I go nuts every year repainting my darn floats. Last year I used some lead based fuel tank sealant as paint on teh bottoms of my floats. It sorta worked. At least i had less fouling. Since I operate out of a semi-salty lake with all sorts of yucky stuff in the water, I have a real problem with corrosion happening under the paint. Even though I strip, acid etch and alodine the aluminum before painting.
The best all around stuff is the following:
RANDOLPH SPECIAL PRODUCTS
Float lacquer is a time-honored silver coating for aircraft floats. Although it can be applied by brush, it is more suitable for spraying. Float lacquer is a classic, low-tech way of coating floats. Although its service life is far less than today’s polyurethanes, its ease of application and repair make it a useful product. Apply over epoxy-primed metal or directly over old float lacquer.
Packaging: Quarts, gallons, five gallon pails, 55 gallon drums.
Shelf life: One year in unopened containers.
Coverage: 225 square feet per gallon.
Mixing: Stir thoroughly before use. Insure all the silver is in suspension.
Thinning: Thin one to one with 286 Nitrate Thinner.
Stripped or bare aluminum: Use phosphoric acid etch and conversion coating. (See acids in the Ceconite Procedure Manual 101.) Prime with epoxy primer. When dry, scuff with an ultra-fine scotchbrite pad. Clean well, then spray three coats of 1:1 thinned float lacquer.
Old float lacquer: Clean well, scuff with an ultra-fine scotchbrite pad and spray float lacquer as required for cosmetics. Can be brushed, although spraying results in a better coating.