain tho, but i started with conc. ammonia, then rubbed CuO on it with great force (very little wettened CuO) as in with a bottlecap.

The rest is pretty selfexplanatory, tho i did one more thing:
i raised the heat while the CuCl2 and HCl was on there with aluminium foil, this reacts vigourously and gets hot very fast, and ofcourse hydrogen is formed.

H2O2 seemed as a good idea, somehow it turned the nearly invisible stain into green (i gave up trying to understand what happened at this point) whereafter i needed a few CuO washes to make it nearly invisible again.

Sandpaper is usually good, especially very fine sandpaper thats worn out for sinks and such.

For copper i guess you could try vinegar + salt, works surprisingly well to clean up copper based coins.

For a carpet im not really sure of how to do it, i guess you just wanna neutralize if possible, then soak it all in water and drag the liquid out using paper, perhaps if its insoluble first try with vacuum cleaner then try to dissolve it and remove it while dissolved.

For KMnO4, im not sure how useful this would be but, to turn KMnO4 almost colourless you could try adding NaOH and sugar solution to turn it more transparent, if you want to avoid using gloves this could make sure you dont have contact with KMnO4 but rather some hydroxides, abit of sugar and MnO2.


Yourself as in your hands:
Theres a few things infamous for making some pretty neat stains on yourself being KMnO4 and ofcourse MnO2.

KMnO4 is said to be more easily removed with use of lemon juice (i guess citric acid for higher efficiency)

For MnO2 you should be able to use NaHSO3 or concentrated HCl, if this is succesful you can smell SO2 coming off with the NaHSO3, so you know that something is happening at least.


About stains on objects i havent actually tried removing MnO2 stains with my CuO method, but its plausible to work aswell, of what i see it has great potential and making or buying CuO isnt that hard.
It will also allow for speeding it up with adding a metal thats reactive to HCl.

Potentially for carbon stains you could try heating up some nitrate, but problem would be if you heated the glass (assuming its glass) too fast resulting in it breaking apart.

Give in with ideas

Edit: Made title more descriptive

[Edited on 8-6-2017 by zts16]

Adas - 11-5-2013 at 12:31

This one should be sticky.

I have a similar method to your CuO/HCl method. It is used also industrially in some processes, AFAIK.
You can try, for example: You do not have any HCl yet and you have brown stains from KMnO4 inside your glassware. Just take some dilute H2SO4 (which can not remove it by itself) and add some Zn or ZnSO4. Heat it up and the stains are gone. It works by displacing the zinc in ZnSO4 by Mn, which goes into solution, and the formed ZnO dissolves again. So it is a catalyst.

Antiswat - 12-5-2013 at 05:36

oh yes.. stains from KMnO4 as in MnO2.. i might try that, but im not sure what i should use for it tho.. glass would be too easy i think..
ill definately try it.. but ZnO reacts pretty fast with acids, so if we cover the surface of something with that, which is stained its likely to act the same way as with CuO

woelen - 12-5-2013 at 06:32

I made this thread sticky. Cleaning (and more general, working cleanly) is an important aspect of practical chemistry. It is good to have ideas about this collected in a single thread and ready to be read. I would like all contributors to adhere to some practical rules:
- Do not post speculative and vague procedures in this thread, let's keep things practical and useful.
- If dangerous cleaning procedures are posted, then clearly warn about the dangers and clearly specify why such a dangerous procedure should be used. An example which comes to my mind is the use of piranha solution in some cleanup procedures, or the use of hot chromic acid in sulphuric acid.

weiming1998 - 12-5-2013 at 06:43

Glassware containing char/large chunks of carbonized organics stuck to it can be cleaned cheaply and safely with a boiling mixture of sodium hypochlorite (bleach is alright, but more concentrated pool grade stuff works better) and vinegar. I found that this softens the rock hard char so that it can be removed easily by scraping or might even pop off by itself. It takes some time though, but is much safer (cheaper too!) than using something like piranha solution or a mix of chromic and sulfuric acids, although it does smell a bit and can produce small amounts of chlorine gas (so this should be done outside).

Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.

Antiswat - 15-5-2013 at 01:35

Quote: Originally posted by weiming1998  
Glassware containing char/large chunks of carbonized organics stuck to it can be cleaned cheaply and safely with a boiling mixture of sodium hypochlorite (bleach is alright, but more concentrated pool grade stuff works better) and vinegar. I found that this softens the rock hard char so that it can be removed easily by scraping or might even pop off by itself. It takes some time though, but is much safer (cheaper too!) than using something like piranha solution or a mix of chromic and sulfuric acids, although it does smell a bit and can produce small amounts of chlorine gas (so this should be done outside).

Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.


about NaClO concentration, i have been able to not only make NaClO extremely concentrated, but actually still being NaClO and not NaCl + NaClO3 EVEN after i boiled it down into a solid several times.
several times i had to repeat this in order to get NaClO3, or well this was infact KClO but surely very same properties as NaClO
in short, with careful heating NaClO should be possible to concentrate just as with H2O2 (:

thanks for making it a sticky, first realise now why i didnt find the thread looking under the non-stickies :D

woelen - 15-5-2013 at 03:16

Quote: Originally posted by Antiswat  
oh yes.. stains from KMnO4 as in MnO2..
A very good way of removing such brown stains is rinsing with an acidified solution of sodium sulfite or bisulfite. Stained glass becomes clear again at once. Equally well works a solution of 1% H2O2 in dilute acid. Both solutions reduce the brown MnO2 to colorless Mn(2+), which goes into solution at once.

Antiswat - 15-5-2013 at 06:10

oh yes acidified H2O2
my hands are pretty well covered in MnO2 speaking about it.. i might try that..
tried 30% HCl and solid NaHSO3 rubbed on my hands then small amounts of water added
even both at once.. forgot NaHSO3 and HCl reacts :s

another one giving the reason for my MnO2 covered hands is water, oxalic acid and conc. H2SO4
on turning MnO2 into MnSO4 for then MnCO3 and finally Mn(NO3)2 you can use 300 mL water, 30g oxalic acid and 12 mL 98% H2SO4
the H2SO4 becomes fairly dilute so i doubt this would have much of a danger to your hands unless if you fall asleep with your hands in the solution
what happens is the oxalic acid first reacts with the MnO2 to reduce it, whereafter the H2SO4 is capable of reacting with it

DeadHead - 15-5-2013 at 06:58

Quote: Originally posted by weiming1998  
Glassware containing char/large chunks of carbonized organics stuck to it can be cleaned cheaply and safely with a boiling mixture of sodium hypochlorite (bleach is alright, but more concentrated pool grade stuff works better) and vinegar


Found what is likely my last surviving piece of lab glassware, a beaker with burned down black gunk in it...It was 10 years ago I don't remember what but something boiled dry on me I think. Gonna try this I think.

MrHomeScientist - 16-5-2013 at 05:42

Quote: Originally posted by weiming1998  
Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.


I have an anecdote I'd like to add to this. A friend of mine was etching circuit boards on his back porch and ended up with a lot of ferric chloride stains on the concrete floor. He tried my oxalic acid on that, but it did not work to clear it up. The stain would seemingly disappear, but when the deck was rinsed it would show up again. I think concrete is too porous for much of anything to work well. He might have to resort to using my hydrochloric acid for the purpose it was intended - etching concrete!


I've also found that minor iron stains on glassware can be removed by a soak in hardware-store-grade HCl over a day or two.

Antiswat - 16-5-2013 at 11:09

Quote: Originally posted by MrHomeScientist  
Quote: Originally posted by weiming1998  
Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.


I have an anecdote I'd like to add to this. A friend of mine was etching circuit boards on his back porch and ended up with a lot of ferric chloride stains on the concrete floor. He tried my oxalic acid on that, but it did not work to clear it up. The stain would seemingly disappear, but when the deck was rinsed it would show up again. I think concrete is too porous for much of anything to work well. He might have to resort to using my hydrochloric acid for the purpose it was intended - etching concrete!


I've also found that minor iron stains on glassware can be removed by a soak in hardware-store-grade HCl over a day or two.


i think your mate may have a serious problem.. tell him to cover it up (:
as of what i have seen FeCl3 goes into Fe2O3 over time and thats really a bitch to attempt removing.. i got a table stained with that stuff all over, to my luck its a smooth surface unlike concrete, where i can then use CaO + HCl method on it..
careful HCl etching (dilute?) and then sudden neutralization when wanted result is acquired might be the thing for him..
dont know how smooth concrete were talking about here tho

that last sentence sounded hilarious to me, no idea how tho..

amazingchemistry - 16-5-2013 at 21:43

I'd like to add the following: I work with iodine a fair bit, and consequently my clothes sometimes get nasty, otherwise unwashable brown stains. I was told to try dilute sodium thiosulfate. It worked wonders, but only if you treat the stain right after it happens.

Antiswat - 1-6-2013 at 03:49

on a sitenote process stated by Adas can potentially with 37% H2SO4 and 900 mesh zinc powder evolve SO3 so have some ammonia ready (=
you can recognize this gas by breathing through your mouth and if you get the feeling of a bus covered in P80 sandpaper sliding down your throat, then theres SO3 in the air ^^

DubaiAmateurRocketry - 10-6-2013 at 21:51

I got copper oxide decomposed from a copper salt in test tube. It solidified to the tube, don't want to waste tubes :p .. any ideas ?

elementcollector1 - 10-6-2013 at 21:56

Any acid should work to get rid of the copper oxide - I'll recommend sulfuric or hydrochloric (given the availibility of the former). Vinegar can also be used.

I found that to remove a tough, brownish-black stain on one of my RBF's, stoppering it with some soap, water and a quarter-flask's worth of sand, followed by a good, hard shake for 2-3 minutes works wonders.

Antiswat - 6-7-2013 at 15:13

indeed, idk about acetic acid but HCl works straight away
green colour and.. you could add some aluminium to it and then drop HCl on, the heat will raise the reaction temperature

can you have test-tube-phobia anyhow?
dont want testtubes, surely gonna end up filling up a test tube with solid carbon and thats kind hard to remove

bfesser - 6-7-2013 at 15:45

Quote: Originally posted by Antiswat  
Yourself as in your hands:
Theres a few things infamous for making some pretty neat stains on yourself being KMnO4 and ofcourse MnO2.
KMnO4 is said to be more easily removed with use of lemon juice (i guess citric acid for higher efficiency)
<iframe sandbox width="420" height="315" src="http://youtu.be/FAKcWM-yBkI?t=13m10s?rel=0&t=13m10s" frameborder="0" allowfullscreen></iframe>
<a href="http://www.orau.org/ptp/collection/accidents/ornldeconkit.htm" target="_blank">
Quote:
Finally the outer layer of skin might be removed with a 4% solution of potassium permanganate. The purple stain from the permanganate would be removed with 4% sodium bisulfite. <img src="../scipics/_ext.png" />
</a>

[Edited on 14.1.14 by bfesser]

Morgan - 6-7-2013 at 17:41

Today I was going to thread/tap a thick piece of stainless steel tubing and decided to anneal it first by heating it to a red heat and letting it cool slowly. As the metal was being blowtorched, it started to discolor greatly, moreso apparent a little distance away from the red hot surface with a few colorful hues, as well as some tarnished ugly shades. After threading the tubing, I didn't like the oxidized patina at all. So I remembered Barkeeper's Friend which contains oxalic acid and it almost removed every single trace of heat damage with a soft scrub sponge using the finely woven abrasive side. If I'd put in more effort it might have restored entirely like new.
Bar Keeper's Friend "Once tried, always used". Good slogan.
http://www.barkeepersfriend.com/

bob800 - 7-7-2013 at 18:13

Is it OK to soak standard taper glassware in concentrated NaOH/EtOH mixture, or will it ruin the ground glass joints? I thought I'd read that before but I couldn't manage to find any threads mentioning a problem...

Antiswat - 9-7-2013 at 02:17

i wont reply to everything as it would just get exaggerative
a question however..
bob800: i dont think you want fine glasspieces to be in contact with NaOH at all, really.
BUT however if you manage to keep the 'flow' of NaOH solution very even i dont see much could happen
whats it for anyways?
infact the ground glass joints could potentiall be ruined by the NaOH, might or might not
im not sure.. if you have a broken piece of glass joint soak it in the solution and see

sargent1015 - 9-7-2013 at 17:27

Quote: Originally posted by bob800  
will it ruin the ground glass joints?


The quick answer is yes, it will ruin it. However, for short periods of time (20-60 minutes) it will not do any noticeable damage.

In my lab, we scrub and dissolve almost all the junk on the glassware and then place them in the "base bath" for rather short periods of time. We do this for any ground glass piece, so you could say this is a well tested method. If you forget it in the bath overnight, you may have problems, but I have accidentally done it before with heavy walled round bottoms and no noticeable damage has befallen them.

bfesser - 9-7-2013 at 18:03

<em><a href="search.php?token=&srchtxt=cleaning+glassware&srchfield=subject&srchuname=&f%5B%5D=all&srchfrom=0&filter_distinct=yes& ;searchsubmit=Search">Omnia prius dicta sunt!</a></em>

[corrected from "dictum est"]

[Edited on 7/15/13 by bfesser]

sargent1015 - 9-7-2013 at 19:07

Well, guess it's about time to close this thread? I like the compilation, unless you are grabbing posts from in here for your new sticky thread :P

bfesser - 14-7-2013 at 09:46

<em>I see no reason</em> to close it. I just wanted to point out that there's a lot already here for anyone who knows how to find it. There's always room for addition.

annaandherdad - 15-7-2013 at 11:51

I've had trouble with silver stains on my lavatory. I don't have a sink in my (garage) lab and so have to use the bathroom lavatory. The stains seem to come from traces of silver nitrate, that perhaps via the chloride eventually turn into silver. Scrubbing does not help. I would use nitric acid, except it would attack the metal fixtures around the drain. I've been thinking of piling up sodium carbonate in a mound around the drain, to protect it when the nitric acid drips down, and then scrubbing the silver stains with the nitric. If I do this, I will rinse in distilled water, to avoid chloride formation and to flush all the silver down. Any advice for alternatives would be appreciated.

bfesser, I think it should be omnia prius dicta sunt.

bfesser - 15-7-2013 at 12:38

A few days ago, while preparing wood sash windows to accept <a href="http://en.wikipedia.org/wiki/Glazing" target="_blank">glazing putty</a> <img src="../scipics/_wiki.png" />, I spilled a large volume of oil-based primer on my hands. Unfortunately, my brother didn't have any hand cleaner at his house, but I did find a box of washing soda (Na<sub>2</sub>CO<sub>3</sub>;) under the kitchen sink. I wet my hands under the tap and scrubbed them with the coarse powder, then rinsed thoroughly. The base completely removed every trace of primer. The skin felt slippery afterward; if I recall correctly this is caused by the moderate/strong base disrupting cell membranes.

So, if you're willing to put up with a little pain, sodium carbonate and water will clean many stubborn residues off your hands (and strip off a bit of epidermis).

Antiswat - 15-7-2013 at 12:44

this is because the fat in your hands are converted into glycerine and other things (soap?)
NaOH + animal fat is how you make soap, the glycerine is what makes it so slippery, this can be removed quickly with a acid wash, otherwise it might take many handrubbings to remove that effect, paper should do the job also, but yes if you have something release from beneath the skin, then it would make sense to push out whatever stuck to the skin
one thing
dont play around with bases, as you will eventually end up with no fat around your hands (also youre wrists)
you will get very bony hands
plausible a way to loose fat extremely fat, but im a bit worried if this could go deeper in your body and be very hard to wash out, etching your body apart?

bfesser - 15-7-2013 at 12:50

That sounds erroneous to me. People had been using washing soda for laundry for a long time before modern detergents, and much of that washing was done by hand. Some people (like my weird brother) still use it, although more often in an automatic machine. I'm not recommending constant exposure to concentrated sodium carbonate, but an occasional cleaning shouldn't do irreversible damage. Have you been reading too many MSDS? :P

Antiswat - 16-7-2013 at 18:27

not really
if SO3 fills my room i dont run, i fix it (;
actually demonstrated to my classmate how you can detect highly basic liquids - by taking some on your finger and rubbing

infact for higher order christian believers who wanted to make others think they had a sign from god, they took on a piece of cotton a concentrated solution of NaOH and made a cross on their arm etc.
an hour later after severe itchyness the skin would have sunken down abit, where the shape of the liquid would appear
this has been done accidentally also, a guy i know who worked at a factory had a tiny droplet of it land on his sock and somehow get in contact with his skin, he didnt care about the minor itchiness, when he went home he found out he had a small 'hole' or crater in his skin

if any MSDS would be worrying to me, then it would be nicotine, caffeine and dichromates

Antiswat - 16-7-2013 at 18:50

various stains, increasingly more and more messy
so i have this 250 mL erlenmeyer flask on my table in the kitchen, its covere with aluminium foil, not completely airtight, but more than enough, or so i thought
i have gotten some very very VERY interesting perfectly round circles on the table, that is pretty close to completely white, im considering this could be the bleaching magic of NO or NO2??
the flask contains PbO and PbO2 set to react with HNO3 btw
i was so stupid to after seeing these circles move the flask and let it stand, thereafter seeing circle number 2 move it and set it on my table AGAIN
good job.
decided it wasnt time for sleeping tonight, so i got back up and went to my kitchen to clean up etc.
why not try to remove the stains?
so then i figured out that KMnO4, thereafter added dilute H2SO4 and finally zinc powder (900 mesh) would do a good job on a wooden table
no.
i guess its time for a picture by now
starting point
http://imgur.com/TN6n4GP
NOW.
http://imgur.com/Lv75Qo9

now that i get to think about it, KMnO4 + H2SO4 dilute would give H2MnO4, or HMnO4, which would then go into MnO7 (or doesnt this happen with dilute H2SO4??)
anyhow seemingly reacting with the wood putting in a pretty annoying amount of MnO2

the stain was much more violent some time ago than it was now when i took the picture
doesnt look good anyhow
i put on some NaHSO3 and ascorbic acid as they have shown to remove MnO2 pretty well, but this looks like a new level of intensity and pretty overall de-cleaning
if anybody survived a situation alike this please give some advice??


edit: update
seemingly this approach is if kept wet during all times and not leaving it to settle actually useful, tho i still have a faint stain of MnO2 deposited in the wood
of what i see its no longer bleached so horifically, which is good, but im not entirely sure, perhaps KMnO4 H2SO4 and Zinc is useful for this anyways?

[Edited on 17-7-2013 by Antiswat]

zenosx - 24-12-2013 at 19:44

Not delving into the chemistry I will just throw out there that the white circle looked a hell of a lot better than the bloody looking stain After cleaning there Antiswat :P

Sorry couldn't resist :) Have you tried the tried and true NaOCL yet on the stain?

Sorry if this was already mentioned, I skimmed of the whole thread, but didn't read all of it.

Zyklon-A - 23-4-2014 at 13:17

How can I remove a nitric acid stain? I spilled some fuming nitric acid on my fingers, is there a way to get the yellow stain off?
Never mind, I found this http://www.sciencemadness.org/talk/viewthread.php?tid=22590 Still didn't really answer my question...

[Edited on 23-4-2014 by Zyklonb]

Crowfjord - 23-4-2014 at 13:57

If I recall correctly, nitric acid stains skin by nitrating the phenylalanine and tyrosine residues in skin proteins. As such, you pretty much just have to wait for that portion of skin to die and peel off. Just another mark of a chemist...

Antiswat - 25-4-2014 at 12:11

speaking of marks of a chemist: be very very careful with pyrotechnical compositions containing phosphorus..
KMnO4 + red phosphorus behaves SOMEWHAT alike with chlorate/perchlorate, although when i tried it, it shot a gigantic shower of phosphorus, resulting in very deep burns in my skin
on a sidenote: 70% HNO3 is enough to nitrate skin, or as crowfjord enlightened us with: phenylalanine and torosine

also zenosx: yes i.. i tried everything
styphnic acid however, quite staining aswell..
however its not much of a problem as i had a fire in my appartment and entire kitchen was ripped apart and exchanged with a nice new kitchen which seems to have a table alot more stain-proof

Bert - 25-4-2014 at 12:44

That kitchen fire was the ULTIMATE STAIN REMOVER! There are days I fantasize about cleaning the floors like that ...

Keep some Copper sulfate solution around for those Phosphorus debridement moments?

There's almost nothing a professional pyrotechnic manufacturer USES red phosphorus for- Pull/scratch igniters are about all I can think of.


Zyklon-A - 25-4-2014 at 12:50


Antiswat , Ouch! That's way worse than a little 98% nitric acid. My burns no longer hurt, and the stain is almost gone. My finger nail is still orange, I doubt that will go away until the entire length of nail grows back.:mad:
I still have a deep scar, which doesn't look like it's going anywhere either.


Speaking about Marks of the Chemist!

[Edited on 25-4-2014 by Zyklonb]

Antiswat - 28-4-2014 at 08:37

oh yes.. seen that video.. never felt really safe with thin glass in my hand.. even if you try to stop your hand your reflexes must be subliminal to avoid getting for example a broken glass thermometre shoved through your hand.. you sometimes need to push quite hard to get glass through rubber stoppers

however the phosphorus burns was just like.. 0.1mm burn hole size, but still very deep.. many times deeper than its width, not to mention the P2O5 would create phosphoric anhydride from the water in your body.. quite the combo

Texium - 10-5-2014 at 13:23

Ok, bit of a problem here. I melted some indium in my ceramic crucible… forgetting that it wets glass. Now I have little bits of indium all stuck to the bottom of the crucible. Any ideas on how to get it out?

Edit: Never mind. I feel silly for asking now. I just put some HCl in there and that cleaned it up just fine. I guess I thought that indium was less reactive than it actually is for some reason.

[Edited on 5-10-2014 by zts16]

hyfalcon - 11-5-2014 at 07:43

I have a similar problem on porcelain tile. On a side note, how would one go about removing picric acid stains on counter tops?

Antiswat - 25-6-2014 at 11:56

i dont think there are any solution to that, hyfalcon..
same shit with styphnic acid solutions
perhaps just pour it all over the table and get a nicely fluorescent table

HeYBrO - 30-6-2014 at 15:57

Quote: Originally posted by woelen  
A very good way of removing such brown stains is rinsing with an acidified solution of sodium sulfite or bisulfite. Stained glass becomes clear again at once. Equally well works a solution of 1% H2O2 in dilute acid. Both solutions reduce the brown MnO2 to colorless Mn(2+), which goes into solution at once.


Interestingly, I've found that with MnO2 that has been deposited on to glassware, some 3% H2O2 works actually quite well for dislodging most of the MnO2. seems its to due with the decomposition and the micro bubbles which are formed.
However, it remains insoluble and it not as efficient as acidified hydrogen peroxide as there is usually a little left which has to be scrubbed.

[Edited on 30-6-2014 by HeYBrO]

Really Nasty Old Glassware

Texium - 13-7-2014 at 16:48

I've been fortunate enough to have recently obtained a very large amount of nice assorted glassware, practically tripling my amount lab equipment (which was not very much before this). The downside is that it was stored in an old non-climate-controlled shipping container for around 8 years, so it has all manners of filth on it, plus some pieces that still have residue remaining from the previous owner.

I was thinking of cleaning it with sodium hydroxide and then sulfuric acid, but I wasn't sure exactly what concentrations of each I should use, or if I should use different chemicals entirely to get the job done.

The possible stuff on the glassware includes generic dust, rodent poop, dead insects/scorpions/small animals, bits of paper and cardboard, grease, and some unidentified organic compound residues on some of the pieces.

gdflp - 14-7-2014 at 20:23

Hexavalent chromium and concentrated sulfuric will most likely attack everything but for that much glassware it's expensive and dangerous. I would try a saturated solution of an alkali hydroxide in 95% ethanol or isopropanol. Dont leave it in too long though(check on it once every few hours to see how it's progressing), or soak ground glass joints as it will slowly dissolve the glass and may effect the fit of the joint. If it's still not clean, try a soak in some concentrated hydrochloric or sulfuric acid. Acetone tends to be a good solvent for many stubborn organics.

Texium - 16-7-2014 at 04:57

Alright, great, thanks for the input! I'll take all of that into consideration when I start working on it.

Ascaridole - 17-7-2014 at 16:33

Ha so that's where your cool unknowns are coming from... 6M nitric is good for organics and inorganic crap. That's what I use at work and home to keep my analytical glass in good shape. Chromic acid also suffers from adding chromium contaminants to your glass, not always a problem but in analytical chem not fun. Also synthetic glass soaked in a base bath should be cautiously used with high vac. One or two tratments won't ruin it but repeated base baths will etch the surface enough to make it and implosion hazzard. This is of significant concern with used glass as you never know if the previous owner base bathed them.

Texium - 17-7-2014 at 19:54

Yeah, I have more unknowns to post on that thread once I unpack them, probably tomorrow. I started cleaning the stuff today, and just went with sodium hydroxide for most stuff, and sulfuric acid when that didn't work.
Normally when I clean my glassware I won't use sodium hydroxide, so I don't think it would be anything to worry about, especially because this stuff is all from the 1950s at the latest, and it's really heavy duty. The filtering flasks are practically twice as thick as they make them nowadays.

Cleaning carbon from Büchner funnel

Texium - 28-7-2014 at 15:35

Well, I feel like I made one of those silly mistakes that inexperienced people make when they have fancy equipment to play with.
I was filtering the suspended carbon out of an iron sulfate solution using a Büchner funnel and very sensitive filter paper, but the paper didn't fit exactly right and now I have little particles of carbon stuch in the ceramic part of the funnel. I tried reacting it with conc. sulfuric acid, but that didn't seem to work very well. Any suggestions are much appreciated, thanks.

Oscilllator - 28-7-2014 at 19:04

Quote: Originally posted by zts16  
Well, I feel like I made one of those silly mistakes that inexperienced people make when they have fancy equipment to play with.
I was filtering the suspended carbon out of an iron sulfate solution using a Büchner funnel and very sensitive filter paper, but the paper didn't fit exactly right and now I have little particles of carbon stuch in the ceramic part of the funnel. I tried reacting it with conc. sulfuric acid, but that didn't seem to work very well. Any suggestions are much appreciated, thanks.


The best advice I have is just to deal with it. Carbon will not react with just about anything you are ever going to put down that funnel, so the only issue you are going to have is a cosmetic one. I have heard that chromic acid will clean Carbon stains, but I have been unable to verify that for myself and besides, dichromates are hard to get and toxic. I personally have a number of flasks that have small flecks of carbon stuck on them.

gdflp - 29-7-2014 at 05:25

Quote: Originally posted by Oscilllator  
dichromates are hard to get

I always hear this, but I can never figure out why. Are they difficult to source in Europe? I live in the US and I know of four sources where you can easily and cheaply buy a pound of dichromate.

Zyklon-A - 29-7-2014 at 05:36

I sold him 100 grams of potassium dichromate, a few months ago, so he probably still has some.
What about nitric acid, wouldn't that get rid of carbon?

[EDIT] gdflp, How cheap for you'r dichromate source?
I bought a pound for nearly $30.00 (including shipping) and wouldn't really call that 'cheap'.

[Edited on 29-7-2014 by Zyklon-A]

gdflp - 29-7-2014 at 07:42

I would expect pottery grade to be good enough for cleaning, and Seattle Pottery Supply and US pigment both sell it for $12/pound. Elemental sells lab grade potassium dichromate for $13.93/pound. With shipping for that one item it might be $10, but if you combine it with other things, it doesn't need hazmat shipping so it's not that bad.

Texium - 29-7-2014 at 12:02

Alright, well, I'm glad that it shouldn't affect it. I do still happen to have most of that dichromate that Zyklon-A was referring to, so I'll probably try cleaning it at some point just for the sake of having it look nice. :)
It seems like nitric acid would get rid of it too, since conc. sulfuric is supposed to, but I don't have any.

[Edited on 7-29-2014 by zts16]

Texium - 10-8-2014 at 13:28

Today I went ahead and cleaned the Büchner funnel by pulling chromic acid through. It worked wonders, leaving it looking as good as new. Afterwards I pulled plenty of distilled water through to make sure and flush out all of the hexavalent chromium, and disposed of the stuff in my hazardous waste bucket. Definitely would prefer to not work with that stuff, but it really works. Thanks for the suggestion.

HeYBrO - 25-10-2014 at 14:34

Quote: Originally posted by zts16  
Today I went ahead and cleaned the Büchner funnel by pulling chromic acid through. It worked wonders, leaving it looking as good as new. Afterwards I pulled plenty of distilled water through to make sure and flush out all of the hexavalent chromium, and disposed of the stuff in my hazardous waste bucket. Definitely would prefer to not work with that stuff, but it really works. Thanks for the suggestion.

Did you reduce the chromium before you put it in your bucket?

Texium - 25-10-2014 at 14:58

Yeah, I did. I just let some aluminum foil soak in it until the solution all turned green.
I really hate working with hexavalent chromium, but sometimes it's the only thing that can get the job done.

[Edited on 10-25-2014 by zts16]

blargish - 25-10-2014 at 15:51

I can second that. I had a mortar that had some carbon/organic stains on it that did not want to come off. However, I dropped in a couple flakes of CrO3 with some sulfuric acid, swirled around with the pestle, flushed with water, and the thing looked as good as new; pretty crazy. However, like zts said, hexavalent chromium isn't the best thing to be dealing with.

I also remember seeing a youtube video where a guy cleaned a beaker covered in organic gunk by adding to it a combination of an Fe2+ solution and 30% hydrogen peroxide (Fenton's Reagent I think), letting the resulting radicals from the reaction oxidize the organics. I have not done this myself, but in the video it seems to do a very good job. If I find the vid, I'll post it

Texium - 25-10-2014 at 16:01

Luckily for most organics, concentrated NaOH solution seems to work well enough. Burnt cinnamon caked onto the bottom of a flask was no match for it. The flask was sparkling clean after 15 minutes of soaking.

DrMario - 25-10-2014 at 17:59

For the absolutely most stubborn organic contamination on glassware (or siliconcarbide-ware), we use piranha (H2SO4 + H2O2) at 120C.

Obviously, that stuff will make a nice dent in your hand, pretty much like the famous (and unintentionally hilarious) graphic warns.




[Edited on 26-10-2014 by DrMario]

blargish - 25-10-2014 at 19:06

Here is the video (not mine) of the use of Fenton's reagent to clean organic contamination on glassware.

https://www.youtube.com/watch?v=rJik_EnmgM0

DrMario - 26-10-2014 at 08:03

Quote: Originally posted by blargish  
Here is the video (not mine) of the use of Fenton's reagent to clean organic contamination on glassware.

https://www.youtube.com/watch?v=rJik_EnmgM0


While my sense of wonderment was quite satisfied by that video, I must notice that the procedure is quite wasteful. The price of the beautiful H2O2 used in that demonstration was comparable to the value of the beaker.

The good thing about heated piranha is that you can use it to clean a lot of glass/ceramic/siliconcarbide-ware. The process is slower, but you only have to dip the glassware in piranha and leave it there.

The bad thing about piranha is that it tries to kill you. Painfully.

gdflp - 14-7-2015 at 14:33

I tried a different method of cleaning glassware today and it worked great. Afterwards I searched and found a mention in an old thread, but I thought that it would be useful info in this thread as well.

The flask, or whatever glassware needs to be cleaned, is filled with hot water, then some (I used ~20g for a 1L flask) automatic dishwasher detergent is added and the flask is kept warm on a hot plate. It doesn't need to be terribly hot, ~45°C is fine. Noticeable gas evolution begins almost immediately and, if the flask isn't clean after about an hour soaking, it is emptied and refilled with fresh solution. I'm guessing that this gas is mainly CO2, but I haven't tested it. The detergent has it's ingredients listed as sodium carbonate, sodium silicate, and enzymes, and is dirt cheap, about 1USD/lb. It's remarkably effective, and is much safer than using alcoholic sodium hydroxide, chromic acid, Piranha solution, etc.

The flask I was cleaning had polymerised tar from a failed Hofmann rearrangement, but I tried it on several other flasks with carbon stains and it removed all of them. I doubt however that it will be as effective on transition metal stains, but it's worth a shot. I have a beaker, stained with what I believe is some sort of chromium oxide, soaking in it currently, I will update later on the results.

ave369 - 14-7-2015 at 22:31

In my country, the "chromium mixture" (hexavalent chromium in sulfuric acid) is typically used for removing organic residue from glassware. And for stuff that does not react with it, the "nitrochromium mixture" is used, which is hexavalent chromium in concentrated nitric acid. The nitrochromium mixture should be handled with care and only used for inert stains: if it comes in contact with reactive organics, unpredictable consequences may ensue.

gdflp - 20-7-2015 at 10:17

So, it appears that the detergent was ineffective on the metal oxide stains, I'm not terribly surprised though. I did try it on some other organic tars and it worked great on all of them.

Antiswat - 26-8-2015 at 05:15

it is possible if you have iron stains in a beaker, running iron-iron electrolysis using a halide-salt the XxO/Xx would very carefully scrape off the iron stains, and possibly also this could be used for other stains that would react with halides / halide-ites (hypochlorite etc)

its also possible you could turn the glass beaker into a passive electrode with enough current, and maybe into a functional electrode with unrealistic amounts of electricity

actually about hexavalent chromium and ozone would be possible to form through welding in stainless steel, maybe dragging the air from stainless steel welding into a beaker could be used in a practical fashion??

chemrox - 26-8-2015 at 12:12

How much FeSO4/ml water is used to make Fenton's reagent Fe solution? I have seen a few different processes calling for Fe II solutions without adequate documentation as if there were ONE FeSO4 solution.

solitanze - 25-4-2016 at 07:58

At our college we use chromic acid for cleaning basically everything. For really sensitive work boiling nitric acid is used after the chromic acid treatment.

But in my homelab I'd rather save my nitric acid and dichromates for more interesting purposes. I've had good results with 30% HCl + calcium hypochlorite for removing organic tars/residues from my glassware. Be wary of the chlorine gas that escapes though.

Chemetix - 26-9-2016 at 01:21

My go to solution for cleaning glassware is a welding 'pickle' that has about 30%nitric 10%HF. Only gentle warming is needed to remove the most stubborn gunk; organic- inorganic, whatever. Take it from me, I'm a professional scientific glass blower.

After some 'pickle' treatment a cycle through the annealing oven at 585C gets just about everything off. I cant guarantee the glass will be perfectly translucent anymore, more often than not it's fine. But if you have contaminated the glass that badly with minerals that change the chemistry of the glass, then there's bound to be some damage done.




[Edited on 26-9-2016 by Chemetix]

Antiswat - 27-11-2016 at 00:04

lately i found out that if you have something sticky, an oil or maybe even worse PIB and you dont wanna waste solvents on it, you can simply rub some dry powder onto it, in my world calcium carbonate is what is at hand, works well and also gets all of the grease off glass as well, the concept is simple..
a sticky material will remain sticky until its stickyness is absorbed by something dry, such as paper or another dry material, if the powder added is more susceptible to absorbing the "stickyness" than for instance the glassware you can rub it off easily
i avoid using flour because its a mess to wash off

on a pedantic sidenote directed Chemetix; be very careful with fluoride and fluorine compounds, they are bioaccumulative, approx 50% consumed stays in body to then cause chronic poisoning

pneumatician - 18-3-2017 at 09:32

hi, I distilled various times tap water and the flask get cloudy.

HCL only remove the limes but the glass remain cloudy, fluorides?

acid niter & sulfuric alone don't work.

no now I don't have cromate, HF... maybe piranha at room temp with h202 at 3%?

[Edited on 18-3-2017 by pneumatician]

Removing Carbon Powder from Glass

JJay - 5-8-2017 at 23:25

I recently ran a reaction that resulted in a small but extremely dark and persistent mass of very finely divided carbon. When cleaning, I made the mistake of washing it into some other glassware. It sticks to glassware, and it doesn't wash off with water. The only two methods I have found for removing it are scrubbing and piranha solution, and it is fairly resistant to piranha solution. I can't possibly scrub every surface that it's touched, and I don't want to have to handle the large quantities of piranha solution that would be required for removing it.

Does anyone know an easy way to remove finely divided carbon from glass?

unionised - 6-8-2017 at 00:43

The carbon may be sticking to grease on that glass, rather than the glass itself.
Washing with a strong base may well work.
Sodium hydroxide in wet alcohol sometimes does a great job.
(Mix about 5 g NaOH, 5g H2O let it cool for a minute or two and then add 90 ml ethanol)

Chemetix - 6-8-2017 at 00:53

There's not much better way to clean organics off than taking it to 400C, ok that's not easy for most ovens. But maybe a heating torch like this:

lpg-propane-heating-torch-500x500.jpg - 23kB

is one of the tools that is good to have on hand to burn off organics.

I use one to flame anneal borosilicate glassware and it will soften the glass at near full power ( depending on size and thickness of the glass) so going easy would be recommended.

JJay - 6-8-2017 at 01:10

I guess I might try burning it off with my blowtorch. I have a feeling that will be slow going, though.

Texium - 6-8-2017 at 07:22

Chromic acid would probably work, but that of course is a matter of last resort. I would recommend trying what unionised suggested before you do anything else.

SWIM - 19-10-2017 at 08:11


OTC glass and tile cleaners can be useful for various glassware deposits.

Lime scale removers (I use Lime-Away) work well for hard water deposits and toilet bowl rust stain removers (Rust Out is a good one) work for iron oxide and some other metallic crud.

I've also had good results with commercial oven cleaners (I use Viking brand) on carbon deposits and blackish polymerized gunks.

These products are not only convenient to get, but they're engineered to be safe for plumbing and relatively safe for the environment so you can just flush them down the drain. No depleting your chemicals stockpiles or adding to your waste disposal/recycling woes. This also applies to the earlier post about dishwasher detergent, an Idea I'm looking forward to trying.

I used to get GREAT results with OTC barbeque grill cleaners, but those have been reformulated(at least in the US) and although they sort of work, they don't have the same kick they used to. (Small wonder, The one I used to use had dichromates in it :o)


j_sum1 - 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.

Melgar - 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.

CharlieA - 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).


Sulaiman - 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.

Cleaning a RBF

CobaltChloride - 16-3-2018 at 03:44

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?

j_sum1 - 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.

Melgar - 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.

wg48 - 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.

happyfooddance - 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.

JJay - 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]

Mr. Rogers - 10-9-2018 at 00:54

Wash Bottles --

Why are wash bottles for certain solvents made from incompatible materials?

Every compatibility chart for polypropylene states it will be attacked by acetone, but this is a common composition for acetone wash bottles? I have to assume I'm reading something wrong or too far into this...?

[Edited on 10-9-2018 by Mr. Rogers]

CobaltChloride - 10-9-2018 at 01:37

I never saw any wash bottle made out of PP. All the wash bottles I saw were made of LDPE which is the ideal material for one because it reists acetone, alcohols and water. It is also very flexible so you can squeeze the bottle. Are you sure the wash bottles you are looking at aren't LDPE?

wg48 - 10-9-2018 at 01:53

Quote: Originally posted by Mr. Rogers  
Wash Bottles --

Why are wash bottles for certain solvents made from incompatible materials?

Every compatibility chart for polypropylene states it will be attacked by acetone, but this is a common composition for acetone wash bottles? I have to assume I'm reading something wrong or too far into this...?

[Edited on 10-9-2018 by Mr. Rogers]


My acetone arrived in what looks like a PP bottle and the last PP compatibility chart I read described its compatibility as excellent see: https://www.calpaclab.com/polypropylene-chemical-compatibili...

But then my real turpentine arrived in what looks PP but that chart described its compatibility as "Severe Effect" ??? I suspect it not pure turpentine as it was from the same seller that sold me asphalt as a water soluble black wood dye.

Edit: From the same site it describes the compatibility of LDPP and HDPP as "at 20°C-50°C: damage may occur.
Not recommended for continuous use" see: https://www.calpaclab.com/chemical-compatibility-charts/

Apparently I reading wrong too LOL



[Edited on 10-9-2018 by wg48]

Sulaiman - 10-9-2018 at 02:21

there is often a (recycling) resin identification code on plastic items
https://en.wikipedia.org/wiki/Resin_identification_code

wg48 - 10-9-2018 at 03:01

Quote: Originally posted by Sulaiman  
there is often a (recycling) resin identification code on plastic items
https://en.wikipedia.org/wiki/Resin_identification_code


Yes instead of guessing check the code.

The acetone is in a HDPE bottle. The real turpentine bottle has a triangle containing a "0", (no arrows) to the right is a "2" I suspect HDPE.

CobaltChloride - 28-9-2018 at 07:59

I found a nice way of cleaning oxidized stainless steel crucibles. The oxide coating is calcined and doesn't dissolve in aqueous acids. However, I was able to clean the bottom of my stainless steel crucible from oxides by covering the interior with a layer of ammonium chloride and then heating this with a torch until it started emmiting a lot of smoke and then letting it cool down. I did this five times, then I rinsed out the ammonium chloride. Much of the oxide coating had dissapered and I was able to remove the rest by just scrubbing with a brush and a bit of warm soapy water.

This procedure seems obvious now seeing as ammonium chloride is sold exactly for removing oxide coatings, but I didn't see it mentioned on the forum so I thought I'd share it. Now I don't need to buy another salt shaker for doing reactions with molten alkali :cool:

[Edited on 28-9-2018 by CobaltChloride]

pneumatician - 4-5-2020 at 10:21

I distilled tap water various times and the glass get a sticky white layer... not remoblable with nitric, sulfuric, chloridric...

monolithic - 14-8-2020 at 09:41

For anyone who cares, I found that Oxiclean (sodium percarbonate) works well for getting glassware sparkling clean. Mix with tap water, swirl around every now and then for a total of a few hours, then rinse with tap water followed by distilled water. Before I used Oxiclean I would always get water beading on glassware no matter how well I cleaned it with acid/base/acetone baths followed by distilled water rinses. Now I get absolutely clean glassware with no water spots, no water residue, and no water beading.

Apparently it decomposes into hydrogen peroxide, so you might be able to get the same effect with dilute hydrogen peroxide. I just find storing a tub of Oxiclean to be more convenient since you don't need very much (under 50 g) to make enough solution for a 1 liter flask.


[Edited on 8-14-2020 by monolithic]

1KEE - 4-10-2020 at 16:39

I've been having too much fun cleaning some rusty metal parts lately, thought I'd share my favorites.

Ultrasonic tank with hot (85 deg C) Alconox solution is one of them.... Works great on glass, works good on rusty and oily metal parts.

IMG_0788.jpg - 620kB

Added bonus, I've recently noticed that it removes rust, down to bare metal. Not sure if it's chemical or mechanical (from the ultrasonic) action. Here are some parts that, 30 mins ago, were completely covered in rust.

IMG_0790.jpg - 1007kB

Downsides are it makes a lot of steam, I run it in the bathroom. The hot and slippery parts are hard to handle (specially if glass). And have to keep stuff from touching other parts or the sides of the tank. I'm still trying to figure out a nice basket that's soft, and keeps parts separate. But hot Alconox solution in ultrasonic tank, great for cleaning glass.

Now for extreme cleaning. This is a stainless steel glovebox what we charge with sodium- or potassium- hydroxide solution, and heat to like 90 deg C. The solution goes though a filter and a 1000PSI pump, like a pressure washer

IMG_0753.jpg - 694kB
IMG_0756.jpg - 753kB

Cleaning parts from a sailboat diesel engine that's crusty inside with salt water deposits. It's a truly evil machine to use, the amount of steam that comes out is ridiculous. I'm running it outside until I figure out ventilation. The hot solution under high pressure is hard on gloves (and on hands under the gloves). Finding gloves that don't disintegrate is hard, plus I'd like to find something that insulates from the heat.

I would never dream of cleaning glass in the pressure blasting cabinet, things are slippery and the jet of solution will pop things out of your hand and send it flying. But good for rebuilding machinery, engines, turbines, etc.

EDIT: one more thing. I'd be very hesitant to use Scotch-Brite (the green or brown scouring pads) on glass. These have an abrasive that's pretty effective at scratching glass, making grime stick to the scratches next time, and weakens it.

[Edited on 10-5-2020 by 1KEE]

MidLifeChemist - 4-10-2020 at 18:51

Yeah, soaking it in dilute vinegar for 24-48 hours (scrub and repeat if needed) is my method of choice for any kind of alkaline earth or metal salts, and seems to work quite well.

Quote: Originally posted by JJay  
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]

Fyndium - 17-10-2020 at 07:50

Quote: Originally posted by monolithic  
For anyone who cares, I found that Oxiclean (sodium percarbonate) works well for getting glassware sparkling clean.


Similar product outside US is sold as Oxi Action by vanish. I've noticed the same effect recently when making perborate from it.

Quote: Originally posted by CobaltChloride  
I found a nice way of cleaning oxidized stainless steel crucibles.


At work (and at home too) I have used an acid paste that consists of nitric and hydrofluoric acid. It's the magic potion that makes stainless steel look fabulous and shiny, after it's been oxidized by welding, seasoning or other reasons. It's a bit more hazardous to handle, but as a paste, it fumes very little and avoiding breathing it and rinsing it well is good enough. It just eats the oxide layer off and you can pretty much see it dissolve as you spread the paste. I seldom cleanse my crucibles because they get that oxide layer back at instant when heated, and are pretty much passive after that.

MidLifeChemist - 17-10-2020 at 08:43

Since we are talking about glassware, I'll share my recent experiences..

Soaking in dilute vinegar seems to work well for copper salts deposited on my glassware. For Iron (III) precipitates stuck on my glass and funnels, vinegar worked not so well and I had to use dilute HCl, which dissolved it right away.

A little Sodium Thiosulfate took good care of any Iodine stains I had on glassware, but the damage the Iodine did to my metal spatulas looks more permanent.

The water in our new place is very, very hard. The first few pieces of glassware I washed were covered in white spots / deposits from the hard water. So now I'm starting to do a final rinse in distilled water, hopefully that cures that issue.

Well that's it for now, looking forward to reading about other people's glass cleaning adventures.

itsallgoodjames - 19-3-2021 at 08:29

Quote: Originally posted by Antiswat  
Quote: Originally posted by MrHomeScientist  
Quote: Originally posted by weiming1998  
Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.


I have an anecdote I'd like to add to this. A friend of mine was etching circuit boards on his back porch and ended up with a lot of ferric chloride stains on the concrete floor. He tried my oxalic acid on that, but it did not work to clear it up. The stain would seemingly disappear, but when the deck was rinsed it would show up again. I think concrete is too porous for much of anything to work well. He might have to resort to using my hydrochloric acid for the purpose it was intended - etching concrete!


I've also found that minor iron stains on glassware can be removed by a soak in hardware-store-grade HCl over a day or two.


i think your mate may have a serious problem.. tell him to cover it up (:
as of what i have seen FeCl3 goes into Fe2O3 over time and thats really a bitch to attempt removing.. i got a table stained with that stuff all over, to my luck its a smooth surface unlike concrete, where i can then use CaO + HCl method on it..
careful HCl etching (dilute?) and then sudden neutralization when wanted result is acquired might be the thing for him..
dont know how smooth concrete were talking about here tho

that last sentence sounded hilarious to me, no idea how tho..


I have a big patch of ferric chloride stains on my garage floor, as a reaction involving it boiled over around a year ago. I will not come off for the life of it, no matter what I try. HCl, H3PO4, CH3COOH, nothing works :(. I guess that will forever be a testament to secondary containment for anything that has the possibility to boil over...

(if you care, I was using it to catalytically decompose H2O2 to make oxygen for god knows what reason, but I didn't have the proper glassware at the time, so I used a thin necked funnel to add the H2O2, a glass tube for the O2 to come out of, a quark to hold it all in place and an erlenmeyer to contain the ferric chloride. I added way too much H2O2, way too quickly, generating tons of heat and gas, causing it to boil. Ferric chloride solution began to flow/spray out the funnel, falling on the floor and making a 6 foot diameter stain that won't come off.)

Antiswat - 19-6-2021 at 00:47

@itsallgoodjames thats odd, ive found H3PO4 working very well against iron oxide, but you do wanna scrub it while using it, sometimes 25%ish works better than 80%
you might just wanna paint the whole floor over instead, a bit of grey paint or maybe cover it all in vinyl
i got a bottle of iron chloride, i recall mixing some H2O2 into it and immediatedly the iron oxide cleared up, maybe H2O2 + H3PO4 would do something cool? maybe try running an oxy-acetylene burner on it to give it some carbon monoxide, and then dissolve the formed iron in acid
really concentrated H3PO4 should work if you leave it for long enough, maybe high pressure water cleaner would be a better idea

Hoffit - 19-6-2021 at 14:40

Quote: Originally posted by itsallgoodjames  
I have a big patch of ferric chloride stains on my garage floor, as a reaction involving it boiled over around a year ago. I will not come off for the life of it, no matter what I try. HCl, H3PO4, CH3COOH, nothing works :(. I guess that will forever be a testament to secondary containment for anything that has the possibility to boil over...


Complexing iron could do the trick. Some oxalic acid could do the trick I think. Commercial rust removers can give hints for other good complexing agents.

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