I've been using this in lieu of thickened epoxy on a number of projects, and it occurred to me that is might also be useful as a skin coating. So I tried it, on a test scrap. What is it? It's PL Premium Polyurethane Construction Adhesive.

This is a completely waterproof, very strong adhesive that sticks to a large variety of substances, including wood, metal, fiberglass, masonry, ceramic tile, marble, etc. It also adheres extremely well to fabric, as it turns out. It's thick, gap filling, and comes in a tube that you use with a caulking gun. There are two tube sizes, and the smaller produces a bead 30 lineal feet long.

I tried it on a scrap of 8oz polyester, which I commonly use for skinning kayaks. A 2-3" bead covered about a square foot of fabric, and was best applied with a rubber spatula. I put on a single coat. It spread quick and easy, though it was difficult to tell if I had completely covered an area. It only just changed the fabric color - making it look like it had been soaked in water. The glue did not migrate through the weave to the opposite side of the material. It filled the weave on the one side very well.

I let it dry for a few days (though dry time is much less), then examined it. The fabric was stiffer, but still easily fold-able. It did not hold a crease, and no cracks or chips were observed. I could not scrape it off with a fingernail, a board or then a brick. The finish is slightly glossy.

Then I tossed it into a tub of water - for 4 days. That's at least 86 hours longer than I've ever had a kayak continuously in the water, FYI.
After 4 days, the fabric and coating was entirely unchanged. It was still flexible, I still could not scrape off the coating, it showed no signs of delamination, cracking, peeling, etc. Making a cone of the scrap, and filling it with water, still produced zero leakage.

I do not know anything about its UV resistance, or its paint-ability. I surmise that dyeing the skin first - a common practice - would be the way to go for various skin colors. When I get time, I'll paint some and see what happens. It is "moisture curing," so perhaps mixing acrylic or watercolor paints into it might work to tint it. I'll have to experiment with that, too. Calling the manufacturer seems like a good idea, as well.

In sum, my initial trials are leading me to the conclusion that this could be a very viable, easy to apply, very tough and - at $3-4/tube - not particularly expensive skin coating option. I have a boat in mind that I will try it on, and I, of course, invite any of you to try it, too - on a piece of scrap, or perhaps an entire boat.

Dave Gentry

Specs here:
http://files.buildsite.com/dbderived-f/pl/derived_files/derived267834.pdf