Reminded by a recently-discovered video of a very powerful rust-obliterating laser, Jen and I pulled out a few pieces of copper from one of her previous projects. Two pieces of copper, a teardrop with a light acquired patina and a scrap piece, two hearts cut out of the center, with an applied patina. Our plan was to try to engrave away both patinas, using a diagonal line pattern we’d used before for the iron bar I use to keep projects in place on the laser bed.
Once I had both pieces on the laser, I engraved that pattern on the front surfaces, using default settings (100% power, 100% speed). I was surprised to see that the teardrop didn’t show any sign that it had a laser fired at it. The heart cutout’s patina did seem to be burning away, but it was only burning away the bluish top layer, leaving surface stains. I decided to increase the power.
At 100% power and 10% speed, engraving the full surface of both pieces took twenty minutes. But the results, sadly, were almost identical: the teardrop remained unscathed while the heart cutout was visibly patterned by the process but still discolored underneath.
Somewhat disappointed by the finished look, I took a treated polishing cloth we’ve had lying around and went to town on each piece. To my surprise, neither polished up in any appreciable way. It was an old cloth, so I figured it might just be worn out. But it polished my metal slime just fine! Perhaps it’s down to the different metals.
Either way, Jen came to the rescue. She offered up some powdered cleanser and a toothbrush, and I got to work scrubbing both pieces clean. This worked much better, even if it was a messier process than the polishing cloth. The best part is even that abrasive process didn’t remove the patina that wasn’t already removed by the laser, so I was able to get a brilliant shine alongside the bright blue of the patina.
The heart cutouts after scrubbing with Bon Ami. It didn’t remove the patina at all. How shiny! 
Jen’s heart cutouts before scrubbing them down with Bon Ami. 
Jen pulled out some Bon Ami powder cleanser and a toothbrush, which fared much better than our special polishing cloth. 
Using the laser to burn away patina with mixed results. 
The recently-polished bottom of my metal slime. Just for funsies. 
One out of two ain’t too bad, right? 
The diagonal line pattern is the same one burned into the iron bar holding these pieces in place. The polishing cloth I’ve used for years to keep my metal slime shiny didn’t do anything to the copper pieces. 
After engraving, one piece clearly shows the pattern while the other does not. 
The bluish applied patina burned away, but there was still a lot of discoloration underneath. The light acquired patina on the teardrop did not react to the laser whatsoever. 
The front side of the copper pieces, before any engraving. 
The back of each copper piece. The teardrop has the name “Jennifer” written on it, but it’s hard to see.
I love the fact that you’re willing to share projects even when they don’t work out the way you imagined.
Thank you! Yeah, that’s bound to happen when I dip my toes into unfamiliar waters. I’ve done next to nothing involving patinas beyond cleaning that little metal slime figurine. I imagine a lot of the conclusions I reached would have been obvious for someone more familiar with the metals. But hey! It’s a learning experience. 🙂