Hatch Covered? It Depends ...

We decided some time back to cover the hatch first.  It is the smallest piece of Filon to apply, and we had the best opportunity to control the process (aka learn.)

I wanted to use Titebond FRP Solvent-Based Adhesive, but that product is apparently contraband in Connecticut.  Given the VOC content of the product and the State regulations, it cannot be shipped into the state.

Sigh.  It is the perfect product for what we need to do.

Okay, punt.  Go find a suitable replacement.  Well, all the replacements are labeled "interior only."  No surprise there, since they are all latex or acrylic-based.  

After much cogitating on the issue, I picked up a one-gallon pail of Henry's FRP-444 adhesive.  This stuff is supposed to be good for adhering FRP (of which class Filon is a member) to plywood.  It sports a reasonable open-working time.  What could be better other than an exterior-specific solvent-based glue?

Well.  We rehearsed the process, applied the adhesive, placed the panel, and were quite surprised that the adhesive failed to "skin over" as advertised.  It also failed to achieve any apparent tack.  Had we not used band clamps to force the FRP to comply with the curve of the hatch, adhesion would probably not have sufficed.  As of this writing, some 9 hours later, we still are uncertain that the adhesion between the Filon and the plywood is working.

Why?

Possible explanation #1:  At the time we applied the adhesive this morning the temperatures were in the 60s.  The product specifies that the adhesive and the panels be above 70 degrees for 48 hours.  I doubt this is the issue.

Possible explanation #2: The product is specified to have a one year shelf life if unopened.  The date code on the container does not make clear what year applies.  It may be very old product.

What's next?  We'll leave the clamps in place until we feel it safe to remove them. Should the "globs" at the edges fail to solidify, we will have little faith that the adhesive will actually cure, and may need to peel the covering off the hatch and proceed to remove all the adhesive residue.

I hope it doesn't come to that!