BTW - rognvald - the 635 resin does not blush so there is no need to worry about adhesion of successive build-ups. For Sanding
& grinding, I use a 9" OD right angle buffer with a 40 grit carbide semi-rigid wheel
. The wheels are standard at Home Depot. I used only one of these wheels on the entire bottom of my 58 foot boat to put on the new bottom. Very aggressive and durable. The grinderis shown in one of the photos along with the aluminum
angle I used for leveling my lines. Note that if you work the angle like a concrete screed that black spots are left at high places. Makes it clear where to work. I wish you success.