Prepare the Hull

• Completely strip and clean all aluminum surfaces intended for paint, using a commercial-grade chemical stripper if needed. It is easiest to do this work on shore in an area protected by sun, rain and pesky bugs. If a hull has already been painted, a simple scraper will remove most of the old paint.
  
  

Etch and Prime

• Because aluminum is a light metal that resists painting, the hull will need to be etched so the paint particles will have irregular surfaces to cling to. Although there are chemicals that do some etching and some priming simultaneously, the etching and priming are more commonly done as two steps. Ensure adequate ventilation and safety gear, as most etching compounds are highly acidic. For maximum paint adhesion, the outer layer of aluminum oxide must be removed from the base metal before painting, yet doing this properly requires commercial-grade chemicals or time-intensive sandblasting. Both of these approaches can be a challenge for a backyard hobbyist, so you might consider using very fine sandpapers because they can also get the job done.
  
  

Paint

• Apply the paint. To a properly prepared hull, most paints will work, including automotive spray paint or brush-applied marine paints. Ensure adequate ventilation, and apply the paint according to manufacturer instructions. If you are using a non-marine paint, read the label carefully to assess the paint's toxicity in the water.
  
  

Is Painting Needed?

• For typical aluminum-hulled fishing boats and canoes, paint is not necessary to protect against damage or corrosion, so the purpose of the paint is purely cosmetic. Because of the difficulty of cutting through the aluminum oxide, consider whether another option might meet your needs.