Originally Posted by Boatguy30
I was wondering if you used some kind of acid etch type stuff. I have done very little painting of aluminum
, but my mast does look like crap. I'm hoping a nicker looking one comes along before the boat is done!
Getting ANY paint
to stick to aluminum is a challenge, but it can be done. I suggest you use the prep instructions in the AwlGrip "blue book", as they are the same (= best) instructions no matter what paint
It involves first... stripping the mast, then multiple solvent &/or water
and "stripper" Scotchbrite wet scuffs under full water
flow. These are followed by Alumaprep and Alodyne etch & pre-prime steps. Then DO NOT TOUCH IT with an ungloved hand, but start priming as soon as it is dry. Done properly, with 3 topcoats over the primer, it will stick great and last 25 or 30 years!
LP PAINT SYSTEMS ARE NOT FOR EVERYONE:
It is all about the proper prep and execution... Without taking each step according to the manufacturers' instructions, (just like a skilled chemist), a 2 part paint system will definitely fail, and being solvent proof, it will be much harder to re-paint over. Quick n dirty painting should not be attempted with 2 part paint systems, imo...
YOUR PRIMER QUESTION:
AwlGrip's primer is 2 part 545 epoxy, and Sterling's is a 2 part polyurethane
. IF your primer goes on smooth enough, you CAN topcoat the next day with the LP topcoat, and get an EXCELLENT chemical bond. It will just have a rougher texture from the unsanded primer's stipple. Otherwise, it must be sanded with 280 or 320 grit EVERYWHERE, or at least take a Scotchbrite to those difficult areas to sand.
BEAR IN MIND:
On ALL 2 part systems, the very solvent resistance we love, means that after the 24 hour chemical bond window is over, the topcoats will get NO bond to the primer, unless the primer is scuffed to a TOTAL glaze, over 100% of it's surface! Try to sand/scuff it VERY thoroughly, without going through.
On all of my nonskid decks, and a lot of deck's edge radii, I went for the chemical bond, and I didn't sand the primer at all. I painted in sections, and got the topcoat on the very next day after priming. This cuts the labor of painting in half!
Under my wings last Summer, I combined both concepts... I rolled on 3 coats of primer on day one, and on day 2, I sanded under there VERY lightly to knock down the stipple, (in 1 hour). Then I wiped and tacked. This was immediately followed by the first of 3 LP topcoats. This in turn was followed on subsequent days, by top coats #2 and #3... Each coat went on within 24 hours of the one under it. In my case here, A light/fast primer sanding
was fine, WITHIN 24 HOURS OF PRIMING ONLY. Otherwise...
Same is true of any 2 part topcoats. You can spray on all 3 of them in ONE day, the day after priming, OR if you're roller/tipping as I was, get the topcoats on 1 coat per day, but on subsequent days... (Without sanding)!
These bonding tips are the only types of "short cuts" that will definitely work, btw. Break the systems rules otherwise, at your own expense!
More than any other part of the boat, a really good 2 pt paint job on the spars will pay dividends later. A mast can only be re-painted by removing it and most of it's hardware
first. It is easier to avoid it for 25 years.
Also... On ALL SS hardware
mounted over these newly painted spars, use a thin Teflon or equivalent sheet under winches (with their bronze bases), AND caulk down everything else. The combining of dissimilar metals on the Aluminum becomes much more problematic, IF sea water can get in the interface between them. Caulk solves this to a degree. Still, after decades at sea, around the bases of SS hardware is where the paint will start failing first.
Aluminum on Aluminum is less of a paint failure problem, but still, caulk ALL hardware bases AND fasteners well. The best SS machine screws I have found, btw, (for avoiding corrosion), were actually dipped in molten Aluminum, but I don't know if they are still available. I got mine as part of a Lifiel kit, (sp?) 30 years ago.
Good luck with it...
In the photo
below of the ceiling of my wing's vent hole, all of the priming and 3 topcoats, were done with a brush, even between the legs of the epoxy bonded in lashing eyes. Spraying looks best of coarse, roller tipping CAN be a close second, and where it never shows, (like under here), any way of getting it on will last just as long. Under here out of the sun, it should never need paint again.