I haven't used ppg but,I have used pearl powder with HOK,Do not sand on it!Spray your pearl then,spray another couple of coats of straight clear.then you can sand.When you spray your pearl,be careful,the more you put on,the lighter it gets.Hold your gun back and try to dust it,if you don't get complete coverage,wait til it tacks and then hit it again,if you try to spray on more before it tacks,you'll have a mess.The pearl doesn't run but,it will blow too close together and looks like a run.Been there,done that.