A headliner is a composite material that consists of a face fabric with nonwoven
or foam backing that is adhered to the inside roof of automobiles. Most headliners consists of a [tricot]
knit fabric that is knapped to provide a soft touch and uniform appearance. The fabric is adhered with melted polyurethane foam. This fabric-foam composite is glued to the interior fiberglass roof of the automobile.
Less Common Headliners
There are more complex knit products used as a face fabric, as well as less expensive non-woven products. There are headliner developments that include environmentally friendly products made of recyclable backing-adhesive and face fabric.
When a headliner fails, it sags or falls from the roof. Many repairs involve tacking or replacing the entire headliner. Heat, humidity and time rapidly degrade the bond that the polyurethane foam has on the face fabric. As the foam oxidizes and yellows the fabric-foam bond falls. This failure is more common in cars produced in the 1970s.