The most expensive coating is also the most reliable. Film lamination can be applied wet and then dried or pretreated with an adhesive that releases under heat and pressure to bond to the cover (thermal lamination). Traditionally, the wet application was considered appropriate for “long run” applications and thermal was considered more suited for “short runs”. Technology has blurred this distinction on modern applicators.
The first films were glossy. The least expensive was polypropylene (POP). It provided good protection and wonderful gloss. Unfortunately, when the humidity and temperature changed, the covers had a tendency to curl up. Many publishers changed their cover paper from 10 pt. c1s to a heavier sheet, generally 12 pt. c1s, to try to eliminate the curl.
Some printers switched from the POP to polyester, a pricier film that offered better protection and seemed to minimize the curl.
Eventually, a nylon curl free laminate was developed. It was offered as gloss or matte and in a number of finishes and embossings. Film can even be overprinted with a dull spot varnish applied to a glossy film to accentuate an image, a color, or a type.
And film lam is still being improved today. In 2007 alone, a new matte film has been introduced to eliminate the little hairline scratches that the dull finish could show. A new BioLam film lam has been introduced which is antimicrobial to kill germs on contact (according to the manufacturer anyway).
Film lamination is not only the best cover protection today; it also offers more opportunities to the designer than any other coating.
Improved coatings have done more to stem the tide of bookstore returns than any other product or manufacturing adjustment.