as title tittle says, im trying to print a very dense pcb layout on a termal paper (https://www.tme.eu/en/details/tes200/materials-for-pcb-production/). I'm using a laser printer, as it is mandatory. Problem is, you can see some little grains all over the printed pcb. What can i do to prevent this? Is this due to dust/grease on the paper or bad printer/printing method.