Saw this video on how to add colour to your laser engraving. It involves melting powder coat paint.
Youtube obviously sends us the same videos.
You'd need to turn down/off the air assist on the laser, since the one at the space is quite aggressive. It'll likely blow the powder out of the engraving before it has a chance to soak in.
I have some small containers of powder if someone wants to try it, they were super cheap at Princess Auto when I was experimenting with the shake-n-bake method of powder coating.
I might be interested in trying that out.
Pierre, I was thinking of a way to do this with metal. If the metal were powder coated first it would provide a base layer. Then the graphic could be dithered into the powdercoat. The idea would be to remove only some of the PC. Then the new PC could stick to the base layer PC instead of having to stick to the metal.
Air assist is easy to bypass now. We have the central air compressor set up. The air for the laser is controlled with a switch.
I'm not clear on what type of outgassing you'll get doing Laser ablation of the powder coated surface. I'm guessing that the cheap powder I've got is either an epoxy or a polyester, but princess auto provides zero information (not even an MSDS) for it.
I'd be tempted to carefully pre-heat the metal almost to the point of melting the powder (or sit it on a hot-plate) to minimize the amount of time it takes to get your bond.
Maybe consider using something other than the powder for your mask coating that you are burning off. I had very good results burning off water-based acrylic paints or masking tape in the past... You might be able to do some very nice work by laser-cleaning mask off the metal, all the way down to the base stock, shake-n-baking the powder into the cleaned areas, then removing the mask?
I pulled the MSDS for a few random powder coating powders. Several of them outgas cyanide when burned. Maybe don't do laser ablation of powder coats unless you know what powder you are using.
There are safer ways to mask your art.
I found a video for testing plastic for chlorine. https://forum.makerforums.info/t/a-quick-way-to-see-if-plastic-has-chloride-in-it/85606