Vacuum bagging

The flexible, airtight polymer film that forms the outer membrane of a vacuum bag, sealed to the tool with sealant tape. Films are selected for cure temperature capability, elongation and puncture resistance, and pleats are added so the film can conform to the part without bridging.

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.

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 tacky butyl rubber tape used to seal the vacuum bag film to the tool flange, or to itself, forming an airtight envelope around the laminate. Grades are chosen to match the cure temperature and to release cleanly from tooling afterwards.

Intermediate vacuum compaction of a partially completed prepreg stack, carried out periodically during lay-up to remove trapped air and seat the plies before further layers are added. Regular debulks reduce wrinkling, bridging and final void content, especially on curved tooling.