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Ted Mooney, P.E. RET
Pine Beach, NJ
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for Metal Finishing since 1989
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Repairing Rusted Area on Galvanized Boat Trailer
Q. I have a Galvanized Boat trailer that has some rust spots from use in saltwater. Most of the rust is surface type on support brackets that are welded to the frame. I do not want to paint over the rusted areas. A few questions pertaining to Galvanized problems:
B. After sanding the surface rust off in some spots, what should I use to prevent rust again?
C. Is there a product or procedure that I can use to obtain the galvanized protection again over the clean rusted area's from the Saltwater?
DAVID STOKES
- Wellsville, Pennsylvania
2003
A. Galvanized materials are steel that was dipped into molten zinc; the zinc sacrificially corrodes to protect the steel. Corrosion of a galvanized material proceeds in two stages: first the zinc corrodes, leaving white corrosion products, "white rust", often erroneously believed to be salt stains; then the steel corrodes, leaving the familiar reddish-brown "red rust".
Once you see powdery red rust, there is no more zinc in that area (although a rust-colored general discoloration doesn't necessarily mean all the zinc is gone). The best repair is probably a zinc-rich paint, sometimes called 'spray zinc' or 'cold galvanizing compound Cold Galvanizing Compound / Zinc Rich Paint.
Although no paint or other repair will equal the original galvanizing, and you won't be able to get it inside the tubing as was done originally, it may be reasonably good at corrosion resistance as well as aesthetically passable.
I would go easy on the "sanding" idea since you don't want to remove any zinc. A wire brush will probably be better than sanding. Then use a rust converter
⇦ this on
eBay
or
Amazon [affil links]
on any actual rusted areas, then spray those spots/areas with the cold galvanizing compound. The original galvanizing can have a mottled look anyway, and everyone is used to seeing these sprayed zinc paint repairs, so the 'spot repair' methods may look alright, but you can spray the whole trailer with the cold galvanizing spray if you prefer. Good luck!
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. I saw a can of cold galvanizing recently. It is a zinc rich paint that looks more like silver than galvanize. Do not expect much from it on a salt water boat trailer.
James Watts- Navarre, Florida
I think I'm going to rub as much rust off I can, and apply a product called Por-15 Rust Protectant
⇦ this on
eBay or
Amazon [affil links]
and paint a Glaze Gray over the POR-15. This may resolve the rust appearance on the boat trailer. Thanks again for the help.
- Wellsville, Pennsylvania
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Q. I am currently restoring a galvanized boat trailer. I have several questions mostly to do with safety. The surface of the trailer varies from good (galvanized layer still intact) to completely rusty. hobbyist - Chester, Vermont, USA 2006 A. Hi Scott. It is not so much a question of zinc being bad for your lungs, or steel being bad for them, or rust being bad for them; rather, you don't want particles of anything in your lungs. So a particle mask is what you want for sanding or blasting, a chemical mask to neutralize acids is what you want if you are acid washing, and a charcoal mask ⇦[this on
eBay or
Amazon affil links]
is what you want for painting or stripping or anything involving organic vapors Q. I have a painted boat trailer and am looking for advice for the right coating that would prevent rust and seal the metal. I am having it media blasted. - Corpus Christi, Texas 2007 Q. I have a Galvanized boat trailer and I was wondering if it would be ok to give the trailer an Acid bath like you would on old Aluminum to make it look like new again Denis Kenshalo- Merced, California, USA August 31, 2007 A. Scott, we have many threads here about welding galvanized steel. If you inhale the fumes you are likely to get 'metal fume fever' (try searching the site with that search term for more info). So make sure you have very good ventilation, and preferably it should be done by a pro with a self-contained air helmet. I don't see any danger in sanding or blasting, but wear a respirator or at least a painter's mask when sanding anything -- you're not supposed to fill your lungs with particulates no matter what material they are. I think you are best served by leaving as much galvanizing in place as practical. I think the 'cold galvanizing spray' is a pretty good finish (see my response above to David if interested). Mike, epoxy paint is fine if the metal is pretreated, but I think a zinc rich paint is best for a trailer because the zinc sacrificially corrodes, protecting the steel. Denis, the acid bath would immediately and completely remove the galvanization, leaving you with plain steel highly prone to rusting. Sorry, but galvanization is not a decorative finish. If you don't like the look of your old trailer, give it a wash like it was a car, then prime it with Self-etching primer ⇦ this on eBay or Amazon [affil links] designed for galvanized finishes, then do a top coat of whatever you like. Good luck! Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey A. Go for a Zinc Rich Primer - if properly prepared, these can provide protection as good as Galv. You can put a barrier coat over the whole lot as well if you want - this will extend the life of the system. Simon Williams- London, UK March 11, 2009 |
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Q. Hi Folks. I have a custom boat trailer that is rusting. Anyone with tips and product suggestions please chime in.
Kevin Mc grathconsumer - Redway, California USA
March 30, 2009
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Q. Hi there, - Singapore September 20, 2012 A. Hi, Senthil. Zinc-rich paint does not offer the protection of hot dip galvanizing. Because the work is already done though, as a practical matter it's probably a good idea to offer the client the painted roof structure at a discount :-)
Regards, Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey |
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