Six wine glasses for a friend's anniversary. My first attempts chipped and flaked because a diode laser barely couples into clear glass — what you get is thermal shock, not marking.
Fix, courtesy of this forum: wet newspaper laid over the area. The paper absorbs the beam and transfers heat evenly into the surface, giving a proper frost instead of fractures.
Settings
60% power, 2500mm/min, 1 pass, rotary on, air assist off — airflow dries the paper mid-job and you get a hard line where it stopped working.
Keep the paper properly wet, smooth out every air bubble, and re-wet between glasses.
Results
Even frost across all six. Two of the earlier chipped attempts are in the last photo for comparison — same file, same machine, no coating.
Thin supermarket glasses still chip more readily than heavier ones, coating or not.
