You need to put sand between the pieces of glass too or else the epoxy will ooze UNDER the glass and ruin the piece. LET IT HARDEN AT LEAST 24 HOURS! Then turn the panel over and pour the other side. When you turn it over you are pouring epoxy into the spaces where the sand used to be. If the glass is 1" thick then the sand comes about half way up the piece of glass. When you turn it over that first time the sand falls out and you need to replace it with epoxy.
Do you have to apply sculpy to the new side of glass once the frame is turned over to fill with epoxy? Or, do you just have to pour the epoxy carefully so as to not get it on the glass face?