recently in order to remove a large bird dropping on the bonnet which was like cement i used one of these small household cleaning sponges with a rough back to it. instead of using the sponge i must have used the rough part in an attempt to remove the hardened remains of the ddropping. i now see the area all scrathed. i have been told that there are waxes which remove ssuch scrathing....are they effective and any advice would be welcomed....i know what to do in the future...hot water and a rag!