How to clean chemistry glassware | Hacker News Reader

How to clean chemistry glassware

chem.rochester.edu

102 pointsadrian_mrd110 comments

Ex-undergrad-assistant in a organic synthesis lab, here. I am extremely familiar with glass cleaning procedures, having done it nearly daily for one long semester.

Base bath is how you clean glassware.

The base bath was a _saturated_ solution of KOH (potassium hydroxide) in a 10-gallon PTFE (molded "teflon"). You knew it was saturated by the KOH precipitate at the bottom.

You take your "dirties", making absolutely sure they had no residual acid on them, and ever so slowly, ease them into the bath. 24 or 36 hours later, remove them and repeat with the next batch.

After a few dozen cycles, you have to change out the base for fresh stuff. For that, you needed a face shield, shoulder gloves, and extremely steady hands.

Tedious, dangerous work.

Yup, had this job as an undergrad, too, in a national lab on campus. Standard process was something like rinse in regular water, scrub with detergent, spray off with de-ionized water, 5-minute dunk in aqua regia, dunk in more de-ionized water, then alcohol rinse and set aside to dry.

Wore butyl gloves and apron and a face shield. Accidentally raised my hands above horizontal once and didn't notice a trickle of acid over the edge of the gloves. Next time that shirt came out of the wash the sleeves were shredded.

Our aqua regia bath was also about 10 gallons, but it was in a WW2-era fume hood and it looked like it was made of some kind of metal in a concrete shield, that had been partially eaten away. One time a cockroach the length of my thumb fell into the bath while I was working - I heard the splash, and by the time I turned my head to see what happened, it was mostly just exoskeleton. I quit that job pretty soon after that.

Nasty liquids that clean the glassware is one thing... nasty liquids that would dissolve the glassware (and you) takes it up another level. I was happy when I got past that part of my experimental career.

Heh. I never had the pleasure of working with aqua regia. I watched a grad student burn himself with it once. We were filling out incident forms for a week.

for anyone curious, this guy uses it all the time to refine gold, it's very interesting work: https://www.youtube.com/@sreetips

To save people looking it up, _aqua regia_ (wikipedia- 'literally "regal water" or "royal water"') is a mixture of nitric acid (HNO3) and hydrochloric acid (HCl) in a 1:3 ratio.

It was used by alchemists, as it can dissolve gold.

niels bohr dissolved the nobel prize medals of colleagues in it and left it on his office shelf during wwII - the committee recast them after the war https://www.aip.org/history-programs/news/invisible-prize

Yeah, we did this. Two big plastic - just polypropylene, I think - boxes under the main sink. One acid and one base.

After daily use for 4 years it felt very routine. Glad I don’t do it anymore though.

I used to love how shiny the glassware was after coming out of the base bath. Lovely!

I know nothing of chemistry in a professional setting. What happens to all the byproducts and stuff you use to clean? I assume you can't just dump everything into one big barrel and send it off to the landfill.

My lab actually did have 88-gallon barrels for waste; one each for aqueous waste, organic waste, and ether waste. Ether waste was kept separate because we produced a lot of it and because it had to be treated with preservatives to prevent the formation of explosive peroxides.

Anywho, the old base had to be (gently) neutralized with acid before being dumped into the aqueous waste barrel. This had to be done slowly because exothermicity and dissolution heat.

Iirc, the waste barrels were taken back by Sigma Aldrich, to be batched, filtered, and re-distilled into reagent-grade solvents. Circle of life.

The waste is sorted by type e.g. if it contains heavy metal salts versus nasty organics. Quite a lot of this is recycled. Heavy metal concentrates are cheaper to refine than fresh ore; quite a few labs sell their waste to companies that extract the underlying metals. Nasty organics are often incinerated, which renders them harmless.

There is an entire industry around optimally managing chem lab waste. It doesn’t go to the landfill unless it has been thoroughly processed for both value and toxicity. Industrial chemistry is a low-margin business, companies extract every bit of value from their waste stream that they can.

You need to wash the glass in a weak acid (1N HCL) after rinsing. Otherwise, the surface of the glass remains strongly basic and if you work with any base sensitive molecules, it can break them up pretty quickly.

why can't you siphon the base bath instead of having extremely steady hands

i'm also sort of surprised this treatment doesn't corrode the glass. i guess borosilicate holds up to things that would ruin soda-lime glass

You probably could, assuming you had ptfe tubing (we didn't) but then controlling the flow velocity is harder. Heat of dissolution is real.

ptfe tubing is cheap but i was thinking a borosilicate siphon

i don't think you'd have any heat of dissolution involved with a siphon

never done this tho, sounds scary

hate to be the one to prime the siphon

maybe prime it with water?

I've not run the numbers...but mixing saturated KOH solution with plain water could still be dangerously exothermic.

sure, but you can fill the drain bucket with enough water to keep it from boiling over

It's interesting to me how concentrated HF is just universally acknowledged as one of the 'big bads' of chemistry labs.

I've run into "Yes HF works here but SERIOUSLY DON'T" in so many different contexts and processes. Sounds like a lovely thing to keep a nice distance from!

It makes the list of Things I Won’t Touch https://www.science.org/content/blog-post/things-i-won-t-tou...

Looks like it’s actually the first “Things I Won’t Work With” article he wrote, which seems about right:

https://www.science.org/topic/blog-category/things-i-wont-wo...

When I was a PhD student, my group were given a lab next door to our main lab. During the clear out we found a bottle of HF at the back of a cabinet. Vividly remember us crouching down to look at it all saying “nope, not touching it!”. Department technicians, understandably, weren’t willing to take it off us. In the end I think our PI got the previous lab owner to deal with it.

I remember the story of the Australian student working with concentrated HF.

He was sitting at a hood and knocked the container over into his lap. About a liter.

He was rinsed off but eventually the pain become so bad he jumped into the university swimming pool and stayed there until EMS arrived.

They ended up amputating both legs. He died anyways.

Bad stuff. I never worked with the concentrated stuff.

Apparently it was a technician and it was 100-250ml. Scary stuff.

https://www.uvm.edu/cosmolab/safety_manuals/Fatality%20due%2...

weird - can't find anything from an australian source about this

It’s also unfortunately crucial to a number of different industries ranging from uranium and rare earth metal mining to semiconductor fabrication.

It’s the reason for many a superfund site.

I would work with all that stuff, but only remote controlled.

I guess one day this will be indeed standard, but as of today, (useful) robots that could do it, are way more expensive than humans ..

In case anyone else wanted to cut to the chase - as in, what is the most badass, dangerous, corrosive and potentially deadly cleaning method:

Hydrofluoric: Concentrated solutions of HF will remove just about everything from glass and will even etch the surface of the glass itself. It should not be used on calibrated volumetrics. HF causes severe, painful burns that do not heal well, and prolonged or intense exposure can lead to a very slow, painful death. It is not to be used by any students at Truman under any circumstances.

Fun fact: dissolving yellowcake uranium in HF is the first step to uranium enrichment.

It’s also used as a wafer cleaner in semiconductor fabs.

Using HF to clean glassware is a bad idea. And as long as you're doing that, you might as well toss some antimony pentafluoride in the mix.

Acidic peroxide solution is also known commonly as piranha solution. You can clean silicon wafer by dropping them in. Any organic residue is toast, however.

Sounds enticing for cleaning burned baking dishes! I tried with concentrated NaOH and that didn't work so I need more extreme solutions.

If you catch it before it's totally incinerated, Tergazyme/Tergajet is the way to go. Otherwise try either Citranox or Alconox (or the 'jet versions for low foaming).

If none of those three will touch it, it's probably not cleanable by anything short of piranha-class terrors. If they can touch it but don't get you all the way there, there's probably some combination of detergents and procedures that will do it, but it may take some serious effort to figure that combination out.

The issue is that ‘any organic residue’ includes any food you might happen to put on it afterwards, if any trace of the solution is left. Or, for that matter, it includes your entire body. This is an exceedingly bad idea unless you enjoy your food bursting into flames, then burning a hole through your stomach if you eat it.

That seems like a terrible idea on many levels. Will definitely make for some fun anecdotes though (assuming nothing goes wrong). Also - I don’t know if I’d want to eat anything cooked on a baking dish exposed to so many toxic chemicals.

I assume you’re not joking, but this was a major whoosh if you were!

Well, I was not. I keep thinking there has got to be a way to dissolve the black, caked on oil resins, and so far I haven't found a solvent that works. I tried the relatively harmless stuff found around a household; the more aggressive being the lye solution, brake cleaner, acetone, citric acid, muriatic acid (i.e. HCl but relatively weak). Sibling has a good point to try more heat, which should be easy to try since the object is stainless steel.

I don't know how baked on you're talking here, but we somewhat routinely end up with oily residue that's still in the sticky to moderately hard state.

Baking soda and peroxide cleans that shit off like magic. You should Google the exact procedure and proportions.

Edited to add: a single edge razor scraper is worth a try on stainless. The razor blade is roughly as hard as the substrate, so you won't gouge it too bad. Get the plastic Allway holders. The metal ones are garbage and, incredibly, the generic plastic ones are pretty inferior.

> I don't know how baked on you're talking here

Very :-). I'm talking about a pan accidentally left on the grill or in the oven for too long until it smokes. The residue is pretty much what you end up with when seasoning cast iron cookware, and is very hard and resistant to usual household chemicals. It's far from the oily residue that is removed easily with paint thinner or acetone.

Oven cleaner (Easy-Off heavy duty or similar), in a sealed plastic bag with the item in question, left for 24-48 hours. Rinse thoroughly with tap water, then DI water, then distilled vinegar, then tap water & DI water again. Works to strip cast iron, should work for similar gunk. Obviously wear appropriate PPE (long rubber gloves, follow all warnings on the oven cleaner, work in a well-ventilated area, the MSDS[1] is useful though all instructions should be on the label).

[1] https://www.globalsanitation.com/edit/files/sds/retail/easy_...

If the cookware is metal you can use electrolysis.

Car battery charger clamped with an electrode to sacrificial metal plate and an electrode to cookware; both hanging apart from each other in a bath of electrolyte made of water + sodium carbonate. Let it work for a day or so in a well ventilated area (it will create hydrogen gas).

I have found an abrasive works wonders, and is fine on stainless steel pans https://barkeepersfriend.com/products/

You could try the trash bin and not doing it again method.

Have you tried barkeeper's friend with a nylon scrubbie or steel wool? I've found that to be excellent, if labor-intensive, at returning stainless steel to like-new condition, even when dealing with oily residue that's been baked at 500 degrees.

Gotcha! I don’t mean to dunk on you… sounds like a cool project if you take appropriate safety precautions, but the possibility of accidentally creating some poisonous (or carcinogenic) substances seems pretty high. I’m far from and expert though.

I might have a low risk tolerance, but I would toss any cookware touched by, like, half of the chemicals you listed. Don’t want to find out the hard way that some nasty layer of something is slowly leaching into my food.

If you do move forwards with this, definitely write up your findings... "Removing burnt food with piranha solution without dying" will make a great blog post.

Ammonia vapor works great on burned on grease if the thing you are cleaning isn't damaged by it. Use it for my burner grates and drip pans, just put them in an enclosed container with some ammonia and let sit for a day or two.

I would try piranha before trying more heat as the piranha is less likely to warp or discolor the stainless.

If you know what you're doing the equation boils down to determining if the container's worth more than the piranha solution will cost you to make in time/money spent. https://drs.illinois.edu/Page/SafetyLibrary/PiranhaSolutions

Put it in the over and run the clean cycle. It'll get ashed.

If it's on stainless steel, why do you need to remove it chemically? Does a stainless steel scouring pad not work?

Barkeepers friend and elbow grease hasn't failed me yet, but in fairness I may not have hit the same issue as the GP.

Mechanical methods certainly work, but they seem like a copout. I would find a chemical solution more elegant/satisfying just for curiosity's sake.

Depending on what the material is, you can potentially clean it by burning it harder. Set your over to 'clean' and find out.

Oven cleaner is a better bet.

My granny salvaged some burned stainless steel cookware from trash by boiling them in vinegar.

A colleague of mine used it to etch carbon nanotubes, I think. Absolutely horrible stuff.

I always preferred a mixture of KOH and H2O2. Basic solutions of peroxides have less tendency to spontaneously detonate.

Using Alconox (mentioned on the page, and easily found on Amazon) is one my tricks when I absolutely need sparkling clean dishes or containers. Not the best choice for the environment, and too sudsy to use in a dishwasher, but amazingly effective.

Are you using one of these?

https://www.alconox.com/product/alconox/

https://www.alconox.com/product/alcojet/

Their sheet says "biodegradable" so was curious about enviro impacts from your vantage

Looking at the data sheets, seems to have phosphates in it, which are questionable for the environment:

https://en.m.wikipedia.org/wiki/Phosphates_in_detergent

> which are questionable for the environment

Our industrial chemicals are highly toxic and kill whatever exists near the runoff: "this has to be carefully regulated."

Our industrial chemicals are highly nutritious and cause spontaneous blooms of life near the runoff: "this has to be banned."

+1 to Alconox. That stuff is just amazingly effective. A little goes a long way, so if you buy a container, it can last you a long time.

No pirhana water, I'm sad.

https://en.m.wikipedia.org/wiki/Piranha_solution

No worries, NileRed has your s/back/weiner/: https://youtu.be/bO9rvqp49qg

Also, magic acid feels left out of this exclusive Christmas party: https://youtu.be/pWB7oGbd8Yo

Frustratingly familiar from my college days is the vagueness of these instructions. "Wear appropriate gloves." Such as? It is easier to write "wear butyl gloves." Even the MSDS for 6M HCl doesn't say "wear butyl gloves" it says "Select glove material impermeable and resistant to the substance." Like, duh. Is there a PPE lobbyist who prevents people from writing down concrete recommendations?

A good point, a very good point. Too many procedures or guides are ruined by being vague on some minor yet critical point. Probably obvious the the writer but not to the reader.

However I will note this guide specifically points out to use butyl gloves twice.

Because recommendations will vary by not only currently accepted practices, but also geographical variances in product availability. It's better to look at what you have on hand and cross-reference with up-to-date information.

Much like most people won't simply know how dangerous it is to mix Nitrile gloves and Nitric Acid. When things can melt your skin, it's always good form to verify safety info at the time rather than just taking somebody's word for it, no?

My 2 cents that is probably obvious anyhow

Nitrile gloves are quite useless against many common substances, including acetone, esters, acetic acid, and everything else with "acet" in the name. Aside from a few cases where nitrile works and others don't (some hydrocarbons, among others), there's usually something more protective.

At this point I was wondering what gloves to use with what chemicals. And found this document prepared by the ansell company.

https://research.usu.edu/ehs/files/ansell-8th-chemical-resis...

For non chemists just working with standard commercial stuff(Epoxy, UV resin, grocery store cleaning chemicals, and that's about it), various sites and ads give the impression nitrile is "The good default thing you should use"....

Good to know that's not always the case?

There's no one glove type that works for all substances & situations.

Can you get gloves made from PTFE? I feel those would be the closest you could get to an "everything" glove.

Ptfe film and tape is common occurrence. Just wrap it around maybe?

Nitrile is a fine default at home and in the lab if you make sure to change your gloves when they are contaminated. You can also double glove.

>Aside from a few cases where nitrile works and others don't (some hydrocarbons, among others), there's usually something more protective.

Good luck finding something that protects your hand from the fairly occasional DCM/DMF/name any org solvent drops/spatters/spills

What's best for, say, my scientific glass bong?

Seriously, what's safe and effective?

Use 99% isopropyl alcohol. Add in a teaspoon of table salt -- it won't dissolve in the alcohol and will act as a mild abrasive to help remove stubborn residue. Rinse thoroughly with water afterwards.

If you're really serious about your cleanliness, a desktop ultrasonic cleaner is also amazing for cleaning bowls and downstems. You can get them for a few dozen dollars from Amazon and the like.

Soak in 95% ethanol overnight and then everything comes off with an easy wipe if you can get to it. Definitely safe, but I’m curious if these other solutions dissolve completely without a wipe?

I can only get isopropyl alcohol to clean cannabis glass by quick and easy dissolution if I warm the glass and the alcohol beforehand. Warm 99% alcohol absolutely destroys cannabis waxes.

'Orange cleaner' is very effective in this case.

I make it by macerating orange peels in 95% ethanol.

Acetone, after removing all rubber seals, then rinse with alcohol and boiling water.

Isopropyl works well

Chemistry is an amazing science and we probably need a lot more chemists....

But I'm sure glad I don't have to go near any of this stuff!

Hard to believe there's any hobby chemists out there messing with mercury and stuff, handling most of these chemicals seems like something you'd only ever do for a huge salary or if you believed your work was going to save many lives.

As an organic chemist who became a software engineer, I’ll say that it’s more than just money (Or curing disease) that drives a lot of people. There’s just something inherently amazing about having the literal world supply of a compound that you made using your own hands (and the laws of nature). And in organic chemistry, there’s a bit of subjectivity and art too - designing compounds, designing a chemical route to synthesize them, etc.

That is pretty cool, it almost sounds like what drives ASM programmers, but even lower level than that.

It doesn't seem to be 100% computerized yet, people still talk about doing real experiments where they expect to find something new about what they're studying, as opposed to just finding their own mistakes or reading about other people's discoveries.

I'd imagine that's probably part of the appeal for some people, in tech so many of us almost never discover anything new that would be of interest outside that one specific project, except an occasional framework bug.

Why did you become a software engineer in the end? You speak very highly of chemistry (as a software engineer who's flirting with the idea of going into chemistry).

I once had to work with some thio compounds. Infamous for their god-awful vomit-inducing smell. A labmate used to have migraine attacks if someone was working with them , in the fume hood.

The glasswares, along with the spent disposables, gloves etc were dumped into bleach solution. Even after a full month soaked in bleach and whatnot, I could still smell the nasty odor from the beakers and flasks. https://en.wikipedia.org/wiki/Thiol

Why isn’t lab glassware, with few exemptions, a single use item? How can the human safety risks in cleaning, and the analysis risks from residual contamination be valued less than the cost of fresh equipment made of…glass. Really nice glass, but simply mass-produced objects made of silicon and oxygen. Just make some more.

The 1970s Muppet Show US television program had a recurring segment on “Muppet Labs” with a hapless lab assistant named Beaker given silly and dangerous things to do by his boss. These cleaning processes sound like a Beaker bit. But the Muppet Show was a comedy…

Because laboratory glassware is very expensive and that would be massively wasteful? Also, most labs that I have been in make regular use of custom made glassware. Most chemistry departments employ a glassblower! Also, for very sensitive experiments, you would most certainly want to clean even brand new unused glassware.

Glass is amazing for chemistry not only because it is chemically inert, transparent, has a high melting temperature, and is reasonably strong but also because it is easy to clean!

> How can the human safety risks in cleaning, and the analysis risks from residual contamination be valued less than the cost of fresh equipment made of…glass.

Because these things can cost hundreds of dollars apiece [1]. They're handmade, and many universities run their own glassblowing shops [1] so that researchers can have the instruments they need precisely tuned to whatever is required. Training to be a glassblower that can produce the required quality takes almost a decade [3], if you want more pictures on just how insanely complex a single piece can get look here [4].

[1] https://hooloodistill.com/products/borosilicate-glass-distil...

[2] https://www.uibk.ac.at/en/aatc/service/scientific-glassblowi...

[3] https://www.bath.ac.uk/case-studies/the-underrated-art-of-sc...

[4] https://penntoday.upenn.edu/news/inside-scientific-glassblow...

If you are working in a lab that needs that level of cleaning, then odds are that what you do with the glass when you use it is also dangerous. There is a reason that the stereotypical chemist wears gloves, goggles, and a labcoat.

Also, lab glass is more expensive than it looks. If you care about this level of cleanliness, then you likely also care about the precision of your glassware. And lab glassware comes in much more exotic and hard to make forms than beakers. You also might not be able to throw it away in the normal trash because it is contaminated with something hazardous.

You're also not buying your equipment from Amazon either. I do some very very laughable to even calling chemistry, but I don't trust the crap on Amazon. At. All. I'm only working with sodium hydroxide and some oils, but I was even hesitant about buying stainless still from fear of knock off aluminum coated crap sold as stainless.

For anyone wanting to play the home game thinking they can just have their supplies same day from Amazon, just don't

A lot of it is not mass-produced (https://www.latimes.com/local/education/la-me-caltech-glassb...). Even if you used brand-new pieces, for analytical work, you'd still need to clean them according to these procedures to remove residues from manufacturing, storage, and shipping.

Because a lot of glassware is not easy to clean and manufacture, like beakers, flasks and tubes.

A lot of lab glassware involves complex joins. Condensers and refluxers have tubes in tubes with edges that are not even accessible.

There may be reasonable arguments to use some of the cheaper glassware once. I know I have chucked glassware instead of cleaning it. Specially if I used it for something I never want near anything else.

This bit "but simply mass-produced objects made of silicon and oxygen. Just make some more." is so agonizingly wrong I feel compelled to comment.

Some of the more exotic items are custom-designed and hand-made, and are exceedingly rare. Backlogs exist. "Please, don't retire, keep making us glassware" problems exist in chemistry departments. Various articles surface about this particular problem every so often.

And, frankly, if people are taking this much time to clean the glass, it should be obvious to you that one of your priors is wrong.

Yeah, let's burn through $500 worth of glassware for every single freshmen's weekly lab class. We occasionally used flasks worth $300. Let's also make computers single use as well.

I did this on a small scale all the time.

Rather than running it in a 10mL round bottom, just use a 25 mL vial. You can fit a rubber septum and purge it. Magnetic stir bars are small enough to fit. You can add reagents using a syringe.

Then just rinse and toss after.

Quality glassware isn’t cheap because the ground glass joint has to be precisely ground to not leak. But if you don’t need a condenser or drop funnel, disposable vials work just fine.

A lot of lab stuff is single-use plastic. But that is more on the bio side, that wouldn't work for chemistry. And there the glass is simply too expensive, so you have to reuse it. It's also not just flasks but also coolers and e.g. distillation bridges. Those are much more complex glassware.

For most items you don’t need to do anything beyond a scrub and rinse. Others have pointed out that glassware is expensive and sometimes unique. Additionally, if you don’t need much product (eg. you’re screening reaction conditions), you can work with small disposable vials or even plates.

Do you wear glasses? Why don't you buy a new pair every day?

Nile Red got into a situation where some of his glassware was damaged by a reaction but mixed into his still good glassware. He decided to break it all to be sure!

That's another cleaning strategy.

https://youtu.be/tGqVMbAQhBs?si=FAve6HjtEd9rjbZv

Notably, his concern was not that the glass was dirty, but that it was literally breaking. As in, spontaneously spill a beaker full of acid on the table breaking.

The experiment he blames this on was using the beakers to contain hot plasma. The beakers came out looking fine, but probably suffered substantial thermal stress.

I find glass fritted filters specially problematic when you can't even see inside the fritt. Maybe it's just me but I'd much rather a Buchner funnel with appropriate filter media.

I really like the all-glass filter holders with the 24-40 ground glass bases instead of the gooch seals. The smelly rubber gooch seals seem to go to shit so quickly.

”...the use of chromic acid is not recommended.”

Whilst rightfully it's not fashionable nowadays, I can attest however that chromic acid cleans glassware remarkably well (once it was just about the only cleaner we used).

For the chemists here, I have a question I’ve always been curious of.

Would you eat/drink out of glassware that had been made “quantitatively clean”?

1 atom or molecule of catalyzator will given enough time render a reaction happy liquid inert. Sneeze at platinum near a hydrogen peroxide storage and within a week..

i feel like this could be a fascinating series of youtube videos targeting the "oddly satisfying" niche.

edit: should've known it would already be a thing :) https://www.youtube.com/watch?v=utBxdlN7YFI&t=9s

> lachrymator

One of my favourite words that I never expected to encounter in the wild!

"something that makes you cry".

At U we used a saturated solution of KOH in Isopropanol.

Finally got the dishes done properly today, thanks Rochester!

I came here hoping for a "dishes are done" reference

Reply on news.ycombinator.com