I wanted to see what would happen if I put a ceramic (stoneware) dish under the lazzzor. I started with the settings for etching glass, but the laser handbook only recommends raster settings, and I wanted to try vector engraving as well, so I tried a bunch of variations.
In the above image, I rubbed a bit of pencil graphite into the engravings to make them more visible. My favorite vector setting was 100% speed, 50% power (on the 35W Epilog). Slower speed or more power raised an ugly lumpy bead of molten glaze, but 100/50 gave a nice smooth scratch.
For my raster test (lower left in the image), I used the recommended settings for glass at 600dpi: 35% speed, 10% power. It looked just fine so I didn’t try any other settings.
I thought maybe I could melt through the colored glaze to reveal the white ceramic underneath, but that didn’t work.
The zigzag line in the above image was engraved at 75% speed/100% power, and the straight line at 14/100. Neither was able to make a white line through the blue glaze. I was afraid to go any slower, because there was already quite a lot of heat building up. Also, I’m thinking of doing this in bulk to a lot of dishes, so I’m ruling out any technique that goes slowly (and thus costs more).