Any roughness was levelled by polishing with ivory or a smooth shell.
The deceptive effect is in some cases heightened by cutting over and polishing by hand the pressed surface.
Polishing is effected by wooden wheels fed with wet pumice-powder and rottenstone and by brushes fed with moistened putty-powder.
This operation, like all the subsequent steps in the polishing of the glass, is carried out by powerful machinery.
This smooth surface is then brilliantly polished by the aid of friction with a rubbing tool covered with a soft substance like leather or felt and fed with a polishing material, such as rouge.
