The ABC’s of Overlaminate Selection

When producing pressure-sensitive graphics applications, the proper choice of material components is critical to success. While the initial focus may be on choosing the most appropriate base film for your project, the choice of overlaminate is equally important, especially if graphics will be exposed to extreme environmental conditions. 

There are two reasons to use an overlaminate

(1) to protect the printed graphic from damage, and 

(2) to add aesthetic qualities. 

What do overlaminates do?

In terms of protection, an overlaminate can extend the life of the graphic by shielding it from environmental factors such as abrasion, sunlight, moisture and chemicals. 

In terms of appearance, an overlaminate can add a gloss, matte, textured or other visual finish to the final product to provide added appeal.

There are many overlaminating options to choose from based on your application requirements. The most common overlaminating films include polyester, vinyl, polycarbonate, polypropylene, and fluoropolymers. Specific end-use requirements will dictate which type to use.

Types of Overlaminates

PETs

Polyesters (PETs) can be ideal in terms of providing heat, abrasion and UV resistance. Standard PETs typically provide protection for up to two years, while specialty PETs offer protection for up to five years and can even protect graphics printed with less-durable inks. PETs are especially suitable for automotive and durable applications.

Fluoropolymers

Fluoropolymers offer excellent UV resistance, and some also add graffiti resistance. They are often used for outdoor advertising applications.

Polycarbonate

Polycarbonate overlaminates offer a velvet-textured look, but they can be pricey. Some matte polyesters can offer a similar velvety look without the high price tag. In addition, polyesters can withstand outdoor use, whereas polycarbonates cannot.

Polypropylenes

Polypropylenes (PPs) provide good chemical resistance, particularly to acids, making them a good choice for automotive battery applications. They can be used for personal care applications where some additional protection is desired; however, UV varnish is usually the treatment of choice. Surfaces that may see a lot of abrasion, such as tabletop promotional graphics, may also be good candidates for PP overlaminates.

Vinyl overlaminates

Vinyl overlaminates are prized for their flexibility, especially when used over another vinyl film. Cast vinyls are generally very conformable and will adhere to compound curves while offering up to seven years of outdoor protection, making them an ideal choice for premium life end-use applications such as vehicle wraps and architectural applications. 

Calendered vinyls, on the other hand, offer up to two years of outdoor protection and are ideal for applications on flat surfaces and with simple curves.

Application Requirements: Assessing Your Needs

To select the most appropriate overlaminate for your application, you’ll need to know the application requirements. This will enable you and your materials supplier to determine (a) if an overlaminate is needed and (b) which overlaminate will work best for your application.

Protection

• Duration could range from months to years. The requirements for a shampoo label, for instance, will be less demanding than an extended outdoor advertising campaign or an outdoor power equipment warning label. Therefore, it’s essential to know the expected life of the product or promotion for which you will be printing.
• Exposures such as sunlight, moisture, chemicals, and abrasion can cause graphics to fade, get scratched or otherwise become illegible.
  • Moisture is one of the most common exposures to which graphics may be subjected. Personal care items get exposed to bathroom humidity, beverages get sunk into coolers full of ice, and outdoor applications see rain, sleet, ice and snow.
  • Chemical exposure Caustic chemicals such as motor oil and gasoline are big offenders and can result in graphics becoming illegible and/or falling off.
  • Abrasion can occur during product manufacturing, shipping and daily use. Personal care labels may be repeatedly handled and squeezed, while power tools may get thrown into toolboxes and otherwise banged around and/or exposed to dirt and other abrasives.
  • UV Rays can cause inks to fade, rendering an application illegible or unsightly. 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. Some adhesives will yellow over time when exposed to UV rays, so this must also be taken into consideration for outdoor applications.
  • Temperature Extremes such as the extreme heat under the hood of a vehicle, or extreme cold such as that subjected to cryogenic labels can damage graphics.
  • Weather Conditions may also be a factor, including moisture, extreme temperatures and temperature fluctuations.
• Regulatory requirements such as UL/cUL, CSA and others may narrow your overlaminate options because the materials will need to be qualified. There are many options for pre-qualified materials available on the market.

It’s likely that your application could be exposed to more than one of the above conditions. For example, a lawn mower label will see inclement weather, sunlight, heat and caustic chemicals, so your choice of overlaminate must be able to withstand all those conditions to adequately protect the label. 

A personal care label, on the other hand, may face fluctuations in temperature and humidity, exposure to product contents, and constant handling and squeezing by the consumer. In some cases, a UV varnish may be sufficient to protect the printed graphic, while for more challenging applications, a well-chosen overlaminate could be the difference between application success and failure.

Visual Aesthetics

Although overlaminates are best known for their protective qualities, they can also be used to enhance the graphic in ways that neither films nor inks can accomplish on their own, resulting in visually stunning characteristics that can take a graphic from adequate to outstanding. 

Options range from clear gloss for a shiny appearance, to clear matte for a more subdued appearance, to frosty clear or textured for unique visual appeal. There are also metallic, holographic, satin and soft touch options on the market for brand owners looking to enhance visual and tactile appeal on the shelf.

Adhesive Wet-Out and Release Liner Smoothness

Adhesive and liner choice will impact clarity based on the wet-out characteristics of the adhesive and the smoothness of the liner. Polyester liners provide a glass-smooth adhesive result, resulting in exceptional clarity when adhered to the underlying graphic. Wet-out with a clay-coated paper liner will be somewhat less smooth, and wet-out with a plain paper liner will be the least smooth.

Not all graphics require super-smooth adhesive wet out, however. Images that will be viewed from a distance such as a billboard or building graphic, for example, may look fine with the use of a paper liner, while a brand identification label which will be viewed up close may require smoother wet out to achieve the desired graphic quality. If the inks tend to be raised as with UV inkjet and screen printing, an adhesive with good wet-out will conform to the peaks and valleys of the printed graphic to avoid haloing around the ink edges.

The content of the graphics is another factor to be considered. While most overlaminates can be coupled with clear or white print media, good adhesive wet-out is critical for dark colored or metallic base substrates and inks. While the imperfections created by an overlaminate on a paper or clay-coated liner may not be noticeable on a light-colored film or graphic, those same imperfections will be highlighted over a dark surface. An overlaminate backed with a polyester liner can help minimize these concerns.

Compatibility

Although not a hard and fast rule, it’s generally advisable to pair like films together – vinyl with vinyl, polyester with polyester. This helps to ensure that they will expand and contract at similar rates and have similar levels of flexibility, reducing the likelihood of the overlaminate lifting and separating from the base film. 

Like films will also share comparable durability and resistance to temperature extremes and chemicals. The adhesive on the overlaminate must also be compatible with printing inks. Otherwise, the overlaminate may lift from the printed graphic underneath. Finally, if additional information will be variable-printed post-overlamination, such as via thermal transfer, then the overlaminating film must also be print-receptive.

Work With a Proven Leader

With so many options, variables and potential questions, it’s vital to partner with a supplier who has both the range of products and technical knowledge to help you select the most appropriate overlaminate for your application. It could mean the difference between application success or failure. 

Contact Flexcon to help you make the best decision.