Yes it is the high solids of the paint that makes it heavy. In most cases when paint dries the solvent evaporates leaving only the solid pigment behind. You add a solvent to the dries paint, it becomes liquid again.

Much like plastic airplane glue, the acetone evaporates and the glue becomes solid. Mix a little acetone to the glue and it become sticky glue again. Unlike epoxy, or eurathane which must have a catalyst which bonds the molecules together in a chemical reaction.

POR-15 cures by the exposure to moisture, not by evaporation of any solvent.

Sanding some of the mass will reduce weight, but not really enough to make a difference. When you sand, you are really just sanding off the bumps and getting the surfave of the paint level (smooth). A smooth level surface is what makes the paint glossy.

When ever you brush paint, you will leave brush streaks, thus the surface is very rough. With a product like POR-15, the paint goes on so thick and cures so slow, that it flows out to become smooth and glossy, only by the build up of the paint and the leveling effect of the slow cure. That is where the weight comes from. When you sand it, you are only sanding off the bumps and imperfections. Then you have to buff it to remove the micro scratches left by the sand paper.

You really won't sand off much material, therefore you will have a heavy paint job. By spraying paint on, you get a more uniform thickness and glossier surface that requires less sanding.


Frank