Treating rusty steel.

[Dave Plowman (News)]

I have some car bits which are rusty and no longer available new. Secondhand parts are likely no better. They aren't structural - they just hold the rubber seal to the sunroof. Don't even show. Too complicated a pressing to make new - or at least for me. I cleaned some down to bare metal, treated with Jenolite, sprayed on zinc rich primer and finished with chassis black. Some three years later they're rusty again. I've obtained some better ones but would like to protect them in the best way possible. Any sort of plating worth doing? Especially a home kit? Or any other tips?

[ericp]

Easy to copper plate the things. A handful of copper sulphate and a couple of AA batteries would do. (Unless copper sulphate is considered useful for terrorism)

Problem would be cleaning the things to plate.

[Andy Dingley]

Easy yes, but it will also _encourage_ corrosion. You're using an acid process (it doesn't work without a splash of conc sulphuric acid in there too) and this will lead to sub-plating pitting developing, eventually breaking through.

If you want to copper plate, your easiest approach is often to nickel plate it first. Try reading the Caswell book for advice.

Avoid Jenolite, as it's too dilute and although it cleans rust, it also corrodes the steel. Either use glacial phosphoric (hydroponics shop) or even better, a proprietary deruster with tannins added (usually opaque white, not clear or pink).

Mostly though, I'd look askance at the quality of your zinc rich primer. Try Davids 182 for a good one.

[geoff]

In message , "Dave Plowman (News)" writes

Chuck them up to me, I'll stick them in with my metalwork for plating

[Huge]

POR15.

[Dave Plowman (News)]

Just Googled on this and Rustbullet claim to better it. ;-) That's the problem with this sort of thing.

[Dave Plowman (News)]

That's fine but asking in a shop for a 'proprietary deruster' would likely get you something like Jenolite. ;-) Any brand names?

Can't remember what I used.

[The Medway Handyman]

Loctite do a product that apparently converts rust to something black, never used it, heard its good though.

[Andy Dingley]

If you ask at a sensible shop like County Industrial in Cwmbran, the price of a thimbleful of Jenolite buys you a gallon can of something white label made by the Ephraim Hardcastle "Victoria" works in Cleckheaton, as they've done for the last 100 years. It looks like milk, it turns rust black and it's cheap enough to dip a Landrover in it.

In Halfrauds, I think it's by Loctite in little blue bottles. Still white.

[Bruce]

Sounds exactly like Kurust.

[Huge]

Indeed. I've never used Rustbullet -but I have used POR15 and I'm very impressed with it.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "The Medway Handyman" saying something like:

Dirt cheap to buy the raw stuff.

[Peter Parry]

Firstly get rid of all the rust. If the size permits the best way of doing this is electrolytic de-rusting as this does not effect the bare metal.

If the items still have some paint on you may need to wire brush the piece several times at intervals of about 12-24 hours in the derusting process to get rid of all the poorly adhering paint at the rust edges.

After washing and drying you can use whatever undercoat you like followed by topcoat. As the electrolytic derusting gets rid of all traces of active rust the paint cover is much more effective than it would be on most chemically treated pieces where some rust nearly always remains and starts again after a few months (or less).

[geoff]

That's the phosphoric acid

got 5l of it here lying around

[Dave Liquorice]

Is that something akin to Kurust? I've had good results with that stopping/converting corrsion.

Obviously not that zinc rich or not in glavanic contact with the steel.

Drygalv does the business here. Ground off head of a bolt used as a gate latch has not rusted. Similary shed bought washers bolts drop latches on the trailer that is outside 24/7 and has been for a few years. Admitedly they are also "zinc plated" but we all know how useless that is when outside 24/7...

Drygalv has a couple of drawbacks: It is expensive (IIRC I paid about a tenner for a small 250ml? tin) and is rather soft as a paint but it does work.

[Mark]

agreed

I use Bondaprime, much favoured by the boating-fishing fraternity. This is a rusty _steel_ milk churn I painted with it some 20 years ago and its been outside ever since, never did get round to giving it a top coat. but a good test as to how good a primer is.

[Andy Dingley]

...and the rest.

[js.b1]

Get rid of rust...

- 3M Clean-n-Strip XT (purple) are great at getting a bright Sa2.5 finish with a cheap cordless drill

- Combine use with Loctite white milky stuff (goes black) to get into pores to help neutralise what you can't get to

Zinc protection...

- Galvafroid - pure zinc so truly protects, =A325 per tin that weighs like a neutron star, rubs off, requires blackfriars galvanising primer before painting

- Dinitrol - Lower zinc so lesser protection, more abrasion resistance, easier to spray-prime & paint

It comes down to how rusted and what final finish.

Frost's Restoration do 3M clean-n-strip discs and etch sprays if just surface corrosion, then primer (fill in imperfections), paint, polishing compound and wax after a few weeks.

Zinga (think that is right) is an improvement on Galvafroid, but the best is 2pk (or lesser 1pk) zinc epoxy primer at =A330-55. Colleague used 1pk zinc epoxy primer on a windscreen surround that had been wrecked years earlier by an windscreen removal tool in the hands of an idiot main dealer. No rust progression (or leaks) after several years, he also saturated the underside of the windscreen trim with 3M 08509 non-setting black butyl goo in a cartridge for a belt-n-braces backup.

[Adrian]

"js.b1" gurgled happily, sounding much like they were saying:

I asked more-or-less the OP's exact question of a supplier of both Zinga & Galvafroid. Their answer as to which was best?

In the context of used car suspension parts, cleaned up with power wire brush, they said... neither. Both of those require REALLY clean - freshly blasted - steel to give of their best. For this job, they recommended Rustoleum 769 primer.

[Cicero]

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Bead blasting (or maybe harsher abrasive) followed by powder coating.

Cic.