[VACList] Removal of grey stuff

[Tombhs@xxxxxxx]

Hello:  Anyone have any experience removing that thick gray stuff that is 
sometimes painted on to the top of older trailers?  Don't know the name of it 
but the people at the local RV place say they either chip it off with a putty 
knife or grind it off with a wire brush.  I hoped some of you scientists out 
there may know of a solvent or some other means of getting this stuff off.  
Tom Fairbank
1969 Tradewind