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I'm hoping to use some scrap structural steel pipes and plates to build a large BBQ/Smoker, but they're all pretty heavily rusted. I've seen people in tutorials use both wire wheels and preparation discs to do this, but none have explained their choice.

They all seem similarly priced and all have the same description of their function! Ideally I'd like to select the one which least marks the underlying steel.

I'm currently choosing between just about everything in this category: http://www.screwfix.com/c/tools/cleaning-preparation/cat5990034

  • For rust removal I find flap wheels more effective than wire wheels - but I'm not a statistically significant sample. I'd be tempted to try electrolysis using a battery charger, washing soda solution and a sacrificial steel anode. – RedGrittyBrick May 4 '16 at 14:01
  • Wouldn't the anode need to be of similar mass to the amount of rust I'm removing? and if so, how would I work that kind of thing out - I don't want to start on it (by commandeering the bathtub) and then realise I need weeks and an enormous anode! – Martin KS May 4 '16 at 14:07
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    You're tempted though aren't you! – RedGrittyBrick May 4 '16 at 14:08
  • I am tempted, but I get the sense you might be trying to kill me ;) – Martin KS May 4 '16 at 14:12
  • He's not trying to kill you. But, just in case, would you mind updating your will so your executor will post the results of your attempt here? – Daniel Griscom May 4 '16 at 16:23
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None of the above?

It's structural steel, you can just leave it rusty (if it happens to be corten, the rust actually keeps it from rusting further...) This may lack Wife Approval Factor for your backyard BBQ, however.

Least marking (and least direct effort, dust, noise) electrolytic rust removal - submerge it in a tub of water, outside, with sodium carbonate (washing soda) mixed in. Connect a low-voltage DC supply to the thing you want the rust off of, and a sacraficial electrode. Polarity is - to the thing you are derusting, + to the thing you are sacrificing. Both should be in the tub, but they should not touch. Turn on the power, let it bubble (that's hydrogen, which is why you do this OUTSIDE, only, not inside.)

For mechanical rust removal when looking for effectiveness/speed rather than "least marking" I use a knotted wire brush in an angle grinder. Conditioning disks will probably mark a bit less and definitely work slower, IME.

  • Ha - look what @RedGrittyBrick commented while I was writing that. Keep it outside, not in the bathtub... The sacrificial anode mass (lost) would only be similar to the mass of RUST, not the mass of STEEL. If you can find something like a block of graphite to use as a sacrifice, it makes a bit less of a mess. Keep the connection to it above the waterline. – Ecnerwal May 4 '16 at 14:09
  • OK, so electrolytic removal is ruled out then unless I buy a paddling pool or another bathtub. I've seen The Martian, so knowing it's hydrogen rules out indoors! – Martin KS May 4 '16 at 14:12
  • Plastic storage containers, old plastic drums (my local "used drum vendor" has clean ones that were used for food products for $20) or dig a hole in the ground and line it with a plastic sheet... – Ecnerwal May 4 '16 at 14:14
  • How long would the electrolysis process take? I'm just trying to work out if I need to find somewhere out of the rain for hours or days... – Martin KS May 4 '16 at 15:40
  • Keep the power supply out of the rain, run wire (low voltage, recall) and don't worry about the rain otherwise. Time is variable on a LOT of factors - how much rust, the concentration of the solution, the amount of current you can supply from the power supply (I use an old, dumb 12V automobile battery charger.) Folks restoring cannon from sunken ships will take months at it, most things in my personal experience take hours or days, but those are tool-sized things, mostly. Citric acid and no electricity is another approach (just don't forget about it - unlike electrolysis, it can be overdone) – Ecnerwal May 4 '16 at 15:53
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There is a rust removal product called Naval Jelly. It is a gel product usually applied with a brush. It dissolves the rust and leaves a clean paintable surface when used according to the instructions. Then there is the option of media blasting which is probably the most common method for rust removal of large jobs. I'm not offering these as "the best" solution, but it will accomplish your task without the introduction of electricity.

  • I have always found this product very disappointing; I'd like to believe it does what it claims, but I have never found it to be true in practice. – Ecnerwal May 6 '16 at 13:28
  • Huh. I've used it with success on several projects. Of course, it's not going to remove anything other than the iron oxide. I typically use it on projects that have tight spots making any forms of mechanical removal difficult. – bigbull15 May 6 '16 at 18:01
  • It just occurred to me the real reason I used the Jelly. It easily portable to remote locations (ie. The middle of the woods). – bigbull15 May 6 '16 at 18:05

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