I think some do this to be able to see where the current coat of expoxy has been applied and how well it has been applied.

   To get a smooth, drip and run free surface using epoxy you would have to block sand until it was flat and then polish it with a buffer and rubbing compound. At least you would if you wanted a shiny finish. If you just wanted a flat colored finish you could stop at whatever grade of sandpaper made you happy.

Gerry,

Epoxy is wonderful stuff, but it has at least one major vulnerability.  UV light from the sun decomposes it --- breaks it down so that it turns chalky, loses it's strength, and rubs off.  Marine paints and varnishes are formulated to block UV light and are necessary to protect the epoxy from UV light's harmful effects.

Regards

   https://www.dropbox.com/sh/l7g3scc0h61m6ts/2pNuj3GIz1

I used a pigment with West epoxy for the hull of this stand-up bpard.  I coated it with mutiple coats of varnish. IMO The color is better and less likely than paint to show a bad scratch.

I did however have my first experience with BLUSH once I pigmented the resin. If you pigment let it dray an extra day and then do the soap scrud to ensure all the blush is gone  - varnish does not dry over blush.

   And type more carefully than me!!