JAIKAY Phosphor Bronze Doctor Blade

phosphor bronze is an alloy of copper and tin. it conducts heat readily and retains a sharp cutting edge. its hardness (normally measured on the brinell scale, but converted to the rockwell c scale for comparison purposes) is about 16 rockwell c. bronze is generally regarded not as a sheet removal blade, but more as a conditioning blade for new or reground metal rolls. the exposed surface of new and reground rolls is usually quite porous and does not release the sheet cleanly. bronze is an excellent sheet release agent, and will readily transfer itself into the pores of a steel roll to give a smooth surface which will offer good paper making qualities.
it is therefore normal practice to run bronze blades on new (or reground) rolls for 15 to 60 minutes at crawl speed to develop this conditioned surface. if the dryer cylinder was reground within the last year or so and a bronze blade was not used to seal the surface, it can still be done with a good result.