Rust Removal

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Ian_Rob

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There are lots of rust removal chemicals but what would be best to remove light rusting from 4 no. steel I-Beam sections? They are roughly 100mm x 50mm x 1.8m long. I could use a light abrasive disk but would prefer a chemical that removes the rust without scouring the surface. Any specific recommendations would be appreciated . Thank you.
 
For something similar, I made a 'bath' out of plastic sheet in a sort of box of cement blocks, big enough for the item, then used supermarket hydrochloric acid, diluted.
Left them for a few hours and then carefully washed off and primed. Nice surface to paint on.
 
1.8m is a bit of a challenge - I'd use dry Oxalic acid and make into a solution. I don't know the strength, start with a weaker solution (it makes disposal easier).

DownWests' idea of a bath made from construction polythene sounds good - but will need great care when you have cleaned the steel (I'd do it over the soil in case you spill the acid). Heavy duty rubber gloves and eye protection are de rigour.

I'd make two identical baths, one with acid and one alongside with water. Once the beam is clean transfer from the acid bath to the fresh water bath (to rinse). I would not want to carry an acid soaked beam very far.

Be patient, steel will be corroded by concentrated acids.

Jonathan
 
You could take the worst off with coarse Wet and Dry paper, or a scotchbrite pad, then use any phosphoric acid based 'rust cure/remover'.
 
Ian_Rob said:
There are lots of rust removal chemicals but what would be best to remove light rusting from 4 no. steel I-Beam sections? They are roughly 100mm x 50mm x 1.8m long. I could use a light abrasive disk but would prefer a chemical that removes the rust without scouring the surface. Any specific recommendations would be appreciated . Thank you.
Click to expand...

You should physically remove as much rust as you can. Chemical treatment to what's left if you must, but it isn't a magic short cut.
 
Thank you for all the helpful replies. The rusting is only light but I would like to get back to the bare metal whilst leaving as smooth a surface as possible. A variable speed grinder helps but it is still all too easy to indent the surface. I will start by seeing how much I can get off by hand with a Scotchbrite pad and depending on how effective that is, try some Oxalic Acid (which I happen to have) or something stronger if that doesn’t work.

Evapo-Rust sounds good.
 
A lot of proprietary rust removers are Citric acid based. I have used Hammerite gel as it sticks well, but you can make your own. Jenolite I think still uses Phosphoric acid as does Hagesan..and oddly enough so does Coca Cola.
They all work, but you need elbow grease and a wire brush or two and old rags for wiping off.
 
Alfie168 said:
A lot of proprietary rust removers are Citric acid based. I have used Hammerite gel as it sticks well, but you can make your own. Jenolite I think still uses Phosphoric acid as does Hagesan..and oddly enough so does Coca Cola.
They all work, but you need elbow grease and a wire brush or two and old rags for wiping off.
Click to expand...
Quite likely as phosphoric acid produces a very thin inert phosphate layer. I sprayed the inside of tubes making up the chassis of a car. No need to rinse off the acid in that situation. It will leave a light powdery coating if rinsed and left to dry. Easy to clean off loose material but it will rust again where the coating gets rubbed off. I'd just leave it wet if the I-beam was in a protected area somewhere out of reach.
 
You, perhaps wisely, don't mention what the beam is for, maybe a new mainsheet track on a foiling dinghy :)

Once you have the steel clean - it will immediately start to corrode, on a microscopic scale. You need to consider how you are going to treat the steel subsequently - there is little point in rust removal if you don't protect.

Because steel corrodes on a microscopic scale quickly galvanisers, pickle (with acid, as you intend, and degrease or grit blast, unusual, and then galvanise immediately. A local galvaniser said if you leave grit blasted steel overnight you can see the impact on the quality, poor, of the galvanising.

So once you have cleaned - you need to treat - pronto.

Now this is all hearsay - except I did have some HT steel galvanised, simply galvanised as is - so no treatment, at all (it looked like bare steel), and it took not a milligram of galvanising - which did not matter - I was simply looking at the effect of heat on an HT steel.

Personally and it depends on usage I would have the steel galvanised, if possible - I have never found other treatments, paint, epoxy, soaking in linseed and boiling etc - very effective. We have a galvanised steel platform as a 'sort of elevated/cantilevered car park built from galvanised steel - we live 200m from the sea - after 20 years - not a spot of rust.

Jonathan
 
I've used Bilt Hamber's "Deox" crystals in the past, but only on small parts. It works extremely well, leaving a light grey sort of "etched" finish. You'd need quite a lot of it to fill a container big enough to put one of those beams into:

Deox-C - Bilt Hamber

They seem to do it as a gel too, which might be a more viable option, though I haven't tried the gel:

Deox Gel Rust Remover (1kg)
 
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