Our Vacuum Bag Film is a clear, heat-stabilized, modified nylon resin film. Can be used at temperatures up to 350°F (176°C) for typical composite cure cycle times. A tough, stretchable film for high vacuum pressures.882-20 Vacuum Bag Film, 60″ wide x 20 yd roll
Why vacuum bag a laminate?
The process of vacuum bagging allows for the ease of hand lamination while producing a part that has better properties because of its compaction. Vacuum bagging a laminate removes air voids and increases the fiber-to-epoxy ratio. All in all, it is a great process to improve your composite laminate.
The top layer of a vacuum bag laminate is created with our plastic Vacuum Bag Film. Seal it to the mold with with Vacuum Bag Sealant so a vacuum can be pulled. This layer will need to be cut over-sized to accommodate for curvature in the part. The diagram below shows all of the layers in a vacuum bagged laminate.
Pleating vacuum bag film
Where there is a corner or bend in the part, put a pleat in the bag. This is a fold that sticks up and allows the vacuum bag to move and conform nicely to the part under vacuum.
Without pleats, you may get bridging or cause a tear in the bag. Bridging occurs when the bag does not fold down completely on an edge and makes the edge more rounded (it will look like a filleted edge). This fillet area will not be compressed by the vacuum pressure. If there is no pleat on a corner, it may poke a hole through the bag and cause it to rip depending on how much force is on that spot.
When laying down the bag on your laminate you will also have to take into consideration where to position your vacuum port on the bag. The hole for the vacuum port should be small and easy to seal well so no air will leak into the assembly.
—Excerpted from Vacuum Bagging Basics by Rachael Geerts in Epoxyworks 49.