I've used Black Knight Clear (water based )roof coating brush grade on synthetic skin both nylon and polyester from Dyson. It may work on canvas . I will test it on a piece of 15 oz canvas and report back to you in a day or two . You can get the Black Knight from Can Tire or Home Depot in BC. There are now a number of one part acrylic coatings available for exterior use. The Black Knight stuff is about as thick as a thicker paint.

Canvas soaks up a lot of paint, so much that the coating weighs as much as the skin , using 3 coats for the hull and deck. Historically canvas covered canoes were coated with a filler of some kind to fill the weave and then painted with a marine enamel. Skin kayaks are much more flexible so marine enamel is not recommended as it dries too hard and would crack. Regular exterior latex paint would work fine on canvas but would take many coats to fill the weave . You could add chalk powder to the paint to help fill the weave.

I usually use 3 coats on deck and sometimes more on the hull.

: I am currently building a skin on frame in my attached basement/garage. I
: would like to kill the weave and paint with anything that will not affect
: the health of my wife and cat. I have a respirator but do not want my
: family to have to wear them. (Do they make them for cats?) The half pint
: of marine enamel that I used to paint the frame was bad enough. I know
: that latex paints are not technically waterproof but was wondering if
: anybody has used an industrial/flexable latex coating or anything else
: that might be suitable for my needs. I do not mind a higher maitanence
: tradeoff for a less toxic working environment. I can not work outside
: until the spring due to the low temp in Victoria, B.C. at this time of
: year.

: Thanks in Advance, Curtis