Durham’s Water Putty. I can’t say that I am a big fan. Even mixed with water color paint to match the color of the wood, it dried way lighter. I guess I should have experimented before applying, but based on the rave reviews I found scattered about the interwebs, I thought it would work better. Anyway, I managed, with a scrub pad and some water, to get rid of the worst looking spots and then sanded the rest. There are still some places I am not happy with (see photo,) but I am not going to get too bent out of shape about it.
After that, I finish sanded with 120 grit on the orbital sander. This worked great except that in the stern of the kayak there is some horizontal grain (see next post) that the orbital highlighted by removing more of the softer parts, while leaving the harder parts. I couldn’t really see it, but I could easily feel it with my hand and from prior experience with finishing wood, I know that if you can feel an imperfection, it will be glaringly obvious under a glossy coat of varnish. This is common with horizontal grain and a reason you should try to avoid it. Anyway, I put some 80 grit paper on my fairing board and after about 20 minutes of sanding, eliminated most of this unevenness.