By Jeff Stadelman, Technical Marketing Manager, MACtac® Graphic Products

Take advantage of the knowledge that lies with those who research, test and manufacture the materials that drive the graphics industry and enhance your ability to recommend solutions to your customers.

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The graphics industry is abundant with films. Films manufactured through casting, calendaring or extrusion processes, films designed for image protection, printing media or simple lettering - the list goes on and on. As manufacturers, printers and installers work to increase their profitability and build their reputations and customer bases, it is important to master the art of working with all film options available. When it comes to film types and recommendations, installers know what has worked for them in the past and what materials they like working with. They look to print shops for more than printing or packaging the final materials and they want you to provide solutions.

Working with an experienced supplier to understand common film types and their associated end uses will help you as a print shop to better determine what makes certain films more viable for one application than another. Take advantage of the knowledge that lies with those who research, test and manufacture the materials that drive the graphics industry and enhance your ability to recommend solutions to your customers.

Keep the End in Mind in the Beginning
The properties that make up film compositions vary from one film type to another. Therefore, it is important to have a clear understanding of the film's intended use because it is what drives film selection. Films are not commodity products. Just because two films have the same thickness and appearance does not mean they will perform the same. Also, price is not generally a good basis for film purchasing decisions. While the cost of a select film might seem appealing up front, it may not meet performance requirements in the end. The cost to correct issues caused by using the wrong film is much higher than the cost of buying the right film initially.

Pressure-Sensitive Films
Pressure-sensitive films can be broken into two broad categories: Base films and over-laminating films. The most common pressure-sensitive film type is polyvinyl chloride (PVC), commonly referred to as "vinyl." PVC is relatively inexpensive, has excellent lay-flat and conformability characteristics and is durable.

Other less frequently used pressure-sensitive films include polycarbonate (PC), polyester (PET) and polypropylene (BOPP). PC is the most expensive pressure-sensitive film and generally is found in higher thickness levels such as 5.0-, 10.0- and 15.0-mils and is used where stiffness and durability are the key variables in the finished graphic. PET offers exceptional clarity and BOPP has a unique quality that provides the finished graphic with a "dry-erase" surface.

Whether the film type is PVC, PC, PET or BOPP, three layers typically comprise pressure-sensitive films: Face stock, adhesive and liner. These three components vary with each solution and no one part is greater than the whole.

The Face Stock
For starters, face stocks may have different finished textures, ranging from a high gloss to a dull matte. The face stock finish alone can determine if a film is suitable for an application. Not only is face stock selection reliant on the specifics of the application (e.g., environmental conditions, intended length of use, etc.), but it can also determine how easy or difficult a job may be to install or remove, or how conformable or durable a film will be for an application.

The Adhesive
Among other things, adhesives can be permanent, semi-permanent or removable and feature an opaque or clear finish. The aggressiveness of the adhesive is determined by installer ability or preference, while the quality of the adhesive is determined by the needs of the customer and the application.

The Liner
Liners are typically paper-based. Examples include white kraft, glassine or polycoated paper, but could also be film-based for specific uses. The liner is instrumental in the performance of the film during the finishing process, ensuring a smooth adhesive surface and preventing air bubbles in the finished graphic. The more smooth the liner, the more smooth the adhesive. Smoother adhesive brings better wet-out or non-silvering in the finished graphic. Higher quality liners provide improved stability in the laminating process, resulting in faster, more consistent laminating speeds.

Selecting the Right Film
How do you know when to choose one film over another? The common denominator of all film selection is matching the film to the job. It is the application that truly "categorizes" the film. Whether you are in need of a base film, over-laminating film or both, the best way to select the right film or film system is by determining if you need an economy-grade, an intermediate or a high-performance film or film system.

Click here for a larger view of the chart.

Economy Films
Economy films are designed for short-term indoor and outdoor applications. These films are generally ideal for flat to slightly curved surfaces and feature average film clarity, cleanliness and smoothness. Typical applications include:

• Wall graphics
• Tradeshow and floor graphics
• Point-of-purchase (POP) and retail signage

• Billboards
• Transit advertising
• Wall graphics
• Tradeshow and floor graphics
• POP and retail signage
• Outdoor signage

• Fleet and marine graphics
• Vehicle wraps (full and partial)
• Building wraps
• High-end displays
• POP and retail signage
• Outdoor signage

Communication is Key
As an installer, ask yourself the following questions so you can provide your printer with details that better meet your needs and determine what film solution will best fit your application. As a printer, the answers to these questions will help specify the right system for the application:

• What type of print quality and finish do you desire?
• In what environment will the graphic be applied (including weather conditions, lighting and to what substrate)?
• How long would you like the graphic to last?
• What film choice is going to meet your needs effectively and maximize your profitability?
• Will the finished graphic feature an over-laminate?

Answering these questions will help determine the durability, adhesive, finish and paired over-laminating film (if needed) for the specific application. From the printer's perspective, these answers present clear direction on the best film printing method and inks to use in order to maximize productivity, minimize waste and efficiently produce a finished film solution. A printed graphic will only be as good as the material's printability will allow.

Base films range in print capability for various printing methods from solvent-based to water-based and UV-curable inkjet to screen, flexo and offset printing. Additionally, base films offer a wide variety of finishes to achieve virtually any desired look, from high-gloss and bright white opaque to translucent, fluorescent, matte, reflective and more.

It is important to seek technical information on thicknesses, peel adhesion, face stock data, shrinkage, durability, chemical resistance and adhesive qualities, as well as the following applicable testing methods*. This is an area in which your supplier can help.

• ASTM D1005 - 95(2007) Standard Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers
• ASTM D903 - 98(2004) Standard Test Method for Peel or Stripping Strength of Adhesive Bonds
• ASTM D882 - 09 Standard Test Method for Tensile Properties of Thin Plastic Sheeting
• ASTM D1204 - 08 Standard Test Method for Linear Dimensional Changes of Nonrigid Thermoplastic Sheeting or Film at Elevated Temperature
• ASTM E84 - 10 Standard Test Method for Surface Burning Characteristics of Building Materials
  *Other countries have similar standards that may also be referenced.

As a printer, if you can work with your supplier to understand when to recommend an intermediate or high-performance film, you will excel at servicing your customer base while leaping ahead of your competition. As an installer, if you tell your print shop that your outdoor signage application requires an extremely durable film solution with a life expectancy of five years or more - and they respond that you need a high-performance base film possibly matched with a similar high-performance over-laminating film to maximize the profitability of the job while still meeting specifications - you have a great printer partnership and will get a successful product solution.

Click here for a larger view of the chart.

Pairing Film to Application
Let's take a look at the four most popular wide-format graphics applications for a detailed overview of how the economy, intermediate and high-performance film selections you make are executed.

Fleet and Vehicle Graphics
Choosing the right film for fleet and vehicle graphics applications has a big impact on money and time efficiency for installers and printers. When it comes to selecting the right film for fleet and vehicle graphics, installers are looking for durability, quality and ease of installation - especially when the installation surface includes corrugations, rivets and curves. Thickness of the film plays an important role in the conformability to rigidity ratio. Typically, the thinner the film, the more conformable the graphic will be against complex, uneven or curved surfaces.

The recommended film solution for a long-term fleet and vehicle graphics application is a high-performance 2.0-mil (or less) vinyl base film with a durable, high-performance 1.5-mil vinyl over-laminating film for added protection.

Additional considerations include:

• A high-performance base film that features an air-egress adhesive system for smooth graphic application.
• When evaluating base film selection, consider the various adhesion levels offered and the skill set of the installer. Experienced installers can increase efficiency by selecting a film with a more aggressive adhesive for faster installation. A beginner or less skilled installer needs a lower initial tack film for repositionability.
• It's important to select an over-laminating film that is thin, but not too thin. If the film is too thin, it increases the risk of stretching during the lamination process which can result in lifting (failure) after installation.
• With the proper base and laminating film combination, fleet and vehicle graphics can last up to 10 years.
• Allow printed graphics to dry fully for 24-48 hours, open to the air, before beginning the laminating process.

The recommended film solution for a medium-term POP display graphic is an intermediate 3.0- to 4.0-mil white vinyl base film featuring an opaque acrylic permanent adhesive, paired with a 3.0-mil flexible vinyl over-laminating film. Additional considerations include:

• Economy, intermediate or high-performance base vinyl options, depending on the application's durability requirements.
• When possible, pair base films with a matching economy, intermediate or high-performance over-laminating film.
• Consider carefully the use of permanent, semi-permanent or removable adhesives, depending on the application and frequency of renewing or replacing the graphics for the advertising or promotional campaign.
• Consider BOPP, PET or PC over-laminates for special application requirements.
• The use of an appropriate over-laminating film will extend the life of the finished graphic and delay eventual color fading.

The recommended graphic solution for a long-term outdoor signage graphic application is a high-performance 2.7-mil white vinyl film designed for solvent based, inkjet printing that is coated on one side with a permanent, opaque, acrylic pressure-sensitive adhesive, paired with a high-performance over-laminating film to match the media and durability requirements.

Additional considerations include:

• For outdoor graphics, over-laminating films provide added durability and further graphic protection from scratching, tearing and UV light.
• Should a signage graphic need to be transported, most can be rolled up, with the image out. If the image is not protected by an over-laminate, make sure the print is completely dry and protected in a plastic bag.
• During transportation or storage, avoid exposing films to extreme temperature and humidity changes.

Additional considerations include:

• A textured vinyl is often the film of choice for floor graphics due to the film's built-in slip-resistance characteristics for both indoor and outdoor applications.
• A tough, durable 5.0-mil polycarbonate film provides an ideal solution for floor graphics requiring longer term durability in high traffic areas or areas with heavy machinery.
• Polyolefin over-laminates are another good, economical choice for short-term (three to six month) indoor applications.

Jeff Stadelman, Technical Marketing Manager for MACtac® Graphic Products, has served the pressure-sensitive adhesive industry at MACtac for nearly 22 years. His expertise is in new product development, product marketing and sales, technical writing and customer technical support. His extensive experience with both pressure-sensitive adhesive products and graphic applications makes him an excellent industry resource. jjstadelman@bemis.com

This article appeared in the SGIA Journal, 3rd Quarter 2010 Issue and is reprinted with permission. Copyright 2010 Specialty Graphic Imaging Association (www.sgia.org). All Rights Reserved.