the manufactures of your cars must have though undercoating was the answer to any problems as they use a lot of it. after 60 years it's not in good shape dried out and falling down causing more problems they it stops. but how to remove it. I have tried a lot of ways bit I saw a needle scalier in the harbor fright store. we tried it and it works but the tool was not the best . so we got one that would screw onto the air hammer. it does the trick. removes it fast and fairly cleanly. I though when I left the Navy I would never use another one of these again but here I am buying one. I don't think you want to try this on your 2000 and up cars though. we did half the hood. bothe front fenders and the rear wheel wells this afternoon. glad to have that chore done. when I lost that set of Micky mouse ears in my sea bag I did think I would use them for this.