Home /
Search 🔍
the Site
pub Where the world gathers for
plating, anodizing, & finishing Q&As since 1989


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:

A. How can I clean galvanize for a better Trailer appearance?
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?

- Wellsville, Pennsylvania

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 / 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 [affil link] 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, finishing.com
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

thumbs up signI think I'm going to rub as much rust off I can, and apply a product called POR-15 [affil link] and paint a Glaze Gray over the POR-15. This may resolve the rust appearance on the boat trailer. Thanks again for the help.

DAVID STOKES [returning]
- Wellsville, Pennsylvania

similarly -- these entries appended to this thread by editor in lieu of spawning duplicative threads

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.

Are there any hazards involved with sanding, grinding or sandblasting a galvanized trailer? Will a particle respirator be good enough protection? If the surface is completely rusty is it safe to assume that any zinc from galvanizing has flaked off long ago. Also if you were to grind off the galvanized layer is it safe to weld these areas as you would any mild steel?

I am only planning on removing the rust etc. from the bad areas and leaving the parts with the good galvanized alone, what would be the best way to prime and paint steel that is only partially galvanized?

Thanks in advance for the help.

Scott Jackson
hobbyist - Chester, Vermont, USA

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.

I have been referred to an epoxy paint and also a zinc paint.

Any help would be appreciated.

Mike Newhouse
- Corpus Christi, Texas

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

Cold Galvanizing Spray

Affil. Link
Your purchases make finishing.com possible

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 [affil link] designed for galvanized finishes, then do a top coat of whatever you like. Good luck!

Ted Mooney, finishing.com
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

-- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi Folks. I have a custom boat trailer that is rusting. Anyone with tips and product suggestions please chime in.

Kevin Mc grath
consumer - Redway, California USA
March 30, 2009


Q. Hi there,
Currently, my company is doing this steel roof structure at seashore jetty house project and client wants us to hot dip galvanize the steel structure.

The steel structure is already fabricated and uses galvanized paint.

Should I go for hot-dip process or galvanized paint is enough?

- 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 :-)


Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

Chemicals &
Consult'g, Train'g
& Software

About/Contact    -    Privacy Policy    -    ©1995-2023 finishing.com, Pine Beach, New Jersey, USA