: I am considering using elastomeric roof coating to waterproof/finish the
: canvas skin on the sof we are building. Does anyone have any experience
: with this product on canvas? Any reason why it would not be a good choice?
: Thanks.

Greg,

There seem to be several brands of elastomeric roofing products, and some of the product lines have materials with two different viscosities. I guess I could call one version "thick" and the other "thin". The "thicker" material may be promoted as a roof patching material. It goes on thicker, and might need to be thinned with more water if used for a first coat. The "thinner" material might be sold as a roof covering material. It is very similar in viscosity to latex interior wall paint, and needs just a bit of thinning. You would put on an extra coat or two if you use the thinner material. Other than that, either the thicker or the thinner stuff should work fine.

The instructions say to apply this on a warm day with lots of sun. I put mine on in a basement with no sun, and it seems to be OK.

These roof coating materials have no mold preventing capability. You might want to find a mold inhibitor or fungicide at the paint store and mix some in. Otherwise, soak the canvas with a mixture of borax (BORAXO) in hot water, before covering with the elastomeric coating. Hopefully this will help to keep the canvas from rotting away in a few years.

Otherwise, get the interior dry as soon as possible after each use, and keep it dry,to prevent rotting of the canvas.

PGJ