Glass, Stone & Ceramic Laser Engraving

Not on a CO₂ machine, and we will not pretend otherwise. A CO₂ laser frosts the surface of glass — rapid local heating fractures a very shallow layer, which reads as a clean white etch. It does not pass through. There is a real physical process for separating brittle materials by controlled thermal stress, but it is not what a shop-floor CO₂ engraver does and it is not a Boss capability claim. If your job genuinely requires cut glass, that is a glass-fabrication process, not a laser purchase. If it requires marked glass, a CO₂ engraver or a UV marker is exactly right.

Too much heat in one place. The frost you want and the chipping you do not are the same mechanism at different intensities — controlled surface fracture versus the surface flaking away. So the fix is almost always less power and more speed, not more. Boss’s published starting point for glass is 27/25/20% at 325 mm/s, which is deliberately gentler than most materials. Beyond settings: glass quality varies, thin or curved stock is less forgiving than thick flat panels, and a piece that is cold to start with will behave differently from one at room temperature. Test on the same product before a production run.

If you are doing drinkware, bottles or stemware, yes — and it is not an optional refinement. A rotary turns the workpiece under the beam so the artwork wraps evenly around the curve; without one you can only engrave the small area that stays near focus. Two things decide whether it works: entering the diameter correctly so the design does not stretch, and keeping focus consistent as the surface curves away. Check interior height clearance too, especially on a desktop machine — tall stemware is the constraint people discover late.

Dark, fine-grained stone gives the best contrast, because the engrave works by lightening the surface — a white mark on black granite or dark slate reads far more strongly than the same mark on a pale stone. Boss publishes granite settings at 40/25/18% and 275 mm/s, which is high power and slow speed compared to glass; that tells you most of what you need to know about how much harder stone is to mark. The practical caution is that stone is a natural material with no specification: two slates from different suppliers, or two slabs from the same quarry, can behave differently. Buy a little extra and test.

The image is rendered as thousands of tiny frost dots, so the work is nearly all in the artwork. Convert to greyscale, push contrast harder than looks right on screen, and apply a dithering pattern suited to the material — a straight greyscale gradient will come out muddy because the surface can only really do “frosted” or “not frosted.” Dark polished stone is the most forgiving substrate for photo work. Then test at size: what reads beautifully on a 4-inch tile can turn to mush scaled up or down, since the dither pattern scales with it.

When the detail you need is finer than a CO₂ frost can resolve, or the part cannot take the thermal shock. UV operates at roughly 355 nm and marks through a photochemical process with a minimal heat-affected zone — “cold” marking — which is why it is standard on medical, electronics and precision ceramic work. For awards, drinkware, slate boards and signage, a CO₂ engraver is the right and far more economical tool. For fine glass, precision ceramic, or anything where a chipped edge is a scrapped part, UV earns its place.