Enrico Konig
Posts: 74
Joined: 2006-01-06
Location: Vancouver, BC
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Normally your 2 ply is done first. An urea formaldehyde glue (such as Unibond) would be definitely recommended, especially considering the bleed through you're going to get because of the pinholes. (I've never used pva for a 2 ply, and I definitely wouldn't use it if you had any seams because of the cold creep potential. And I don't use it on curved pieces such as what you're doing because of the greater springback than with urea.) Once your 2 ply comes out of the press, glue it up with the rest of your layers, again with urea formaldehyde. I have done this quite a lot as just one pressing, however, 2 ply & the rest, because it means one less pressing, less wasted glue, etc. But normally it is done separately. When the 2 ply comes out of the press, ideally it is pressed immediately with your other layers, as it will have a tendency to curl and will become brittle as the urea resin fully cures. But I have left 2 plies for several days, even longer sometimes, but had it under weight so that it didn't curl up. Just be aware that it will be a bit brittle when handling it. In some cases, as timing necessitates, I make the 2 ply before heading home for the evening, and then it will be fully cured and brittle by the morning, but will still easily bend to a much greater radius than your doors are likely to be. Shops with good quality sanding machines will sand the 2 ply before gluing it up with the substrate material(s), especially when it's going to be a curved piece, and this is one of the advantages of 2 ply. And I doubt if they're putting a 2 ply through the sander that isn't fully cured.
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