accelerated rusting?

[Tim Lamb]

How would one go about deliberately rusting a sheet of cold rolled steel?

My daughter has decided that the *must have* fireproof hearth under her new log burner should be a rusted sheet of steel she saw lying about the farmyard. Unfortunately it is not quite big enough and extending it by welding is likely to cause buckling and discolouration.

I can purchase sheet steel from our agricultural merchant but it is likely they will have tried hard to prevent rusting in store.

Presumably a detergent to remove any oil followed by??

I have spent battery acid, brick cleaner, hypochlorite (sp) bleach plus the usual domestic cleaning products.

regards

[Scott M]

Degrease it (fairly liquid, squirt of brake cleaner) and throw it outside. Shouldn't take long.

[TMC]

why not try local scrap or demolition yards?

regards

[The Natural Philosopher]

Now they used to do this to rally cars.. I remember seeing the rally garage I lived over take delivery of a brand new escort body shell that looked like it had been dredged out of the Marianas trench.."what is THAT?" I asked "oh, its just been 'left out in the rain' a bit'" was the reply, accompanied by a wink.

I THINK it was acid etched...in a bath, with possible electrolytic assistance..

Looks like for STEEL hydrochloric or nitric acid or ferric chloride..

I left a screwdriver on ferric chloride years ago.that for sure rusted it!

Brick acid is hydrochloric, so try that..

[Chris Hogg]

Salty water, or just a dusting of salt, and leave outside but covered so that the salt doesn't get washed away. Degrease it first. We live by the sea. Any mild steel exposed to the salty sea-air rusts _very_ quickly.

[Cod Roe]

I'd second that, I made the mistake of cleaning my cheap brickie trowel with brick acid to try and remove the residual mortar stains, that it did, but next morning it was also covered in corrosion.

[NT]

saltwater is best, just leave it immersed overnight

NT

[js.b1]

To rust...

- Strip all protective oil off (obviously do not buy Zintec coated)

- Heat with a blow torch or fire evenly all over

- Plunge into salt solution

- Leave out in the rain at 45-degrees if you want a multi-coloured patina.

It will take on a surface orange patina very quickly. Black millscale requires much higher temperatures.

To remove rust...

- Acetic acid solution (there are others, but this tends to be cheap)

- Do not leave in beyond shiny steel or you may find hey-presto you are losing thickness fast

- Acid etch & zinc passivation spray (may be combined or separate) to stop surface rust

The alloy of the steel matters if you want a certain patina etc.

[Martin Bonner]

As noted else-thread, brick acid (possibly with additional salt) will do nicely (after thorough degreasing). Don't forget the brick acid is just there to provide chloride ions and disrupt any solid film. The actual Fe -> Fe2O3 reaction requires oxygen from the air - so a thin film of the acid is what is required.

If trying other combinations, DO NOT mix the bleach with any of the acids!

[Andrew Mawson]

Tim,

I have a couple of sheets of 9mm in the yard that are about 8'x4' and have stood outside for about 6 years so have a 'nice rust patina' if she wants to look and see if they are what she wants. Just down the road from you.

AWEM

[PeterC]

Blood has the same effect, so 'degrease' it with an AG and don't bother with protection.

[Chris J Dixon]

No point suggesting Cor-ten steel than?

[Weatherlawyer]

I believe the first tanks used were made of that.

[Andrew]

Leave it under the pier down at Worthing for a few weeks.

Even stainless steel would (eventually) object to that.

Andrew

[Tim Watts]

I think it would object more to the pikies that would nick it that night...

[Andrew]

How about going around farms looking for old muckspreaders and the like parked up in the corner of a field. You might get some nice rusty panels from a bit of old agricultural kit. Something made a few years ago with panels thicker than bakofoil which may have lost all its paint but not actually motheaten ?. In Horsham we have long established haulage contractor who also hired out excavators and suchlike. They used to have a field next to Ifield station where old ruston-bucyrus stuff and similar was just abandoned. I think Les Searle was his name. He has (had) a traction engine that appears at the Dorset steam fest and elsewhere. Old fuel/CH tanks that have rusted their outside and are now being replaced by double-skinned plastic are another possibility. Old skips would be a nice source of thick rusty sheet metal.

Judging by the way rust developed on my shovel after clearing salt laden snow, could you just make up a 'tank' with some dpc sheet and four bits of wood or a few bricks and chuck loads of salt in and immerse the panel for a few weeks ?.

Andrew

[Andy Champ]

Good stainless won't rust in salt water. That's why they use it on boats.

Andy

[polygonum]

Wasn't there something about keels falling off yachts due to corrosion of stainless steel bolts? And lack of oxygen around the bolts.

Or have I got entirely the wrong end of the stick here?

[Dave Liquorice]

under her

about

Sorry only just spotted this thread. What does the spec say for the hearth? For our stove it has to be a constructional hearth 840mm square minimum and at least 125mm thick. And extend at least 150mm back and sides from the stove, 225 in front (300 if used with doors open and no spark guard.

Or is this steel just a decorative cover over the constructional hearth.

As for making cold rolled steel rust. I'd try a good degrease, engine cleaner "Gunk"? followed by a good was maybe using a mild abrasive (Bar Keepers Friend, Vim, Ajax?) rinse. Leave outside, it soon rust but do you really want rust or the blueing?

[Tim Lamb]

Decorative really. It's a timber garden shed and the architect has specified 2 layers of plasterboard let in to the floor to act as a hearth. The stove is about as small as they come:-)

She's happy with the cold rolled finish.

regards

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