Boat trailers

Hi Jon.
Dont know were you are from, but Paint Supplies, in Adelaide has special paint that can be used in marine applications, that somehow will convert/nuetrilise the rust, and leave a good protective coating again. Cold galv, applied thickly over non rusted steel works well, but nothing like hot-dipped steel.
Trev

If its a box section chassis the rust may well be coming from within.

Whilst the trailer may have been washed down externally how many times have you flushed the inside of the rails etc

As has been said if the rust is coming through a box section from the inside maybe time to look for a new trailer.
If however it is just surface rust on the outside there are a number of "rust converter" products on the market. The one I have used with a good degree of success is called Fertan.
You remove any loose or flaking paint and rust but don't remove all the surface rust. This stuff needs some rust to convert to a stable black coloured finish. After giving it a few hours to set you then apply water and let it dry thoroughly. Not sure just what that step is all about but it seems to work when done. You can then re-coat with cold galvanising paint.
The main point to remember is to not remove all the rust. Just the loose flaking stuff.

Cheers
Pop

I used Valvoline Tectyl on my boat trailer, it is a sticky browning product that comes either in liquid or aerosol. Just spray on and it adheres well to rust. Others swear by Lanotec, similar treatment. The trailer frame is made with holes in it to facilitate the galvanising process. You must hose inside all open framework with fresh water every time you use the trailer, then leave it tilted a bit so any water can drain. The fussier you are the longer the trailer will last.

We build crash rails for the RTA..
and all rails are galvanised to a RTA standard.
any chips or repairs require
a JOTUN zinc rich primer which comes in heaps of sizes..
a l ltr pot weights like 2.5kg or soo
and a duragal two pac top coat
sometimes we just use gal sticks and duragal silver on the last coat.

if the surface is going white..
that means the zinc is reacting
doesnt mean rust but good idea to keep an eye on it and either coat with some decent paint.

if its surface rust just mild brush and scale it off
jotun is used by the trade in all gal jobs...requiring to meet the required codes
the stuff is that good
cheers

Bolt on a sacrificial zinc anode.

Cheers,
Peter
OKA196 motorhome

Happytravelers - Acquire a litre of Phoenix Metalfix paint. It's a water-based rust-converting paint, invented and made in W.A., that is as dear as sin - but once you paint it on, nothing will ever affect the area again.

It withstands 1000 degrees of heat, salt water, acids, and anything that causes corrosion.
You can paint over the top of it with any other paint once it's dried.
It dries within about half an hour in warm weather and a couple of hours in cold weather.

The rust needs no preparation, other than just wire brushing the loose scaley rust off, pressure-washing the area down with clean water, letting it dry, and paint the Metalfix on.

Metalfix can be thinned with water (but not more than 2 to 3 percent) if it has dried out somewhat in storage - and it lasts for years and years in a sealed container.
I have some in used containers that is around 20 yrs old, and it's still good to use.

Your trailer sounds like it was badly prepped prior to galvanising. Proper prepping with a thorough acid bath is vital for good galvanising results.
It's no different to painting really, if you don't do the proper prep work, look forward to seeing your paint or galvanising fall off.

Cheers, Ron.

Re Rust Converters and Overcoating with Cold Gal.

Please read the write up on the Rust Converter Container. If I use the Rust Guard ( Converter) that I have, The Overcoating Para. states that an Epoxy enamel or other metal finish paint should be used.

It goes on further to state: Do NOT overcoat with Cod Gal or Zinc Rich products.

Peter