The evenly flat surface of flat glass actually requires no post-processing – unless your application requires encoder, slider or fingertip guides. These are ground into the glass – which means that glass is removed evenly in thin layers. Afterwards, the glass is no longer transparent at these points.
If the indentations in the glass are to be restored to their original transparency, the areas must be polished. The unprinted cover glass on the left in the picture shows the difference between a purely ground haptics – and the ground and polished indentations of the finished product on the right.