Pinned because it comes up every week and the answer never changes.
Never cut or engrave these:
- PVC / vinyl / faux leather with PVC backing — releases chlorine gas. It will corrode your machine's internals and it is genuinely dangerous to breathe. A lot of cheap "leatherette" is PVC. If the label doesn't say it, test a scrap with a copper wire flame test or just don't.
- Polycarbonate (Lexan) — melts, flames, yellows, and blocks IR badly. Cast acrylic (PMMA) is what you want.
- ABS — cyanide compounds and a horrible melted mess.
- Fibreglass / carbon fibre — glass dust and resin fumes.
- Coated carbon fibre, mirrored acrylic engraved from the back, anything containing chlorine.
- Any material you cannot identify. "It came off a pallet" is not a material spec.
Always:
- Wear glasses rated for your wavelength. Diode machines are 445–455nm; fiber is 1064nm. Diode glasses do not protect against fiber. The rating you want is OD5+ at that wavelength, and the number should be printed on the frame.
- Extract to outside, or run a filter with real activated carbon. An open window is not extraction.
- Never leave a running machine unattended. Keep a CO2 extinguisher or a fire blanket within arm's reach — not in another room.
- Air assist on any cut. It keeps flame off the surface and stops most flare-ups before they start.
If you're unsure about a material, post the product link here and someone will know.
