I wouldn't bother if its anything like monty brake spray. Horrible stuff, makes a mess of your rim.  I never wanted a grind, thought it was pointless, and stuff. But i persuaded myself to do one, but with a stanley knife. Then i got a grind, and haven't looked back.  Tar is also good for on/off braking. Not good for manuels or what not.  My advice is not to spray that on your rim. Try Zoo! greens, they are pretty rad without a grind or tar.