9. After the door frame fasteners are locked, do anti-rust treatment, use a brush and then paint the surface of the self-tapping nails with black paint
9. The door frame fasteners shall be treated with rust prevention after locking, and the surface of self tapping screws shall be painted with black paint with a brush
9. After the door frame fastener is locked, antirust treatment shall be carried out, and then black paint shall be applied to the surface of the self-tapping nail with a brush.