Material:

1.    PET /PBT/PET+PBT/PP/nylon filament for paint brushes.

2.    PBT full name is polybutylece terephthalate, if to make brush, mainly for chemical taper process,  Nylon mainly in physical taper

3.    Cross section of one filament from microscope: solid, big hollow, mini hollow, fan shape, x shape, triangle, square shape, star shape ect