Good morning, recently installed a penny floor using Glasscast 3 and couldn’t be happier with the result. Came up with idea of putting map in the entry floor with some postcards and pouring Glasscast 3 over it. Have a few concerns/ questions- there are going to be areas of the underlayment (3/8” AC plywood) that will not be covered by the map/ postcards. My thought was to simply paint entire area either white or black with latex paint to seal wood and then lay down map & postcards. Is it ok to use latex paint for this or should I use something else. Should I glue down the map & cards prior to pouring to eliminate shift or even product getting under items and if so what should I use for adhesive? Thank you in advance for your time, Mike.

No, anything without a separate hardener component is somehow soluted and will outgas for a long time. You could use the epoxy you already have with black pigments to get a black 2k paint.