EDIT: Cropped and increased the size of the pictures to give you a better look.
EDIT again: I should have mentioned that I am using the spray-on LMM6000 Cermark.
I have a couple of projects that I am working on for my parents, so I decided to test Cermark on some .02" thick aluminum engraving tags. Through multiple iterations, I seem to be getting the best results using 2 coats of Cermark at 600/Full. At slower speeds, there seem to be some artifacts created.
With 1 coat of Cermark, I had to use 300/Full, but did not get a picture of it, and while it was acceptable, it wasn’t quite as dark. 1 coat of Cermark at 600/Full creates more of a greyish text that is just barely readable from a distance.
Here are my latest test runs before cleaning off the Cermark:
And here they are after cleaning: