How do you achieve sharp white raster engraving on substrates with high color density?

Using the bottom-up engraving method minimizes the redistribution of color residue onto the white surface. This method can minimize the amount of residue being exhausted over previously engraved material, which may re-deposit on the warm core and make post-fabrication cleanup a challenge. You can change the orientation of your laser to bottom-up engraving from the Advanced tab in your print driver.

Increasing power in 5 percent increments can also be helpful. Due to the color density of some of the more vibrant color selections, I recommend running two passes to achieve optimal results. The first pass should ablate the majority of the micro-surface while the second pass removes any residual colorant to offer you a clean, sharp result. 

-Bobbi Payne, Rowmark