Jimbo,
Thanks for the response.
>... you don’t want to use a water based adhesive if you can help ...
For various reasons. I agree.
> ... regarding using foam core as a substrate. Over time I have had a few bad experiences with that and canvas.. Especially on larger pieces.. they warp over time. We figure that this is due to difference in shrinkage / expansion of the canvas & the substrate and the canvas always wins. ...
I agree there are risks to it.
The expansion and contraction of the materials is probably mostly due to humidity. I wonder if both sides of the foam core and the canvas face are sealed if that makes a difference. The canvas will definitely be sprayed with Print Shield. Whatever is used for the bonding will probably also seal those surfaces. That leaves the back to be dealt with, if sealing to block humidity is an issue.
My latest thoughts include using low viscosity epoxy primer that can be applied with a roller. I've made camera and lens cases for years by using epoxy and nylon cordura fabric on soft polyurethane pieces cut from cheap sleeping pads sold at places like Walmart. This results in a rather strong structure. I think it would take care of the softness of the foam core. If the foam core were coated with the epoxy primer on both sides, it would be rather humidity proof and stiff.
For unglazed silverprints on mat board, I've also used small wooden stays epoxied to the back to stop the warping.
> … It’s simply about what your market is and what you can pull off ...
So true.