Transtar’s Mul-TIE Adhesion Promoter greatly enhances the adhesion, appearance and durability of virtually all types of automotive finishes including problem plastics, such as TPO and polypropylene. Mul-TIE can be used under primers on flexible and rigid plastic parts, as a tie-coat between fresh or existing primer and color (single stage or basecoat) and for painting aluminum or steel. TDS 101.