Threaded cup brush with twisted stainless steel Instructions Manufacturers shall provide mounting and safety instructions as follows. a) Brushes should not be mounted on machines having a speed in excess of maximum permissible brush speed. b) Damaged brushes should not be used. c) Rust discoloration or other signs of chemical or mechanical changes of the fill material may cause premature failure. d) Brushes should be stored in suitable racks, containers or boxes in such a manner that they are protected against the effects of: 1) high humidity, heat, water or other liquids which might cause damage to the brush; 2) exposure to acids, or fumes from acids, which might induce deterioration; 3) any temperature low enough to cause condensation on the brush when removed from storage to an area of higher temperature; 4) distortion of any of the brush components.