: Despite the fact that most of the people on this board claim to know more
: than the manufacturer of products (epoxy and varnish), I trust the
: manufacturers more.

: The usual instructions are to thin as little as possible except where trying
: to penetrate wood surfaces. This is because there is a balance between the
: reactive hardeners and the evaporative thinners in varnish. The hardeners
: must evaporate before the varnish hardens or else the varnish is soft and
: porous.

: Your first coats appeared to not need thinners - must have been a new can of
: varnish. The last coat needed thinners to make it flow because some of the
: hardeners had reacted and some of the thinners had evaporated. You should
: have used fresh varnish for your last coat.

: For spraying you want to add just enough thinner to compensate for
: evaporation during the spraying.

Has anyone kept track of how much weight each coat of varnish adds to a typical 17 ft kayak or canoe.I would imagine that most of the product in the can evaporates away and that the solids that are left on the boat are not that heavy,maybe a couple of ounces per coat.