Re: Powder
Local Motion said:
On the boats, when the finish on anodized aluminum is done, it is done.
I had a motorcycle frame powdercoated when I was building one around 5 years ago.
Powdercoat is tougher than paint.
Powdercoat is very thick and will help hide SMALL blems.
The problem with powdercoat is if it gets chipped....you can't fix it because spraying it and cooking it in the oven is a one shot deal. The chipping can spread and look real bad. On a boat, things can bang into the aluminum and chip it, so I don't know if I would do it on a boat. On the other side of the equation....having done it do a motorcycle and riding 70 miles an hour, I saw no chipping from road debris and while I was building the bike occasionally a wrench would slip and I would bang the frame. It did not chip. Powdercoat is tough stuff. I would expect, as with other things, how well the shop people do the prep work will determine the outcome of the job for the long term.
The windshield frame on my boat, I use topsides black paint. The powerwasher knocks some off each year and I just touch it up every spring. Easy enough for a windshield frame.
I'm impressed. I'm an old painter from waaaay back as well. Since the '70's in fact. About powder coating, that is absolutely true, and when I was doing vintage restorations on bikes I did not use powder coating for this reason. With paint you can always sand it down and re-shoot it. Particularly for dirt bikes, the front down-tube always gets sandblasted from dirt and rocks. Paint is easy to restore, powder coating is virtually impossible. Some guys didn't care, they could drop the frame off to a coater, they would sand blast it and coat it for a very reasonable price. I used to be able to get a frame blasted for like $60. Then start building up coats of primers, etching sealer first, then primer, sealer, and a topcoat of acrylic enamel with a hardner/cross-linker.
As far as types of paint, Imron is a 2-part polurethane that was developed for aircraft. It's like liquid plastic. It does work very well and would be a good choice, however it is VERY expensive. The aluminum would have to be sanded or blasted and the proper primers applied. The downside to imron for autos and boat finishes is that you can't wet-sand and polish it, again, because it's like plastic. Another dupont product we liked was Centari acrylic enamel. With a cross-linker additive it hardens up like urethane, and can be wet sanded and polished the day after shooting.
None of these products are available in CA anymore due to CARB (california air resources board, i.e. the bastards) but may still be around in other states. I'm going to try and buy some Centari in AZ when I'm over there during the holidays.
For aluminum top tubes I would lean toward an epoxy paint. Imron would be a good choice, or any 2-part epoxy based paint. I'm not a big fan of powder coating, but it is an option. Any chips or nicks will allow corrosion to set in and the area will fester and boil, eventually chipping the paint off.
Let us know what you choose and how it works out.