The process for painting aluminum is a total pain in the behind. If you do it right the paint will last a long time. However if you don't the paint will peel off in no time at all. ALuminum has a natural oxide coating on it's surface that protects it from corrosion. That's why you see so many aluminum boats that aren't painted, and why aluminum fuel tanks aren't painted. However, to paint it you have to remove the oxide which requires essentially etching the surface, cleaning, coating with a base coat and then painting. Here's something on the subject because I have been asked this question thousands of times about aluminum fuel tanks. New Boatbuilders Home Page - Hot Topics for boatbuilders
There are some good links on that page. After the links it's all about fuel tanks so unless you're interested you can skip it. Frankly I would follow the advice above and have it anodized. Anodizing will last almost forever.
04-02-2008 02:07 PM
If you decide to paint it, strip it, acid etch it, alodine it and use a zinc chromate or epoxy primer then finish with Alumigrip or something similar. This is the standard process for refinishing aircraft and the paint typically last for 10 years.
04-02-2008 01:54 PM
Take it down to a local metal plating company and have them anodize it. (Hard anodizing is generally more durable and thicker). Will give a nice durable coating, you can generally get it done in clear or black for a base price and for up charge get a custom color. Will last longer than paint or powder coat and won't corrode like bare aluminum. If you are handy and like to play chemist you can do it yourself in the garage. The directions on the following link DIY Garage Anodizing are what some students in a course I taught a few years ago did. The results were as good as what they could get from a local shop (note that this is regular, not hard anodizing).
In my opinion aluminum should always be either coated or anodized, never left bare.
04-02-2008 01:25 PM
leave it bare and make a cover, with a draw string or elastic, out of Sunbrella material. simple
04-02-2008 12:06 PM
Aluminum: To paint or not to paint
I have my windlass removed for another project and it is dissassembled for seal and bearing replacement. When I was in the yard they were testing a new method of blasting. I offered the casing up for a trial. The orginal paint was really ready to come off.
The question is---
Spend the time to paint it with an LP (Time consuming)
Have it powder coated (Will cost some money)
Leave it bare aluminum (Easiest)
Do I run any risks by leaving it bare for an extended period?