Posted by Eric S on May 16, 2004 at 15:28:37:
In Reply to: Re: Painting Scuba Tank posted by Dave on May 16, 2004 at 08:18:37:
Ok,
Here's what you do.
First, if you want a very smooth paint job, it may be necessary to sand the surface with a sander with 180 grit automotive sandpaper(use a d/a sander, the type they use in body shops) then give it a coat of self etching primer. There are several types but the one that comes to mind is DuPont 615s veriprime. It is an acid base that requires a converter that you mix with it. DuPont also makes a spray can version that is cheaper to buy but I don't think it has quite the bite that 615 has. Only one coat of etch primer is necessary.
Next, if the surface is pitted or has texture you may want to spray on a catalyzed primer surfacer. This will fill any surface texture that the galvanization might have. If you do choose to use a fill primer, spray on 3 coats and then dust on a guide coat of cheap rattle can primer of a contrasting color that is sandable. It should have a specked look when you are done. This so when you finish sand the fill primer, you can have a visual aid to see how your sanding is coming along so you don't miss any spots.
Next, buy an industrial catalyzed urethane such as DuPont Imron 333 which comes in many colors. Or you can also use an epoxy mastic such as DuPont Corlar 25p which also comes in a variety of colors. Corlar 25p also requires a catalyst. Both are very tough and are what they use on steel work boats. If you want a glamour metallic then you will have to get a base color coat and a urethane clear coat. This would be what 99.9 % of the vehicles on the road have on them, but it is not going to be as durable as the industrial stuff.
Spray the product on as directed. The Imron 333 you spray all at once, a tack coat then come back and cross coat till it wets out. The corlar is some gnarly stuff to spray but you can put on up to 12 mils. The corlar will dull out slightly to a satin sheen but gets so hard it's almost like enameled steel.
All this stuff is spendy and you have to get it at an automotive paint supply store.
I forgot to add, tape off the valve and hang the tank to work on it. Don't put the boot on till the paint is fully cured.
Or, just pay a pro and save some time and money.
Hope that helps.