To update my progress on re-felting my freestones for the third time...
As I said before, I bought natural, high density felt (actually 5/8 in thick) which, when I tried it last year, wore away very quickly. I still had lots of felt left, so I wanted to try again.
I bought a quart of oil based liquid polyurethane from Home Depot thinking it might be enough for a couple of sets of felts. After a successful test on a small piece of scrap felt, I started pouring it on to felts that I had cut to a size just slightly bigger then the boot prints. I was shocked to find myself pouring the whole quart on without it being enough. The felts could have soaked up more. The VOC stink was terrible. Took 3 days before I could go near them.
Instead of letting it cure completely, I just waited until they weren't tacky anymore, and glued them on to the boots using the marine grade Goop. Since Goop is also polyurethane, I wanted the glue and the liquid polyurethane in the felts to bind and form a single piece. Taking no chances, I used the equivalent of a whole tube of glue for each boot. I have had them fall off before because I didn't use enough glue. I applied a layer of glue to both the surface of the boot and the surface of the felt, let it de-gas for 10 or so minutes, and then applied more glue before putting them together. The felts didn't absorb as much glue this time, I think because of the pre-treatment with the liquid.
The cure time is critical because exposing polyurethane to water prematurely causes it to go a milky colour and fracture. Because the solvent has no where to go except through the felt, it takes a long time. The way I think about it, if you can still smell it, it's not finished curing. I would say at least a month, if not 2.
Total cost for materials for one pair came to about $110. But these are twice as thick as most replacement felts, and I'm hoping they last a long time. I will do another update after I try them out and let you know how they work on slippery rocks.