The vast majority of commercial leather is chrome-tanned, including furniture and automotive offcuts. In a laser, that leather releases hexavalent chromium, a recognised carcinogen. No setting makes this acceptable.
What actually happens
Beam heat converts the trivalent chromium of the tanning into hexavalent chromium, which ends up in the smoke and in the dust deposited on the bed and the part. A domestic carbon filter does not stop it.
The risk is not immediate but cumulative: repeated low-dose exposure, exactly the profile of occupational cancers. That is why serious workshops refuse this material, even at a client's request.
What to use instead
Vegetable-tanned leather engraves and cuts perfectly, with a warm leather smell and deep brown contrast. It is the only animal leather to use in a laser.
Plant-based leather (cork, apple or grape) and PVC-free synthetic leather are also compatible. Always check the supplier datasheet: “PU leather” on a PVC backing must be refused.
How to spot chrome tanning: the cut edge is uniform blue-grey, whereas vegetable-tanned leather shows a beige to light brown edge. When in doubt, ask for the datasheet — or cut nothing.
Every figure on LaserSettings comes with the machine, the laser source, the material and the thickness it was tested on. A setting published for a 10 W diode says nothing about a 40 W CO2, and a setting for 3 mm says nothing about 6 mm: check those four things before you copy any number.
Settings are confirmed or disputed by the members who reproduce them, so reliability comes from cross-checking rather than popularity. Photos of the result — cut edges, engraving shades, scorching — tell you more than a single number found on a forum.
Whatever the material, treat a published setting as a starting point: run a small power/speed test grid on an offcut, clean the lens, redo the focus, work with fume extraction and air assist, wear glasses rated for your wavelength and never leave the machine unattended.