On a more positive note, I sheeted one side of the fin using the iron-on method, and it seems to work. On the other side, I'll use a thinner layer of glue (Titebond Original) and let it dry even more before ironing it. I had to keep the heat over an area longer since the glue was applied too heavily and still too wet. The cotton setting seems to do the trick.

Cheers,
Richard