First of all, if your formulation contains graphite, mix with antimony trisulphide 100mesh in equal proportions and then add in the mix as per their procedure. Generally , they require 325 mesh for uniform mixing only. The Material character will not change. It changes based on the purity of the ingredients. Ask them to mix with graphite. Increase the mixing time' 1minute as additional in overall mix.you can well use 100 mesh.