After I finish cutting the plaque, I put masking tape on the reverse side of the plaque where the pattern and cuts allow. I place matching pieces on the backerboard. I then apply the finish to the plaque. When this is done, I spray the backerboard with flat black. When everything has had sufficient time to dry I strip the masking tape off of both pieces and use Titebond III to adhere the two pieces. I place the finished plaque face down on on a very clean tablesaw table covered with wax paper. I strip off the masking tape off the plaque and the backerboard, apply Titebond III and use some weights on the backer board to hold the two together until the glue is cured. This gives plenty of clear wood for the Titebond to do its work.