Metal etching can be dangerous! If you’re going to try this, make sure to read all red the warning text at the bottom of the Edinburgh Etch page first!
Also note that copper is reflective. Laser forum users warn that there’s a risk of the beam bouncing off the copper and back into the laser head. I scuffed the copper prior to lasering to avoid this, but I’m not certain how big of a risk this is.
One thing I’d been really excited to try on my Glowforge was etching metal. Of course the Glowforge doesn’t etch metal directly, but there are a lot of posts on the Glowforge forums where people had spray painted metal and then etched it. I was really curious if it was easier to do than the laser transferred resists I’d been using. So I searched the forums for all the information I could find on methods people were using, and gave it a shot.
I started by using a matte black spray paint to spray paint some flat pieces of copper and brass. I let it dry for 24 hours.
I found settings by etching and scoring a test piece. The settings that worked best for me were:
As I’d seen on the forums, after engraving there was a thin residue of paint left over. I started rubbing a spot in the middle with fine synthetic steel wool; you can see a shiny spot where I removed the residue. I kept going until I had gotten all the residue. I wasn’t able to preserve all the fine details while polishing, but I did remove the pixellation in the etch:
Since I had spray painted both sides of the copper and brass pieces, I didn’t need to add any additional resist. I put them into some Edinburgh Etch for a few hours.
After removing from the etch, I used acetone to remove the spray paint. At this point I saw that the photo etch looked really cool from some angles, but really incomprehensible from others.
I realized I could put a patina on the metal before removing the spraypaint, and it would only darken the etched area. I did this with JAX Brown.
After drying the patina and using acetone to remove the paint, I finished with clear Krylon spray.