Laminating is the process of applying a clear film to either one side or both sides of a printed document. A wide variety of digitally printed applications (as well as conventionally printed applications) are laminated.

Applying laminates to print products is usually done as an off-line process and can add a significant cost to the finished product, however it provides numerous benefits. The use of lamination serves several purposes:

• Lamination adds luster or gloss to a printed product.
  
  
• It provides stability to the sheet, allowing it to be more durable or to stand upright.
  
  
• It provides protection to printed products that are handled frequently or may encounter moisture.
  
  
• Many laminated documents are waterproof, tear proof, and tamper proof.

Lamination can be a useful and often necessary addition to various products. Listed below are some of the many digitally printed products that are laminated.

Maps
Signs
Menus
Charts
Covers
Badges
Posters
ID Cards
Calendars
Price Tags
Placemats
Certificates
Food Labels
Photographs
Business Cards
Membership Cards
Point-of-sale Materials

A security badge is the type of
print product that is often laminated.

There are two categories in which all types of laminated products can be classified: products that have been laminated with pouch lamination film and products that have been laminated with roll lamination film.

Pouch Laminates

Pouch lamination films resemble envelopes and are sealed on one edge. The print product is inserted into the pouch and is sealed within. The pouch films come in many standard sizes to accommodate commodity items, such as letterheads or business cards, or they can be produced into any custom size.

Roll Laminates

Roll lamination films consist of a layer of film that is applied to the front side of a document. Roll laminates are also constructed of two film layers to allow a document to be sandwiched between the layers and sealed by the use of various processes.

Many of the films used for laminating are available in various thicknesses and finishes ranging from clear gloss to delustered. The three main film materials used for lamination processes are polyester, polypropylene, and nylon.

Polyester

Polyester is the most widely used material for film laminates and can be used for almost any type of application, but it is most often used for book covers, dust jackets, folders, and video slipcovers. Polyester film is heat resistant, foldable, scuff and scratch resistant, flexible, and tough. Polyester film will not become brittle with age because it contains no plasticizers.

Polypropylene

Polypropylene is the clearest and brightest type of film and it is used for such applications as posters, labels, marketing, materials, and write on/wipe off calendars. It offers chemical resistance and good optical properties.

Nylon

Nylon film is another good choice for applications such as book jackets because of its scratch resistance and excellent non-curling properties. Nylon laminate is a very stable material. When it is exposed to heat, it will not stretch, and when it is cooled, it will not shrink.

Thermal Lamination

Most film laminates consists of two plies. The top ply contains an adhesive on the backside of the film and the bottom ply contains an adhesive on the top of the film. The adhesive is dry and it is not tacky to the touch. The document is placed between the two plies of the laminate film and is sent through equipment that applies heat and pressure. The dry adhesive becomes tacky when it comes in contact with heat source. Pressure is used to press the laminates together (with the document sandwiched between the two plies). After cooling, the adhesive solidifies, which provides a permanent bond between the document and laminate film.

Cold Lamination

Cold lamination is a process in which only one side of a document is laminated. This laminating process is required when the ink and/or paper used for a document cannot withstand the heat required with thermal lamination. The film used for cold lamination is more expensive than the film used for thermal lamination, but the laminating equipment is less expensive.

Dry adhesive is not used for cold lamination as it is for thermal lamination. The surface of a document is flooded with a water-soluble adhesive. The document is then sent through a set of rollers where the laminating film is rolled onto the top of the document and the adhesive. Pressure is applied, which evenly distributes the adhesive and bonds the film to the document. The adhesive takes a bit longer to cure than thermal lamination and lighter stocks can wrinkle or warp because of the water based adhesive. Cold lamination usually is not as permanent as thermal lamination.

• Allow several days for laminated sheets to cure, since the adhesive takes time to fully adhere to the stock.
  
  
• Use caution when applying a lamination film to varnished sheets. Use a varnish that dries quickly, contains minimal residual solvent, and contains no wax additives.
  
  
• Do not laminate documents printed with metallic inks because adhesion problems may occur.
  
  
• Adhesion problems may occur when laminating documents in which a significant quantity of anti-setoff powder was sprayed onto the surface during printing.