What is the end-use application?
It is essential to understand every aspect of the end-use application before an overlaminate can be suggested. Where is the application going to be used? What conditions might it face? How long will the application need to survive, and what constitutes success in this regard? An overlaminate that might work well for a three-month floor graphic promotion may not be sufficient for a two-year outdoor advertising campaign.
At the same time, such questions allow an experienced supplier to offer the right balance of cost and performance. Although it is vital to provide a product that meets all specifications, an over-engineered product can lead to unnecessary expense. That is why it is crucial to work with a trusted supplier who can offer a wide array of standard and custom products, but who will also not sell you a product you do not need.
What type of substrate are you overlaminating?
Just as you must match the right adhesive/liner combination to an overlaminate, so, too, must you pair the right overlaminate to a specific substrate. The “sandwich” (film, topcoat, adhesive, and liner) only works when all of the individual components work together. Thus, nothing can be designed in a vacuum. An overlaminate that may be ideal when paired with a vinyl film may work with a polyester substrate, or it may not. Again, the end use of the application may also need to be taken into account.
Special consideration should be given when identifying possible overlaminating limitations. For example, using a polyester overlaminate with a paper substrate could result in problems. A similar issue could arise if a polyester overlaminate were used with a vinyl substrate. Ideally, you should use an overlaminating film that corresponds with the substrate film. For example, if you are using a polyester substrate, a polyester overlaminate would usually be preferable. This is partly because the use of similar films ensures that they expand and contract at similar rates, reducing the likelihood of the overlaminate lifting and separating from the base film.
What type of environment will the end-use application be subjected to?
Will the application be indoors or outdoors? Does the ambient temperature remain consistent, or does it fluctuate between extremes? Must the overlaminate protect against wind, rain, snow, and UV light, or will it face the grueling conditions of the under-the-hood environment? Different overlaminates are better suited for different situations.
Indoor applications such as personal care labels are typically UV varnished versus overlaminated. A varnish is much more cost-effective as the product is typically disposed of in three to six months.
For outdoor applications, the overlaminate must protect graphics from temperature fluctuations, abrasion, chemicals, and exposure to UV light, as well as the wear and tear associated with regular use. The overlaminate must, in this example, also utilize a UV-resistant pressure-sensitive adhesive. Overlaminates used to resist UV exposure may have UV absorbing additives formulated into the film, or may have an adhesive with a UV-absorbing additive, or both. In short, the printer needs to be fully aware of the end-use application and the environmental conditions the product will face so that he can work with a supplier to find an overlaminate that will fully protect the application.
What are your durability requirements?
Similar to the question of environmental exposure, durability touches on the endurance requirements. Must the application remain legible for the lifetime of the product? If so, what is that lifetime? If you are creating a personal care label, the product may face the humidity of the bathroom environment and require non-slip characteristics, all while remaining graphically appealing. In such cases, the product may only be expected to last a few months. This stands in contrast to a piece of outdoor equipment, whose safety labeling may be expected to remain legible for years.
A good example would be a safety and hazard warning label used in conjunction with outdoor power equipment, such as a lawnmower. Here, the overlaminate must protect the graphic from exposure to oil, gasoline, UV light, and moisture, as well as the wear and tear associated with regular use. As previously noted, the overlaminate must, in this example, also utilize a UV-resistant pressure-sensitive adhesive.
Personal care labels are typically UV varnished versus overlaminated. These products may face a host of potentially damaging environmental conditions, such as fluctuations in temperature and humidity, exposure to product contents, and constant handling and squeezing by the consumer.
What printing technology will be used?
Different printing technologies are associated with different levels of rigor. Flexo and HP Indigo may not withstand challenging environments without the use of a durable overlaminate. Another consideration is the potential use of variable imaging. If there is an expectation that the end user will use variable imaging, the overlaminate will need to be receptive to that particular print technology.
Overlaminates can help counter this issue by providing a protective layer that seals the graphic against abrasion, helping to ensure that physical contact will not wear the image or text away. Thus, overlaminates can be a defensive barrier that protects the application from catastrophic failure.