Release film is used between the laminate and the breather fabric. Release films are available either non-perforated or in a wide range of perforation patterns, usually described by a "P" designation. The patterns are outlined in the list below:
P .045” diameter holes, staggered on ¼” centers.
P1 .045” diameter holes on ½” centers.
P2 Small slashes on ½” centers.
P3 .015” diameter holes on ¼” centers.
P4 .045” diameter holes on 2” centers.
P5 .045” diameter holes on 3 ½” centers.
P6 .015” diameter holes on 2” centers.
P3/7 .015” diameter holes on 3 ½” x 7” centers.
P8 .015” diameter holes on 8” centers.
P11 .015” diameter holes on 1/8” centers.
P31 .015” diameter holes on 1” centers.
P34 .045” diameter holes on 3/4” centers.
Most wet-laid vacuum bagging operations are done with a P3 film, while prepregs are laid up with non-perforated film. This P6 film is less permeable, bleeding less resin from the layup while still allowing air to be efficiently pulled from the laminate stack, which may be useful in certain prepreg layups. Generally the perforation style is chosen based on resin and/or prepreg manufacturer specifications.
ETFE films are capable of handling process temperatures up to 450 degrees Fahrenheit.