if its tar you can tell straight away - when on the foil it will give off clouds of smoke smelling of vinegre BUT once you burn it off it can be damn fine gear full of 6mam. Im taking a weeks break as i was getting thro an 1/8th inn 4 days. Gear seems to be alwyas the same in terms of strengh , i would say 35-40% or like i posted b4 raw at 10 a point - just wish i could get some decent stones