There are many types of laminating films with adhesives that range from pressure-sensitive (cold) to heat-activated (thermal) and base films made up of PVC vinyl, polyester (PET), polypropylene (OPP), polycarbonate, and others.
Liquid laminating systems also come in many varieties. Some liquids, such as aqueous and solvent coatings, are cured using ambient, forced air and/or sometimes infrared heaters, while UV curable coatings need UV lamps to cure (harden) the liquid.
When we consider the many reasons for lamination, it becomes clear that the answer to "film or liquid" is not so simple. We over-laminate an image, print, photo, poster, banner, brochure, book cover, for several reasons:
Protect and preserve:
- Prolong the life of image to be laminated.
- Protect the image from fingerprints, smudges, pollution, graffiti.
- Protect the "message" on printed post cards from the mail system's sorters
- Protect bus wraps from weekly "car" washes.
Enhance and beautify:
- To enhance the image by making the surface more uniform.
- To increase the gloss or matte level, or add a special texture (linen, leather, canvas).
Handling and functionality:
- Add rigidity for ease of handling: for example, graphics for pop-up booth or roll-ups.
- Add a slip resistant over-laminate to a floor graphic.
- Add a laminate with a dry erase surface for menu boards.
- Add a coating to make a non printable surface printable
- Required for the warranty.
- Build customer loyalty with a special finish.
Because traditional film lamination is more established, this article will focus on a number of applications where liquid lamination is the method of choice or at least deserves serious consideration.
Laminating Output from UV Flatbed Printers
Most people that have purchased a flatbed UV printer do not plan to laminate their materials. Cutting out the media cost is usually the primary reason for purchasing the printer in the first place.
However, UV Liquid lamination is a very cost effective ($0.01-$0.04 sqft) way to not only protect an image from abrasion, but also to make the finish of the printed board more uniform. This eliminates the banding caused by the direction of the printer heads and adds a high gloss or other finish. There are also specialty coatings the UV liquid coater can apply. There are Anti-Graffiti clear coats, primer coatings for better ink adherence, and a white primer coating that can be applied to avoid having the UV printer print large areas of white.
New to the industry are UV coaters that can do both sheets as well as roll-to-roll coating.
Cost of a UV Coater, depending on the width required and options, ranges from $75K (60 inches/1.55m) to $95K (80 inches/2 m)
Film laminates are a less desirable choice for UV flatbed output because they are significantly more expensive than liquid laminates when compared on a square foot basis. Also, not all film laminates bond well to UV output and the rigidity that the films add is often not needed. Plus there's the waste and trimming factors that are no longer issues to contend with.
Recommendation: UV Liquid Coating
Laminating Brochures, Menus, Fliers, Postcards, Invitations, etc.
These types of prints were traditionally laminated using thermal laminating films (Polyester or OPP film with copolymer adhesive). Small but fast UV coaters are giving thermal laminators a real run for their money. The ease of operation of a UV coater (no need to trim) and the low cost of the UV liquid have made this a real contender for many people operating an HP Indigo, Xerox DocuColor, Canon Image Press, Konica Minolta, Ryobi 4, Heidelberg, and similar digital presses.
If adding rigidity to the image is a major consideration, then thermal film would be a better option as it is available from 1.2 mil (30 micron) all the way to 15mil (375 micron).
Recommendation: UV Liquid Coating, provided that adding thickness/rigidity is not a major consideration.
Laminating Photos for Photo Books
Photo books have become very poplar in recent years. While many photos are finished using film laminates which are available in a variety of smooth finishes such as Gloss, Luster, Satin, as well as textured finishes such as linen, canvas and leather. Liquid laminates are becoming increasingly popular, especially among the mid to high volume producers. Liquid laminates are much faster, less labor intensive, less expensive and in some cases can also add texture to the images.
Cost of a small-format UV liquid coater with texturing capabilities can range from $29K for a 17-inch (43cm) model up to $57K for 36-inch wide (91.4cm) models.
Recommendation: UV liquid coater for mid to high volume producers.
Laminating Canvas (Giclee/Fine Art) Inkjet Prints
Laminating Giclee and other high end inkjet output on canvas and other media can be done by either a liquid or film. While very good results can be achieved by film laminates, many artists still tend to favor a (aqueous or solvent based) liquid as they are more comfortable applying a liquid spray or rolled on coating than a "plastic". Both film overlaminates and liquids can provide UV protection required when fortified with the proper UV absorbers and light stabilizers.
Typical water based (aqueous) coatings, depending on the application range in cost from two to 26 cents per square foot. Aqueous liquid sheet fed coaters cost between $5,000 for a 17-inch-wide (43cm) model and $8,000 for a 24-inch-wide model. A 60 inch (152cm) roll-to-roll aqueous liquid coater costs approximately $16,000.
Recommendation: Aqueous liquid coating or overlaminating film.
Laminating Soft Truck Sides
While soft truck sides are not as popular in North America as they are in Europe, the application is growing in popularity. Protecting heavy duty PVC Vinyl graphics up to 10 feet (three meter) wide is normally done with aqueous UV liquids, primarily due to their long term outdoor durability characteristics, generally as part of a warranty system. Film overlaminates are unavailable wider than 96 inches (two meters), are often too costly and not flexible enough for the rigors of constant rolling and unrolling.
Aqueous liquid coaters cost approximately $20,000 for a model 75 inches (190cm) wide and $35,000 for one 128 inches (3.25m) wide.
Recommendation: Aqueous liquid coating
Laminating Vehicle Wrap Graphics
Most vehicle graphics printed on vinyl are protected with either a cast/calendared PVC vinyl film or liquid laminate. Film laminates are preferred by some because the additional thickness a film provides may make installation easier. Others prefer liquid because of the lower cost and its conformability. The option of a liquid coating onto some of the thinner calendared vinyl (3.5 mil) is now gaining popularity due to its lower cost and ease of application. Many companies now offer long term outdoor warranties using a combination of cast/calendared materials and liquid laminates
Aqueous liquid coaters can range from $16,000 for a model 60 inches (152cm) wide to $20,000 for one that is 75 inches (190cm) wide.
Recommendation: Film overlaminate or aqueous liquid coating. UV coating may be an option soon as the first wide-format roll-to-roll UV coaters are hitting the market now and warranties are expected to follow soon.
Lamination Wall Graphics
Most digital printed wall graphics are protected using liquid laminates because it is difficult to achieve both conformability to heavy textured wallpapers and flame retardancy as is often required for most films.
Recommendation: Aqueous or UV liquid coating.
This list is by no means comprehensive; there are many factors that need to be taken into consideration when deciding on the most appropriate finishing system for your application. Check with your vendor for specific recommendations.