What metals should I avoid sharpening on CBN?

Stay away from soft steels; aluminum, brass, and high carbon tools to name a few. A good rule of thumb is if the item being ground throws off a lot of sparks, then don’t make a steady habit of grinding it. Occasionally is ok as long as long as you go back to sharpening high quality steel so it will help clean out the pores in the wheel. Using Wonder Slick Stick will help keep any softer metals from loading the wheel.