For an optimum polishing result of glass edges or bevels, the use of a liquid solution of polishing powder with water is recommended.
Such polishing liquid should be sprayed with a certain pressure between the glass and the polishing tool.
The recommended tools for this purpose are synthetic felt wheels, which are saturated with this polishing liquid.
The final polishing result is mainly determined by the quality of the polishing powder and by its concentration in the liquid.
This polishing powder for optical purposes of non-porous materials, is a relatively rare natural product that is extracted in quarries and that primarily consists of a mixture of oxides.
The total of oxides in the polishing powder is called "rare earth", named after its limited availability.
The main active component of these oxides for the polishing of glass is cerium oxide (CeO₂).
The quality of the polishing powder is determined by the total concentration of oxides (TREO = total rare earth oxides), and the concentration of the cerium oxide with respect to the total amount of oxides (CeO₂ / TREO).
For polishing of glass edges and mitres, the CeO₂ / TREO ratio should be at least 50% in a TREO of approximately 85%.
For bevelling, a minimum CeO₂ concentration of 65% is recommended, in a TREO of at least 90%.
The feed speed for polishing powders with high TREO (usually white in colour), is considerably higher than for powders with a low TREO.
For example for straight bevels with a width of 40 mm, the recommended feed speed with low TREO is approx. 1,0 - 2,0 m/min, while with powders with high TREO, this feed speed can be approx. 2,0 - 4,0 m/min.
Furthermore, for polishing powders with low TREO, a higher concentration in the liquid is necessary.