Is it really PV or acrylic or Poly Cotton? Who was the maker?

If it is a USA Kilts (or any MM PV Fabric), then there's no need to brush it. When dirty, just pop it in the wash on cold with like colors. DO NOT use fabric softener. When it's done washing, lay it flat to dry. Be sure to "neaten" up the pleats while it's wet (straighten out each one and make sure the edge of the pleat it crisp). This will make it easier to iron when dry.