Understanding Vinyl’s Technical Specs

Attention, pressure-sensitive adhesive (PSA) vinyl do-gooders: It’s time to increase your knowledge of all things sticky. I presume that most of you load vinyl rolls into the plotter, output your design and stick it to whatever your customer needs without major problems. But, what happens when something does go wrong? What happens when that graphic becomes kryptonite?

Do a little homework before selecting vinyl to avoid potential headaches during, and after, the application. This column takes aim at all the technical jargon that typically accompanies a PSA film — specifically, what’s important and what’s not.

Adhesive types

Why are vinyl graphics so popular? Because they stick to just about everything? Not exactly. One of the first things to look for in your vinyl brand and series’ technical bulletin is its adhesive. You will typically find this under the product description.

Generally, there are two types, permanent and removable. The biggest difference between them is the final bond the film makes to the substrate. A removable adhesive’s bond is engineered to be weaker than that of a permanent adhesive. This allows the adhesive bond to be broken more easily by mechanical means, such as picking at it with a finger, which makes it much easier to remove. In contrast, a permanent adhesive forms a much stronger bond, which requires more mechanical power to break — particularly, a heat gun and patience.

Other specifics also require special attention. Check if your vinyl series has a "solvent" adhesive system or "solvent-acrylic" adhesive system. If the word solvent isn’t in the description, your vinyl probably has a waterbased adhesive.

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Typically, waterbased adhesives help minimize costs in more economical calendered films. Waterbased adhesives, which are sometimes used on specialized films that may be used indoors for such short-term projects as POP or exhibit graphics, conform to building fire codes. $image1

Carefully match the adhesive type to the application. Never perform wet applications with waterbased adhesives, because liquids can cause the adhesive to turn mushy and slow tacking time.

It’s also important to understand the graphic’s environment. Will temperatures vary widely? Is it very humid? Will chemicals or solvents be used around the graphic? If the answer to any of these questions is "Yes," then I can’t recommend a waterbased adhesive. Rather, consider using a film that features a solvent-based adhesive.

Solvent-based adhesives, which tend to be used on intermediate and high-performance films, suit a wider variety of applications. These adhesives can be used in wet applications, and tend to have greater resistance to chemicals and solvents. However, weeding with them may prove more difficult. Determining your adhesive type before you select your film will circumvent many problems, but it’s important to remember how much stress the graphic will encounter.

Dimensional stability

Although the term "dimensional stability" sounds like rocket science, it’s not difficult to understand. Once a PSA vinyl film has been developed, a series of tests determine its viability and performance in everyday applications. One key test determines, once applied, how much the film will retract or "shrink" from the substrate.

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The tester applies the film to a piece of steel, monitors it closely and measures how much the film will move over time. This measurement should be readily available in your particular film’s technical data, and it usually appears as a value such as "[less than] .004 in."

This specification is especially important when layering, seaming or overlapping multiple films together in a graphic. If those two films don’t have similar dimensional-stability characteristics, the results could be disastrous. Try explaining to your client why, after only a month on the road, a visible white space has appeared where you overlapped red and blue films with different properties. Check the specs before choosing films to avoid such situations and gain repeat business.

Historically, calendered and cast films’ stabilities substantially differed, but, ultra-calendered films closed the gap dramatically. Thus, shops can team a greater variety of films together, and clients also have more options. However, dimensional stability varies significantly between different brands and products — take time for comparison shopping.

Temperature resistance

 Let’s move on to a less "technical" film spec — temperature. The quality of raw materials used in the facestock and adhesive, and how these two components interact with each other, determine vinyl’s ability to resist temperature changes. Manufacturers will perform rigorous tests to make sure both components operate without failure within the temperature ranges stated on product technical bulletins. This value is typically expressed in Fahrenheit or Celsius.

Temperature resistance is a key factor in matching a film to an application. For instance, a moving company’s trucks travel from Miami to Madison or from Seattle to San Antonio. They’ll encounter extreme temperature changes. Make sure your film meets this challenge.

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Exceeding the product’s temperature ranges causes the face film and adhesive to separate, which leads to premature failures, such as rapid discoloring or adhesive breakdown. Temperatures lower than the stated range cause brittleness, cracking and face stock/adhesive separation. Either way, the wrong film choice adversely affects your bottom line.

Frequently overlooked specs

When considering particular films, don’t overlook key points that are readily available. Consider durability or expected outdoor life. How long will this graphic adhere if applied properly? Obviously, the job must match the film’s stated outdoor durability — don’t cut it too close. Vinyl represents a relatively small cost in most sign projects, so the few extra dollars spent on a higher-grade film could be worthwhile to ensure a quality job.

The film’s application temperature differs substantially from the substrate’s. Though the thermometer says that it’s 60° F outside, the car’s surface temperature isn’t necessarily the same. If that car has been parked in the shade all day, the surface temperature may only be 45° F. If your film’s application-temperature minimum is 50 or 55° F, pull that car out into the sun for a few hours before applying the graphic. In very hot weather, it may be advisable to pull the car inside or into shade. An infrared thermometer, which measures the temperature of any substance independent of the ambient temperature, may help you determine the target temperature.

Mils, the standard measurement of vinyl’s thickness, correlate with a film’s ideal applications. The most popular PSA vinyl films range from 1 to 6 mils. However, it’s important to understand why a vinyl-graphics fabricator would choose one thickness over another. Thin films, which are usually 2 to 2.5 mils, are more commonly used for conformable projects, such as vehicle graphics that may have irregular surfaces or rivets. Thicker films — 3 mil and above — are suitable for general signage and flat applications. User preference — some say very thick films are easier to handle, while others like thinner films for easier weeding — may be the deciding factor.

Technical filler

Manufacturers may conduct several other tests that really push the film beyond its limits. A PSA film’s technical bulletin may list tensile strength, elongation at break, and statements of adhesive power (data which illustrates the point at which vinyl will fail). Unless you’re studying chemical engineering, these values may not mean much, but the manufacturer is providing maximum product information. However, manufacturers use various testing methods, which make reliable data comparison problematic.

Whether using cast, calendered or ultra-calendered film, understand your film’s performance factors. Successful applications (and happy customers) stem from doing initial research and making sure your film choice matches the application. Most vinyl manufacturers provide technical data in their literature or websites – some digging may be required. If you have further questions, call the manufacturer directly.

Hopefully, you’ll now be able to leap 4 x 8-ft. construction signs in a single bound and letter a box truck with one hand – sorry, that’s getting a little crazy. But, if you’ve armed yourself with product knowledge, you’ll be saving the day, everyday.