Engraving wine glasses with an LP4 Safeguard. The mark comes out flaky and chipped rather than a nice frost, and sometimes bits of the surface come away completely.
Tried lower power, higher speed, both. Same result, just fainter.
Clear glass keeps chipping — what am I doing wrong?
3 replies
Priya RamanModerator · LP4 Safeguard2 weeks agoThat's normal glass behaviour, not a settings fault. A diode laser doesn't really absorb into clear glass — what you're seeing is thermal shock fracturing the surface, which gives you that flaky chipped look.
Two fixes, both cheap:
- Coat it. Dish soap on a sheet of newspaper, laid wet over the area, or a proper laser marking spray (the moly-based ones). The coating absorbs the beam and gives you an even frost. Wet paper towel is the classic version and it genuinely works.
- Defocus very slightly (0.5–1mm) to spread the spot. Sharp focus concentrates energy into a point and encourages chipping.
Settings that work for me on wine glass with a wet-newspaper mask: 60% power, 2500 mm/min, 1 pass, rotary on, air assist off (you don't want to dry the paper mid-job).
Also: cheap glass chips more. Thicker restaurant-grade tumblers behave far better than thin supermarket wine glasses.
Hugo MarchandLP4 Safeguard2 weeks agoWet newspaper. I feel silly. Tried it this morning and it's a proper even frost. Thank you.
Marcus ValeAdmin · LP52 weeks agoWorth adding for anyone finding this later: coated/painted glass (like the powder-coated tumblers) behaves completely differently — that's paint removal, not glass marking, and it needs much lower power.