I had a set on for about 3-4 months, when a bubble wouldn't go away. He sent me out a new set for free, and when I removed the old grips, all there was to clean off, was a dirt line around where the grips were. You wipe the grip off with alcohol first anyway to put the grips on. That was enough to clean off the old grips. Wont harm your gun at all, and they've endured scratches that my glock would have got directly. Best $10 you'll spend on your glock next to ammo.