: As Im painting the kayak I am currently building I was thinking of using some
: kind of easily sandable filler instead of just filling the cloth with
: ordinary epoxy.

You need two coats of epoxy over your wood to encapsulate it. I like at least two coats of resin over the glass-unless you can vacuum bag the thing and put on one thick, smooth layer.

After that, and a light sanding, if there are any indications that the weave of the cloth is still visible, why not use a thick paint for your first coat. This is the common procedure with canvas-covered canoes, and with canvas--covered decks on sailboats.

Rarely will you be able to find such a paint being sold. You'll probably have to mix your own. Fortunately (or unfortunately--depending on how you look at it) there are lots of "formulas" for mixing up a thick weave-filling base coat.

These resemble recipes for home-baked fruitcakes. Take a gallon of this, add a cup or two of that, and throw in a little bit of this or another thing. The recipes I remember tended to go with such cheap fillers as powdered chalk, or ground plaster, or ground up gypsum from reclaimed wall-board scrap. You don't want to use plaster of Paris, or wall plastering compound, which would become brittle and rock-like once it got wet.

White lead, a common and cheap pigment (I believe it is chemically lead oxide)which was used in white paint, and is frequently mentioned in old recipes for canvas-filling paints, was banned many years ago (except apparently in China). Don't bother looking for it.

Basically, you get a quantity of the paint you wish to use, pour off about half a pint, or 1/4 of a liter to use as your base coat, and add about the same amount of chalk or gypsum to this. Start with a small amount, and mix well. It will go on VERY thick, and should cover the weave in one coat. If this is too thick to handle, mix in a bit more of your paint to dilute the batch a little. Once this is dry, you can sand it. Chalk and gypsum sand very easily. You can sand this by hand. Once the surface is smooth, use the rest of your paint for the final coat or coats.

If your paint will bond to the epoxy substrate, then there should be no problem with using the same paint which has been thickened with these fillers. Years of use on canoes shows that these materials, when mixed with boat enamels are durable for a long time.

Hope this helps

PGJ