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-   -   Aluminum painting issues. (http://www.sailnet.com/forums/gear-maintenance/57621-aluminum-painting-issues.html)

SiXeVeN 08-31-2009 07:45 PM

Aluminum painting issues.
 
Ok, so I am painting some aluminum hardware. I know to acid etch and have zinc chromate primed the metal. The issue is that the zinc chromate is like teflon or something:mad: The chromate is bonded solid to the aluminum but unless I want baby poo green colored hardware, I can't get any topcoat to bond.

Any paint that I coat over the chromate barely sticks. I can peel it off with a fingernail! What is the secret? If I heavy sand the primer for more bite, I end up cutting through the primer. Can you use a traditional primer on top of the zinc chromate? Then use your top coat on top of that?

Help would be greatly appreciated.

I haven't tried a two part polyurethane paint yet...maybe that is the trick but I don't want to spend the big $$$ on the paint and have it still not stick.

roline 09-01-2009 06:11 AM

Perfection 2 part over a 404/414 Epoxy Primekote should last a lifetime when placed over an acid etched mast.
Now the issue is what was the zinc chromate paint base coat made from? enamel? Sounds like you may be forced to use an enamel topcoat to remain compatible. You need to find out what the zinc paint really was.

Flybyknight 09-01-2009 07:27 AM

I really question if it is in fact zinc chromate, because it's purpose is to facilitate a paint to stick like grim death.
A light green color suggests to me that it is in face a teflon primer, in which case nothing will stick.
Put a drop of water on it, and if it forms a bead, it's teflon. If it spreads out and wets the surface, then it is zinc chromate, which by the way has a brown color.
Hope this helps.
Dick

tommays 09-01-2009 07:48 AM

http://i565.photobucket.com/albums/s...collection.jpg

You only have 24 HOURS to overcoat

http://i565.photobucket.com/albums/s...g/750016_l.jpg
http://i565.photobucket.com/albums/s...ellowprime.jpg

With

http://i565.photobucket.com/albums/s...g/750091_l.jpg
http://i565.photobucket.com/albums/s...hiteprimer.jpg

If you not using one paint makes system your doing a cocktail and its diffcult to say were you went wrong other than its easy to go wrong :eek:

SiXeVeN 09-01-2009 04:14 PM

Quote:

I really question if it is in fact zinc chromate
Yes, that much I can be sure of. It is that rattle can stuff from West Marine that says ZINC CHROMATE in huge letters across the can. It bonds like superglue to the aluminum but I can't get paint to stick to it???

tommays,

I was looking at that interlux system. I was hoping to not have to go that direction as I only have a few small things to paint and I would have to pick up nearly 3 quarts of material between all three steps.

BTW, Are you able to brush on the Primewash?

tommays 09-01-2009 05:15 PM

Well

As i WAS NOT about to buy a can of black Perfection to paint a some cleats and both end-fittings of the boom i went the rattle can route

I just got them real CLEAN and used Rustolem primer and black paint and after one season in saltwater they look fine NOT as fine as the Perfection but fine enough ;)

US27inKS 09-01-2009 05:47 PM

Quote:

Originally Posted by SiXeVeN (Post 518962)
Yes, that much I can be sure of. It is that rattle can stuff from West Marine that says ZINC CHROMATE in huge letters across the can. It bonds like superglue to the aluminum but I can't get paint to stick to it???

tommays,

I was looking at that interlux system. I was hoping to not have to go that direction as I only have a few small things to paint and I would have to pick up nearly 3 quarts of material between all three steps.

BTW, Are you able to brush on the Primewash?

When I painted my mast and boom, I went with the interlux products and followed the directions to a T. I also sprayed mine. They came out perfect, but brushing may not look as good.

I had a few small items that needed to be refinished. I took them to a powder coat shop. They look great and have a very tough finish.

Northeaster 09-01-2009 07:23 PM

If I were coating something important, like the mast, I would use quality products, and follow instructions, to a tee as well.

However, 2 season ago, I needed to redo my 30 year old Bomar Hatch frames (before putting new acrylic in them) and rebedding.
I cleaned all paint off with a wire wheel, then cleaned with vinigar, and sprayed them with a primer (made for aluminum, from an auto parts store).
As I wanted them black, and didn't mind a bit of texture, I sprayed them with a can of truck bedliner / auto rockpanel rubberized paint.

Time will tell, but it's been two seaons, and thye still look perfect.

I think one has to consider the project, and it's impact on the total boat.

I would put more effort and $$ into redoing hatches on a classic, 1/2 million $ yacht, than I would on my 30 year old 30'er. The rest of the boat is in decent shape, but by no means pristine. To spend mega $$ and time, on finish, would not make sense to me.


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