It is known to provide an inlay on a substrate such as a plaque of plastic material or a plate of a material like brass or other metal, in which a recess is first provided on the substrate, and then a mixture of slow-setting epoxy is placed into the recess and allowed to harden. In this conventional process, a particular problem is encountered, having to do with the fact that the epoxy, as it hardens, generates tiny bubbles of gas. While the epoxy mixture retains its original liquid consistency, and before it begins to harden to any appreciable degree, the tiny bubbles of gas that are generated by the chemical reaction between the resin and the hardener can float upwardly toward the free surface of the epoxy. However, as the hardening process continues, bubbles of gas continue to be produced, and a point is reached where the hardening process has so increased the viscosity of the mixture that the tiny gaseous bubbles can no longer rise through the epoxy, and become trapped. As a result, the final inlay resulting from the hardening of the epoxy is riddled with tiny bubbles constituting a multiplicity of small voids throughout the epoxy.
In the final finish step for the inlay, any excess epoxy (projecting above the plane of the top surface of the plaque or plate) is removed by sanding or grinding, and then, if desired, a final polishing step can be included in order to give the epoxy inlay as smooth and glossy an appearance as possible. The problem, of course, is that the tiny voids throughout the epoxy, resulting from the gaseous bubbles, cause irregularities in the form of tiny pockets covering the entire surface of the smooth (and optionally polished) surface. This makes it impossible to provide a smooth and integral (unbroken) polished surface.