Rickresource Rickenbacker Forum

I am guessing that they oxidize to protect whatever they are coating and that the chalk is an oxide.

Good guess. Stains and pigmented stains are a lot different from house paints. House paints are emulsions (vinyl or alkyd), with vinyl being water-soluble and alkyd being solvent-soluble. They are made to sit on top of the surface they protect.

Stains generally are formulated to penetrate, although the oils in them can be self-skinning so they coat the wood, too.

Fender uses all sorts of different finish chemistries, from nitrocellulose (air-dry) to polyester (catalyzing) to conversion varnish. So we really need to be certain that we're comparing apples to apples when it comes to their paint finishes vs. CV.

PRS uses polyurethane CV. But they put it on very, very heavily. I have not heard about these not being as durable as a Rick finish, but the thicker the finish, the more susceptible it is to thermal shock...

Marine epoxies do not really chalk - at least not for long. They generally turn yellow and get rubbery (all the way through in the case of clear finishes) and crumble away - and this process of U.V. deterioration begins to happen in as little as 200 hours of exposure to sunlight (which ain't much for a boat). There is not a single marine epoxy resin made which is capable of being used as a stand-alone clearcoat for outdoor use.

There are three ways to prevent epoxy from failure do to U.V. deterioration. Overcoating it (paint) is the easiest. Another is to mix in an opaque pigment or an additive like graphite powder, aluminum powder or bronze powder. These act as a physical sunlight barrier which will stop deterioration near the surface, so that only the very top of the layer deteriorates and can eventually be either buffed off or sanded and renewed. On some colors, I suppose you could label this as "chalking" but it's really just a very thin layer of deteriorated resin/filler mixture. The other method of protecting epoxy (and the only way to protect a clear finish from losing both it's mechanical and cosmetic properties) is to overcoat it (and periodically re-coat it) with multiple coats of a varnish containing high amounts of U.V. absorbers. These can be one-part, spar-type varnishes or two-part, linear-polyurethane varnishes, which are harder and tougher, but quite hazardous to apply by spraying unless you happen to own a space-suit (cyanide).
If it's a boat and you see shiny (non-oiled) wood, you can bet your bippy it has multiple coats of varnish protecting it whether the wood is epoxy-coated or not. Epoxy alone will not work. This is my old 1960 Starboat. I veneered the sides with mahogany, stained them with alcohol-based stain, coated them with about six coats of epoxy resin, sanded it smooth and followed that with multiple coats of U.V. filtered varnish. As long as the varnish is maintained, it's a very stable construction. Without it, the sides would have been toast within a couple of years.

Thanks for the clarification - I'm leaning to using a solid color water-based stain this time...

Thanks, Todd. I was hoping you'd jump in, because of your experience with boat finishes.

BTW, at Concorso Italiano this weekend, there were FIVE Rivas--four restored 21-27 footers from the mid-'60s and a new AquaRiva 33'. I am nuts for the multiple-cockpit mahogany classics. The new AquaRiva is a stunning 'glass boat with mahogany trim and details.