Paint on Aluminum Bracket

I have an engine mounting bracket with some small chips starting to flake off. Paint has seperated or bubbled away from the aluminum in a small area. I can see, in another area, where in the past this happened & was painted over. Has anybody out there had any luck "touching up" areas like this? What should I use? Thanks in advance, AL

Re: Paint on Aluminum Bracket

Hi algee. You need to feather the bad paint off with sandpaper. Get the big pieces off with a scrapper, then sand down the rest until you can't feel any ridges where the metal is exposed. Prime with zinc oxide and then paint.

Re: Paint on Aluminum Bracket

Mine was doing the same thing. I had pulled it off to paint the boat and give the boat a new engine and so I figgured it was time to do something about it. Mine had been flaking for a year or two. Its a bracket by Gil and the paint that was used on it was probably a 2-part epoxy, very thick.<br /><br />I had the bracket sand blasted and then immediately painted it with zinc chromate primer. It is my understanding that you must prime aluminum within about 4 hours of either sanding or blasting or aluminum oxide begins (obviously it begins immediately but 4 hours is OK from what I've read) to form and once that's happened no succeeding coats will hold.<br /><br />Anyway I had it sand blasted and primed it. I then followed that green zinc chromate with two coats of Awl Grip 545 white primer and that's where it stands right now. I haven't gone any farther with it because I don't know what color I want it to be. I could just use the same paint that is going on the hull (an off white Awl Grip) or I might paint it back to close to its original medium gray color, or maybe I'll paint it to match the deep charcoal gray of the new engine. Just not sure. For finish coats if I decide to match the hull I'll just use the same paint for it (Awl Grip) but if I go with some other color I'll probably just take it to an auto body shop and have them shoot it in Imron.<br /><br />Thom

Re: Paint on Aluminum Bracket

Algee - After cleaning off the old stuff, you should prime the bare aluminum with zinc chromate primer. As far as we are concerned, the only difference between the yellow and the green is color. (Technically, the yellow primer is less resistive to electrical current, but to a degree that doesn’t matter to much of anything.) Often a ‘normal’ primer is applied to the zinc chromate, but it is not necessary. Thom’s 2 coats of white primer will hide the ‘green’ and allow him to paint the final coat any color he wants.<br /><br />In a spray can, zinc chromate goes for as much as $16 at marinas. The exact same primer (Tempo brand/12-oz can) is available from aircraft supply places for as little as $3.50/can. Also available online. I have only seen one other brand, same primer but costs even more.<br /><br />Zinc chromate is high on someone’s “we’re scared of this stuff” list and was removed from a lot of primers. It is still the best sacrificial primer for aluminum parts and as such it is still used in the aircraft and marine industries.

Re: Paint on Aluminum Bracket

My friend just had his bracket powder painted (it was off of a 1987 Grady White Offshore 24), just before he put a 225 Yammy 4-stoke on it.<br /><br />It looks great, and should hold up a long time.<br /><br />He took it to a car shop that powder paints car frames.

Re: Paint on Aluminum Bracket

Thanks All, Zinc Chromate primer It is. I hope I can do a small area, do not want to remove the engine.