I don't often do sequels (I will consider requests), but I was just getting started last month when I wrote about finishing methods that protect printed materials while adding gloss. This month, I'll pick up where I left off (varnishes and coatings) and look at film lamination.

Nothing beats this method in terms of the durability, high gloss and scuff-resistance it imparts to the finished product. That's why it's everywhere: menus, cards, placemats, pocket calendars, outdoor posters, book covers, dust jackets, video slipcovers, cassettes, index tabs, maps and packaging. Another popular application is write-on/wipe-off wall posters. Lamination is also appropriate for presentation folders, binders, brochures, and casebound products.

The Basics. Lamination involves the bonding of a thin, transparent film, typically polypropylene, polyester, acetate or nylon, to the surface of the press sheet or other substrate. The film is applied in one of two ways, either via the wet method or the thermal method. The wet method is the more complicated of the two and involves the use of solvents or water. The finisher applies the adhesive to the film as the film is being applied to the substrate. This method tends to be less expensive than thermal but there may be environmental problems with the drying of the glue. The thermal method, which has become popular in the last few years, uses 250 to 300-degree heat to meld film and substrate. The type of film used is pre-coated with polyethylene adhesive and is more expensive than film without adhesive. Today, the dominant process is thermal, so I'll focus on this process.

One drawback of the thermal method is that the heat involved causes polyester and polypropylene films to stretch while being applied, and this sometimes causes curling of the finished piece. To avoid this problem, specify layflat nylon film (also known as curl-free). Nylon film is generally more expensive than other types. Of all the films, however, it's the most stable. Currently, it's available in a clear (gloss) finish only, film manufacturers are working on a matte version.

The most popular film is polypropylene. It comes in a gloss or matte finish and is the least expensive. Polyester film, which comes in gloss or satin (not a true matte), has a harder finish and is a little more resistant to scuffing and tearing than polypropylene. Acetate film is the least used because it's more brittle than other films and has a tendency to tear and scratch.

All films are classified by thickness, which is measured in mils (increments of 1/1,000th of an inch). The thinnest film, about 1.3 mils, is good for products that will be rolled or folded, such as menus, maps, book covers, book jackets, etc. Heavier films, 3, 5 and 10 mils, are used for menus, credit and ID cards, and posters. You wouldn't want to coat a brochure in 10 mil-film, it would be a real struggle to fold it. A good medium-weight film is 5 mils; it's half as expensive as 10 mils and gives products a stiff, substantial finish. By combining 5 mil-film with a heavier paper stock, it's possible to achieve, at a significantly lower price, results identical to 10-mil lamination. Usually the heavier films are applied to both sides of the substrate, while the lighter films are often applied to one or both sides. Often, films above 3 mils are extended over the substrate's edge to create a seal, this makes the piece waterproof.

Lamination Specs. Fortunately, films are pretty easy-going and will adhere to virtually any paper or cardstock, as well as to cardboard and cloth. Heavy paper stocks are better than lightweight, which tend to curl when laminated. Occasionally, films will have trouble sticking to uncoated or heavily-textured stocks, such as Gainesboro, because it's tough for the film to get down into the valleys of the paper. If you're concerned about the compatibility of your stock with lamination, have your finisher do a test run.

As with coatings, lamination yields the best results when used over wax-free inks and varnishes. If some wax is present in your ink or varnish, ask your finisher to run a test sheet. Your finisher may recommend the wet method of lamination, which will permit the use of a very aggressive adhesive to effectively bond the film to the substrate.

Factors to consider in choosing lamination versus varnishes or coatings are end-use, cost and other finishing processes involved in the job. Since lamination is the ultimate in terms of gloss and structural strength, it's an excellent choice for products that must withstand heavy usage. On the other hand, lamination is uneconomical for products with a short shelf-life, such as menus with prices that will change frequently. While the price of lamination varies according to the type of film used, in general it costs twice as much as UV coating.

Lamination can be done in conjunction with die-cutting, scoring, embossing and debossing, but these processes should be performed after the film is applied to the substrate. If the product is embossed before lamination, the bump-up (height) of the embossed area will be smashed flat by the rollers that apply the film. If the job involves deep embossing, chose a soft film, such as polypropylene, that has greater elasticity than other types. As always, run a test first to make sure your film won't crack under the pressure of embossing.

Most finishers report mixed results when foil-stamping on films. As I noted in an earlier column, foil stamping should be performed before lamination to minimize adhesion problems. An alternative is to use stampable polyester film. The surface of this film is treated to accept foil more readily than untreated films.

For projects that will be glued, such as presentation folders, bags and box wraps, specify a glueable film. The cosmetic packaging, toiletries and pharmaceutical industries usually insist on glueable films.

Finally, because of the way film is applied, there's no such thing as spot lamination. If you don't want to cover the whole sheet, spot-coat a varnish or UV coating. Or, film laminate with a matte film and spot-U.V. coat on top of it, it has a great effect!

Time to repeat Marty's Maxim #1: For best results every time, plan lamination into your project at the outset.