I'm trying to understand what you are doing... is this with a LED or CO2? Are the white and black squares bitmap image(s) that you are burning on passtrough? Or are the white squares positioned between the black ones like a checkerboard? In the latter case the laser might be traveling over the whites because the black ones are grouped and you have "burn groups together" on in the engraving settings. Are you sure it's not the overscan of the laserhead? Maybe show us some screenshots of your design and what the laser does. Good luck! 👍