Layflat refers to the film tube after it has cooled, passed through the collapsing frame, and been pressed flat by the nip rollers at the top of a blown film tower. Because the tube is folded flat rather than cut open, layflat film is technically two layers of film with a fold on each edge, and its width is measured straight across as a single flat dimension rather than as a circumference. A 40 inch layflat width, for example, represents a tube that was roughly 80 inches in circumference before being flattened.
Layflat is often the finished form for products like garbage bags, liners, and some shrink film, where the tube shape and folded edges are exactly what the application needs. For other products, the layflat tube is slit along one or both folded edges to open it into a flat single-layer sheet, which is how most flat rollstock destined for bag-making or lamination is produced.
Layflat width and gauge are two of the most frequently specified numbers on a packaging buyer's purchase order, since together they define how much film is on a roll and how it will perform when opened up for use, whether that's as a tube for bag conversion or slit and unfolded for sheeting.
Glossary
Layflat
The flattened, double-layer ribbon of film created when a blown film bubble is collapsed and pulled through nip rollers, measured as a single width dimension.
Example
A spec sheet calling for 24 inch layflat, 3 mil gauge LDPE tells the converter exactly how wide the flattened tube is and how thick each wall of film should be before it gets slit, printed, or made into bags.
Nuance
Buyers new to film sometimes confuse layflat width with the finished open width of a sheet. If a 30 inch layflat tube is slit on both folds and opened flat, the resulting single-layer sheet is roughly 60 inches wide, not 30, so it's important to clarify whether a spec refers to layflat or finished open width before ordering.