How should I treat exposed steel?

[BrentonSpear]

I am curently rebuilding a trailer and it has a bit of surface rust on it. I have just finished removing the metal floor from it and as a result grinded nearly all cross members down to the steel.

What should I use to prepare the steel ready for paint?

For the moment I have just hit it with some gloss black paint I had lying around.

Brenton

[Doughboy]

Not that I know much about metalworking but I would be inclined to use some sort of rust inhibiter...

Along the lines of galmet. It can be sprayed or brushed on and works well.

Pete

[Bodgy]

Provided it's bright steel and no rust left, I really like the bitumised paints. They are also soft, so that any metal you overlay has a bit of a cushion. Unfortunately it takes 2 weeks to fully dry and your chioce of next coats is limited.

Alternately Cold Gal, always assuming there's no rust

[Wood Butcher]

Use something like "KillRust Cold Galvit".

The paint contains stuff that inhibits the further development of rust and the galvanic components protect from future rust. Make sure that you give it a really nice thick coat on all components (including mating surfaces) before you put the floor in. Then slop some more on the weld areas after the floor has gone back in.

[BobL]

For the moment I have just hit it with some gloss black paint I had lying around.


Pity about that because you should have rust inhibited first. Now if you want to do it properly you will have to remove the paint. No amount of stuff you apply over the paint will fix this problem. The first bit of paint that chips (or any tiny holes you left unpainted) lets in the air and it is probably rusting as we speak!

A cheap rust inhibitor is dilute phosphoric acid, it turns red rust into iron phosphate (blue) and when it dries you can paint right over that. I would recommend stripping off the gloss paint and using a proprietary rust inhibitor and then some decent paint. That galvit stuff that wood butcher describes is also top stuff.

[Metal Head]

Hi,

Here is the info pertaining to the "GALVIT" stuff.

http://www.wattyl.com.au/Specifiers/AR/Products/ProductSearch/Product_Details.htm?Id=387

& here is the site for the "GALMET" stuff. There is also a FAQ section.

http://www.galmet.com.au/driver.asp?page=main/home

Regards
David

[journeyman Mick]

Once you've finished treating all the steel, consider putting in a ply floor instead of steel. Makes for a quieter trailer and guaranteed not to rust!;) :p . I've had a sheet of 15mm exterior hardwood ply in the trailer that I built more than 6 years ago and it's still sound. It should see out ten years and only gets a coat or two of decking oil every year or so). Glue it in place with a cartridge of sikaflex and a handful of rivets or teks. It will be a lot easier to replace than a steel floor too.

Mick

[ozwinner]

How should I treat exposed steel?

Take it to a movie, have dinner together, but it flowers.

Al :p

[bennylaird]

How long does it flower for?

[Rossluck]

Pity about that because you should have rust inhibited first. Now if you want to do it properly you will have to remove the paint. No amount of stuff you apply over the paint will fix this problem. The first bit of paint that chips (or any tiny holes you left unpainted) lets in the air and it is probably rusting as we speak!

A cheap rust inhibitor is dilute phosphoric acid, it turns red rust into iron phosphate (blue) and when it dries you can paint right over that. I would recommend stripping off the gloss paint and using a proprietary rust inhibitor and then some decent paint. That galvit stuff that wood butcher describes is also top stuff.

This is the best advice. (1) You unfortunately have to remove all of that black paint. (2) Wipe over with some rust remover (this neutralises the rust in the pits that you can't see) , clean it off, (3) hit it with a good metal primer, (4) then you can paint it with anything.