Ya Raptor bed liner cracked badly. I think this liquid rubber product is going to work well (meaning last and not crack)....wish I had known this before wasting the time and money on Raptor. Hopefully my lesson will teach others what not to doCool project, thanks for the update!
As I recall you used bed-liner directly on the plywood at first? And it cracked? They don't make ply like they used to, unfortunately...
I built one in the 90s that was 2.7mm luan ply sandwich, with just "epoxy paint" coating it. Even though that ply was cheap it was pretty decent quality back then. That didn't work either, but because the paint wasn't as waterproof as I thought. Really a stupid move as I should have researched that better, but I was in a hurry. I later coated it with Snow Roof, which sealed it for years.
I think epoxy and a layer of fiberglass on the outside is the best bet for plywood. I later built one like that and it was solid as a rock and waterproof.
I would check out the liquid rubber stuff: https://amzn.to/3Lap4kq (it comes in a gallon size for testing). I would apply directly to untreated wood so it soaks in a bit which will help durability.I used ALS, Advanced Liner System, on my truck/canopy job. The only issues in use were where I failed in the prep - however the product was extremely difficult to work with, setting up very quickly even with reduced catalyst in cool temps. I can't imagine using a spray gun to apply it.
I've got another project, and am looking for an easy to apply product. As it won't see the wear of bedliner, I'm thinking there might be a cheaper product available that would be durable enough.
If you are coating plywood, you have to worry about cracking of the wood and the crack propagating the the outside. If you use quality marine ply that's less of a concern. Epoxy and fiberglass over ply is the best, but you need to paint over that as well.I've got another project, and am looking for an easy to apply product. As it won't see the wear of bedliner, I'm thinking there might be a cheaper product available that would be durable enough.