In the OP there was mention about using a 10W laser, what would be my adjustment for a 5W laser. Im thinking I would halve the speed at the same power?
For my 10 watt laser, I used the 1,500mm at 65% power recommended by Dskall. I also found that I had to use two coats of High-gloss spray paint that contained Titanium Dioxide/
I got good results with the RustOleum Heirloom White. The Cold Galvanizing Compound also worked. However, I got tired of the fumes from the paint and using lacquer thinner (@ $25/gal) to clean up afterwards so I made a water based version. I bought TiO2 on Amazon from Essential Labs for the recipe. The recipe has 25 g. TiO2, 25 g Tempera paint (helps suspend the TiO2 and gives some color so it can be seen on the tile), and 70 - 75 g. water. I mix well with a coffee frother and spray with a Harbor Freight touch up spray gun. This gave excellent results and all clean up with water and no solvents. Also cheaper than the Rusto paints. All this using 10W XTool D1 laser. Good luck.
These all turned out real nice with dark black etching and fill mode. The eagle was hard using grayscale. I tried all kinds of speed and % power trials with not a lot of success.
Failure is nothing more than a lack of successful attempts.