[Stefan] of CNC Kitchen has an informative video describing his experiences with trying to cleanly laser-mark 3D printed plastics using different methods, and it also happens to be a fantastic tour of all the different laser options available to hobbyists and workshops these days.

Laser marking is a fast and effective way to put things like product names, serial numbers, and other information on plastics. [Stefan] wondered whether laser options would be capable of creating clean and professional marks on 3D-printed items, and approached things with his usual attention to detail.

How does a laser mark plastic? When the laser hits the material, its energy is dumped into it and can cause pigment bleaching, microfoaming, charring, melting, or ablation (vaporizing) of the surface. The goal is to have a combination of laser and material that delivers a crisp, high-contrast result.

There are several kinds of laser technologies easily available today, and of course a variety of filament types. [Stefan] printed a whole bunch of different PLA, PETG, ASA, TPU, and polycarbonate samples in different colors and tested them with different laser machines, including:

• UV laser (355 nm wavelength)
• Blue diode laser (450 nm wavelength)
• MOPA fiber laser (1,064 nm wavelength)
• CO₂ laser (10,600 nm wavelength)

So is it possible? Yes, but it’s still a bit of a fussy process. There isn’t a one-size-fits-all solution for marking plastic, because results depend a lot on the the right combination of laser type, settings, and target material. That being said, [Stefan] was able to obtain some really great results.

Overall the UV laser was the most suited to marking 3D-printed plastics. [Stefan] says it produced the cleanest results on the widest range of materials with the least fiddling. The MOPA fiber laser also worked, but is clearly more of a metal-marking tool. We’ve seen them etch super-fine PCB traces and while great results are possible it isn’t quite in its element with plastics. Other lasers could get good results under just the right circumstances, but are overall best suited to cutting tasks rather than marking thermoplastics.

Check out the video below for the full details, including some really fantastic closeups.