We are making travel trays for paintings to be transported and then stored. I was going to use 1/2" GatorBoard for the trays, hot glued, edges taped, and ethafoam pads throughout. But, now I realize that Gator board is not "archival." And I have not found archival 1/2" foam board. The paintings will be separated from the GatorBoard tray with ethafoam pads. Given that separation, is there a concern using the GatorBoard? They paintings will be stored in the travel trays for anywhere from 1-5 years. What material should I make my trays from? Please advise. Thanks, Tim