new shoe`s are soft and will get a harder surface with the heat from the slip it has. its called running in the shoe. When run in the shoe will last longer.
What i do to all my clutch shoe`s is, i do the running in in the oven.
Bake them in a hot air oven for 20min on 200degrees Celsius.
Never had a problem with clutch shoe dusting. Shoe lasts a whole year.
Use 0.7 to 0.9 gap with hard clutch spring.
Maybe helpful to try one.
Have fun.