This is an operation to be specially carried out to obtain uniform matt or satiny surfaces.
For the micro-bead peening, glass microballs with grain: 40/70 microns – 100/200 microns – 200/300 microns are used according to the requirements and the use the finished product is destined for.
Aluminum dioxide is instead used for the micro-sand blasting. 
It is used in the optical field to make surfaces dull.

In conformity with the ASTM-D-1214-58 specification and UNI 5394-72 code.