Arthur Dent
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Rust on lab equipment
I just purchased a few second hand labware items this morning and among the stuff I bought were some very nice "Fisher" clamps and round flask stands
that were unfortunately heavily corroded.
So I filled a bucket with water and added a bit of HCl and dropped the clamps in. The rusted clamps slowly bubble away and it seems to make a dent in
the oxide, however, I was wondering if a phosphoric acid 5% solution (Scale Buster) would be better to rid myself of the rust?
Since this is a fairly dilute hydrochloric acid solution (3 or 4%) that my clamps are in right now, I don't think this will affect the metal itself
if I leave them in there for 24H, will it?
Robert
P.S.: I just can't believe that I just bought a Kimax 1000 ml ground glass neck erlenmeyer for 10 bucks! I love that place!
all this for 25$
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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bquirky
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Great Score !
I once fell into the trap of trying to remove rust with HCL ... ITS A TRAP!!! 
those chloride ions relly do get everywhere everything in my work area got corroded and the item i was trying to de rust rusted evan worse 
ive since found out that oxilic acid is much better for more permanent removal of rust but it takes a while.
[Edited on 15-1-2011 by bquirky]
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Random
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I would take them out of HCl and then put them in NaHCO3 solution. Leave them for few hours, if there would be later some visible corrosion, I would
use phosphoric acid. It is rust remover actually.
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Arthur Dent
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Thanks,
I removed my round flask stand from the HCl this morning. Nothing but clean metal. So as you suggested, I rinsed the clamp and dropped in a solution
of sodium bi for 2 hours. Rinsed it again and put the clamp on my hot stove element to dry it out and kind of "anneal" it.
It looks pretty good right now. If the surface rust comes back, i'll try the phosphoric way.
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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cyanureeves
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Rust Out works great for derusting and cleaning steel prior to nickel plating. it doesnt take much either and cleans lab glass pretty good too.i think
its sodium bisulfite.
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BromicAcid
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Rubbing the piece with oil afterwords will offer some form of future protection. Many stainless steel cleaners are mainly mineral oil in some kind of
light hydrocarbon medium (propane / butane / pentane / etc). The scrubbing removes the rust and the thin layer of mineral oil left protects it.
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bfesser
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Where'd you buy all that, anyway?
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cyanureeves
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iron out is sodium bisulfate and rust out is phosphoric acid and water. iron out is way cheaper.
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peach
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I spent a good hour or two dipping all of the parts on my clamp stand, and the clamps (from the 70's or so I expect), in sulphuric, pressure washing
them, scrubbed the entire thing with wire wool until it sparkled, then resprayed the base and put some new rubber on the jaws.
Took about one afternoons worth of work with hydrogen chloride before it was looking grubby again.
If you want it to stay sparkling, some clear lacquer might help. But that won't help if you're heating with flames on a regular basis or anything
particularly nasty gets spilt on it - solvents / strong acids / bases.
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Arthur Dent
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Quote: Originally posted by peach  | | If you want it to stay sparkling, some clear lacquer might help. But that won't help if you're heating with flames on a regular basis or anything
particularly nasty gets spilt on it - solvents / strong acids / bases. |
There are heat-resistant paints, like "Tremclad" matte black BBQ spray paint that could be used, but it is likely to smoke away if submitted to a
direct, intense flame.
But then the idea of "galvanizing" the metal with a very fine coat of tin, copper or zinc might be a good idea?
I'm tempted to try to electroplate something on the bare iron... mhhhh....
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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peach
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The eastern manufacturers do that all the time with those dirt cheap routers and radiators - chrome straight onto rusty iron.
You know your scraping the bottom the barrel when the chrome is bubbling and flaking new out of the box.
As I always say though, pay shit all, expect it to look like shit. So long as I can very occasionally cut a hole with the router I got with the
flaking chrome and rust underneath, it's fine. I've had a DeWalt DW626 (2300 watts), sold that (to someone in Austrialia) and kept
the flaky one (partly because I knew no one else would buy it).
You can indeed get high temperature paint for engine blocks. I think the cans at Halfords go to 400 or 500C, but there's one in the Toolstation
catalogue here that goes to 650C. 500mls of Pro-cote, £7.11.
In the spirit of Henry Ford, your colours choices are matt black and matt black. Enjoy them at your leisure. 
So long as you don't hit the paint directly with the flame, it should be fine.
[Edited on 17-1-2011 by peach]
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food
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Hi
I picked up a bunch of neglected clamps myself recently. Most are made of Al, but for the ferrous(?) pieces I took the rust off electrolytically in a
sodium carbonate bath. This works well. The clamp shown was pulled a little prematurely; as you see the jaw has lost less rust due to poorer
conductivity over the hinge.
What I'd like to know about is a magical way to melt away the scabby surfaces on some of the alumini*um pieces.
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peach
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You could try a dunk in NaOH or KOH to etch the surface off.
I did that with mine, going over them with a pan brush to knock the muck off, then gave them a scrub with wire wool, after copious rinsing with the
hose pipe.
Top tip: DO NOT leave unattended. 
[Edited on 22-1-2011 by peach]
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food
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I'll trial that when I get back to them. There are pieces in various states of ugliness, only a minority are really pitted.
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Arthur Dent
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Go away... rust, and never come back...
@ food: Wow! that's pretty nasty rust!
I bought another batch of old clamps, but they only had traces of rust, and the phosphoric acid wash took care of that in a jiffy.
However, my latest acquisition was this vintage but fully functional Fisher stirrer/hotplate, which had heavy surface rust on on the top. For that
situation, I decided to go with some ammonia-based soap and a small brass wire brush.
I was surprised at how effective it got the rust off as you can see, which revealed some battlescars like heavy pitting (this thing must have been
used with very corrosive reagents that splashed all over).
Anyway, the top still looks a bit grungy, but it's a hell of a lot better-looking than when I acquired it. Bah, only paid 50 bucks for it and it works
like a charm.
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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Arthur Dent
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Go away... rust, and never come back...
@ food: Wow! that's pretty nasty rust!
I bought another batch of old clamps, but they only had traces of rust, and the phosphoric acid wash took care of that in a jiffy.
However, my latest acquisition was this vintage but fully functional Fisher stirrer/hotplate, which had heavy surface rust on on the top. For that
situation, I decided to go with some ammonia-based soap and a small brass wire brush.
I was surprised at how effective it got the rust off as you can see, which revealed some battlescars like heavy pitting (this thing must have been
used with very corrosive reagents that splashed all over).
Anyway, the top still looks a bit grungy, but it's a hell of a lot better-looking than when I acquired it. Bah, only paid 50 bucks for it and it works
like a charm.
Robert
--- Art is making something out of nothing and selling it. - Frank Zappa ---
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food
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Nice. I picked up a used hotplate stirrer myself and the novelty still hasn't worn off. Right now I need to load it up with a flask of malt extract to
build up a starter for a beer. It's the right tool for that job as well.
Where the electrolytic cleaning fell down was on the chains on some of the clamps. I may yet see if stitching a bare wire through the links isn't too
much aggravation. Otherwise I'll could try the phosporic acid if I can dig any up.
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digitalemu
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Oxalic acid works great for rust removal.
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redox
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After you etching bath, use WD-40! WD-40 covers the metal in an oily layer that prevents rust. I cover all my metalware in it, it works like a charm
My quite small but growing Youtube Channel: http://www.youtube.com/user/RealChemLabs
Newest video: Synthesis of Chloroform
The difference between chemists and chemical engineers: Chemists use test tubes, chemical engineers use buckets. |
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azo
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85% phosporic acid will clean up rust but the surface will turn black.
Then it would need buffing.
painting with red oxide kills rust , that is why they call it kill rust.
regards azo
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