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Matching the Materials to the Job: Part I
Most of us are aware of the fact that lamination can protect our prints from moisture, fading, air pollution, graffiti, etc., and that lamination can make dull flat colors appear more vivid. What you may not be aware of, however, is how many different laminates are available and the differences between them.
Let's face it, many reprographers have at one time or another found themselves face-to-face with an important job that took a while to RIP and print, only to have it die an untimely death at the finishing station. This costs you time and money (not to mention hair).
I am also sure that most of you have since found a tried and true method and/or list of materials that works for you. While these methods may seem to get the job done, they may actually have caused you to inadvertently limit what you can or cannot do in your finishing department. Some of you may even be turning away work or farming some jobs out due to previous nightmarish experiences.
The purpose of this article is to shed some light upon what types of overlaminate films are available, and which products are most appropriate for your application. A good number of people today perceive mounting and laminating as a necessary evil like doing laundry. I would like to take this opportunity to dispel that myth. If the correct combination of media, ink, substrates and laminates are used, your laminator can become one of the greatest profit centers available to your business.
What must be remembered is that not all jobs can or should be laminated with 3-mil polyester gloss on the front and 3-mil polyester gloss on the back. Many customers are becoming more aware of what is available to them, and they are less likely to accept the bare minimum. Knowing this and knowing what different types of laminates are presently available, and the pros and cons of each, will get you well on your way to the finishing finish line.
What Is Available?
Laminates basically fall into one of the following five categories: pressure-sensitive films, standard thermal laminating films, low-temperature thermal laminating films, HeatSet™ (or heat-assisted) laminating films, and liquid laminates.
Different Types of Laminates
Standard Thermal Laminating Films
Low-Temperature Thermal Laminating Films
HeatSet (or Heat-Assisted) Laminating Films
These laminates all have different properties that can make them more appropriate for some applications than for others. The fact that many laminates may not necessarily be compatible with your preferred media or substrate is very important to know, and knowing which ones these are, will make your life a lot easier not to mention less expensive.
Most people are aware of the fact that you should always test a new laminate with the substrate (vinyl, paper or board) and inks that you intend to use with your printer. This has been reiterated in virtually every article that I have seen covering the subject. Though I’m sure you don’t want to hear it, I’m going to tell you: test, test and test again!
What some people are not aware of is the fact that something so seemingly trivial as changing the inks on your printer can have an adverse effect when attempting to laminate a print. If any of your variables change (and not just your laminates), the results could spell disaster for a print when laminated -- even prints you have had no previous problems with. Remember that it is not only your laminating film that will affect the outcome when laminating.
Always remember that there are many different factors that come into play when deciding which type of overlaminate you should be using, of particular note are the following: type of print media being laminated, substrate, inks, type of laminator, and final destination for the finished print.
Depending upon the type of laminator you have, your choices can range from severely limited to limitless. For example, if you only have a cold-roll laminator, then you can only use pressure-sensitive laminates. If you have a hot-shoe laminator, using pressure-sensitive or heatset materials can vary from very difficult to use to impossible. If, however, you have a multi-heat laminator (MHL) "roller laminator," then you can use almost any of the following five categories of laminates. The exception, of course, is liquid laminates, which require a completely separate machine operating on different principles altogether.
The following is an analysis of the pros and cons of each variety of laminate, and when their use is deemed most appropriate.
Pressure-Sensitive "Cold" Laminates
If you are going to be applying a laminate to heat-sensitive material, then pressure-sensitive laminates are one of two types that are perfectly suited for the job.
As many of you are aware, pressure-sensitive laminates, while being the most versatile (they can be used with virtually any substrate), are also the most expensive type of laminates available. Do not allow the price factor to dissuade you from using them, however, because they are also the most reliable. One of the reasons they are so reliable is because they are, as the name suggests, applied cold. Hence, there is little problem with ink separating from the paper, or having your inks boil off of your media. This is of particular importance for applications where a coated ink jet paper is being used. Another thing going for pressure-sensitive laminates is that they can also be purchased with specialty and textured finishes, including write-on/wipe-off, and frosted Lexan-like finishes, ideal for trade show graphics, floor graphics, etc.
The most common pressure-sensitive laminates are made up of PVC (vinyl), but there are also pressure-sensitive laminates that are polyester, polycarbonate, and even Tedlar. These films are coated with a pressure-sensitive adhesive that provides bond to virtually any output. Not only does the adhesive bond with the surface of the print, but it also bonds directly through the surface inks into the paper itself.
The vast majority of older model hot-shoe laminators are not compatible for use with pressure-sensitive laminates. This is because these laminators use a spring-loaded mechanism with which they apply pressure. Unfortunately, they do not apply enough pressure for pressure-sensitive laminates to bond effectively and have no apparatus with which to increase the pressure. Only some of the newer models of hot-shoe laminators provide enough pressure to make them suitable for the application of pressure-sensitive materials.
Most roller laminators have been designed so that the application of pressure-sensitive materials is not a problem, and is in fact fairly straightforward. Most importantly, before purchasing these materials, ensure that your machine has a "take-up" mechanism for release liners. A release liner that protects the adhesive on the laminate accompanies all pressure-sensitive laminates.
Perhaps the greatest drawback that one faces using this material is its price. Pressure-sensitive materials are, without question, the most expensive type of overlaminates available. They are almost 4 to 5 times more expensive than standard thermal 3-mil gloss.
You may come across a chemical reaction between ink jet inks and the adhesive of the laminate. These reactions, however, are extremely rare and are limited to the inks of a few select ink jet printers, the majority of which are no longer in production.
We will continue examining the pros and cons of various laminates in Part II of Matching the Materials to the Job.
Hayden Kelley is the General Manager of Drytac Canada Inc. Drytac is a manufacturer and distributor of mounting, laminating and finishing materials and equipment, as well as installation & finishing accessories. Phone: US 800-280-6013 Canada 800-353-2883 or e-mail firstname.lastname@example.org. For more information, visit www.drytac.com.
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