Definition
A thin sheet of plastic film placed between a curing composite repair or layup and the surrounding tooling, bagging, or bleeder material to prevent the resin from bonding to anything other than the part itself. Some release films are solid (non-perforated) to block resin flow entirely; others are perforated to allow controlled bleed-off of excess resin and air during cure.
Plain English
A non-stick plastic sheet used during composite repairs so the wet resin doesn't glue itself to the tools, bag, or padding stacked on top of it.
Context Anchor
Seen during aircraft composite and fiberglass repairs, especially when the repair is covered, pressed down, and allowed to cure.
Derivation
Called 'release' because its job is to let everything release cleanly from the cured part once the resin sets. The film 'releases' rather than sticks.
Why Pilots Care
Ensures clean separation after curing so the composite part and tooling remain undamaged and structurally sound.
Analogy
Like the parchment paper a baker puts under cookies so the dough doesn't stick to the tray.
Intuition Check
Release film is not a movie film or a document that authorizes a repair. Here, film means a very thin sheet, and release means it lets other materials separate cleanly after curing.
Example Sentence 1
The technician laid release film over the wet layup before placing the bleeder cloth and vacuum bag.
Example Sentence 2
After the resin cured, the release film peeled away without leaving residue on the repaired wing surface.