Originally Posted by SimpleGreen.com
Simple Green has been successfully used by many woodworkers over many years as a good "spray - wipe - rinse" cleaner for saw blades. When pitch is fairly fresh (typically within a 12-hr period since deposit) it is fairly easily removed with Simple Green. Older, dried-out pitch is much more difficult to remove. We do not recommend long-term soaking of Carbide blades in Simple Green. Long-term exposure like this can possibly cause cobalt leaching that will, in turn, affect the integrity or carbide. Shorter term "spray/wipe/rinse" applications do not create that kind of problem.
It has been reported to us that long-term soaking of carbide blades covered with older, tougher buildup of pitch in strong, black coffee does a great job of removing pitch without harming the blade.