This 
              is one of the most difficult properties to check on dies and die 
              inserts. A high gloss finish in itself is not enough. Just looking 
              down a die to see how shiny it is does not constitute a full inspection 
              of the finish. With a poorly polished die all efforts by the header 
              operator are minimized.
            Close 
              examination by a trained die maker or inspector of a cast of the 
              die in question will reveal the level of polish. Any blemishes 
              on the body or angle, or back taper of the body will result in poor 
              die performance.
            The I.D. 
              straightness of the die can be checked with a dial bore gage. This 
              will indicate if there is any transition in the diameter of the 
              part being checked.