When cutting thicker acrylic, I have found multiple passes works when a single pass just leaves charcoal. However, the glowforge software makes all the passes on a shape then moves to the next one. It would be very helpful if the multiple passes would complete all the the shapes of a color before beginning the next pass. This would allow the material to cool and make a nicer cut.
I am currently, duplicating all the shapes, changing the color, then making one pass with each color. This works really well for me.
I just wish we had that option in the software, seems an easy fix.