When lasering slate you can just laser right on to it. for best results i add a layer over it.

Slate nothing added to it

Slate Coated

• Adding a layer will keep it a full black look and when it is laserd on will give it that shape look and clean finish this is what i coat with.

Coating

• Working on what look you want this is the best way i have found to get that really sharp look and clean finish. right off the laser. Here is what i do mine at.
  1. Laser Grbl
  2. Speed 2200
  3. Min power 250
  4. Max power 255

This will not work for all you have to find a speed you are happy with and what look you want.

Coated Slate Laserd

• As you can see end result is really sharp. This is the only way i have found of doing it if you coat after you have laserd you lose some of the look of it.
  Here is a video i did about this.