Peel ply

The adhesive joining of two or more fully cured composite or metallic parts in a separate operation after moulding. Joint performance depends heavily on surface preparation, adhesive selection and control of bondline thickness.

A thin polymer film, often perforated, placed between the laminate and the breather in a vacuum bag stack. It prevents the breather bonding to the part, while the perforation pattern controls how much resin is allowed to bleed out during cure.

A non-woven synthetic felt placed over the release film inside a vacuum bag to maintain a continuous air path across the whole part, so that vacuum is drawn evenly, and to absorb any resin that bleeds through. It is discarded after cure.