I would just like to share this process that I use when cermarking Stainless Steel.
I'm not sure if this improves the marking on brass etc, but would be keen to find out.
Following a recent thread concerning marking of larger / thicker plates, all of the suggestions related to slowing down speed / increasing dpi etc.
All this does, is increase the heat at the metal surface where the laser strikes.
I had a client request a photo and text etched on to a large 1/4" thick SS plate supplied by him.
I was concerned about the etch not 'taking' to the metal properly...
so I preheated the plate after applying the cermark in a toaster oven.
The results were amazing. I have done several cermark jobs since and I always preheat after applying the cermark, and the difference is vey noticeable, it also ensures the cermark is completely dry before marking.
On one larger job I also used an air/heat gun to re-warm the plate during a pause in the job, again keeping the material hot.
I hope this info helps, it really is worth a try, and does make the result more consistent and reliable.
(My toaster oven is a $50 cheapie we use for surface mount pcb soldering as well).
Cheers to All.
Chris