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View Full Version : Rust Removal and Re conditioning surface rust spotted Boat Trailer



PeterInSA
23-12-2011, 02:01 PM
Am a great believer in Rust converter and Zinc/Cold Gal.
However have read that you should not use Spray on Zinc/Cold Gal if using rust converter.

I first go over with a wire brush to get rid of surface rust, than rust convert then........... spray on Zinc/coldgal paint on.

Am wondering if any residue of the rust converter reacts with the Zinc/Cold Gal etc.

Comments appreciated

Peter.

Fed
23-12-2011, 05:05 PM
I'd clean it up and paint it with brush on Cold Gal.
The only downside it that it's damned expensive, I paid $90 for a Litre about 10 years ago.

whiteman
23-12-2011, 05:15 PM
Add some Penetrol to the gal (around 25-50%) and you might have a chance of holding back the rust as it will provide a much better seal. Cold gal alone has NEVER worked on my trailer. Rust converter shouldn't be an issue but I'm sure there will be a chemist lurking to give a better opinion.

deckie
23-12-2011, 06:16 PM
I've also heard u shouldnt use rust converter under other coats of just about everything..not just the cold gal, everything. But never stopped me. There's probably a good chemical reason not to, but in practice most ignore it i guess.
Check as well if cold gal only works via contact with existing gal, pretty sure thats the case. Many seem to think its like a rust prevention paint over steel. Not cheap and i reckon its overrated unless used as intended.
I;m another who has gone down the marine penetrol route recently when redoing an old trailer that was in good nick. Have seen the results so went with it, 2 coats as a primer ..stuff is ultra thin and seems to soak in..to me a ohysical barrier is as good as any. Its not a new product but hoping the old guy is right...no downside so giving it a try but too early to vouch for it. Overpainted that trailer with por15 chassis/block paint..make sure whatever the surface coat is that its UV tolerant coz many arnt.
Still a huge fan of GOOD fishoil not the cheap shit about. Used tectyl for axles/springs

cormorant
23-12-2011, 09:05 PM
POR product is good if the preparation is good and no UV is on the finish or it has to be topcoated.

Wire brush get rid of scale but unless fresh and very tough don't really prepare a surface for painting. Sand and the area afterwards so the paint gets some bite on the metal.

deckie
23-12-2011, 09:15 PM
por15 make a UV called "sterling silver", wanted to try it (no idea why but i just decided to do it) and found this was their only UV stable one. Yeah most need a topcoat. There are a few of these about and might be all owned by same crowd. Can go straight over rust apparantly but this one was a 25yo trailer that was almost pristine condition to start. Like i said tho cormorant...too early to tell yet, and i cant resist still whacking fishoil over the top on the back half as well. Time will tell...the trailer was still so damn good after 25yrs its worth a plug for Tracer trailers who are still a popular builder here in Syd. Are there good gal jobs and lousy gal jobs ?

cormorant
23-12-2011, 09:35 PM
Didn't know that they had a UV topcoat. Had used their stuff on pumps in sheds and it worked well. There must be another product as well as I have seen it used direct and last years on wharf railings. maybe that is teh silver one.

Yeah the problem with rust is that it holds moisture as it is porus. We hit spots with gas burner to ensure it is dry and scale as much off as possible.

Worst rust problems are when people try and cover em up rather than prepare and fix it properly.

Dave666
24-12-2011, 04:30 PM
I had a friend do the following application. I was thinking of doing the same and would be interested in opinions.

Welded shut all subsections and put fishoil inside. Wire brushed external, gold gal paint, kill rust primer, followed by two coates of epoxy paint. Then he tectyl everything except the front 1/3 of trailer.

Sounds like a lot of work - is it worth it - what do you think?

Dave

oldboot
24-12-2011, 09:21 PM
I've had some bad results with rust converter, because it is mostly acid, if the reaction is incomplete it may in fact promote corrosion.
If there is too much rust for complete conversion, active rust can remain, again more corrosion.

I have had very good results by using a flap disk on a grinder to remove the bulk of any rust or degraded gal.
Then using an oxy torch to heat any remaining.....the rust dries out and sometimes pops off like little fire crackers, and the degraded zink likewsie decomposes.
Follow that with a wire brush on a grinder and you will get a far better result than rust converter.

I prefeer to brush on a thin coat of an etching undercoat like wattyl super etch then go either cold gal and or galmet duragal.....I tend to hit the bare metal parts with the cold gal and do a complete coverage with the duragal

Had very good long term results results with the above.

But you have to get a decent cold gal..some of the cheaper ones have neither the amount of zinc nor the quality resin.......I like the galmet cold gal, but others i know like Galvit E90.

A good cold gal is like a zinc slurry made on resin..very heavy in the tin, and alittle goes a long way.

I've seen cheap cold gal only last a couple of months.

cheers