by Cassandra Balentine
A variety of media options are available for window graphics. The type of adhesion helps determine if a wet or dry installation technique is best. A wet application is recommended for solvent-based adhesives. For water-based adhesives, dry method is preferred.
“There is no one-size-fits-all choice when it comes to window media,” comments Kitt Jones, application specialist, Roland DGA Corporation. “Whether you do wet or dry installation for these graphics is based on your ability—or your installer’s—to achieve a clean and bubble-free install.”
From opaque and clear to perforated and air egress features, window media options—both vinyl and film—encompass a variety of differentiating factors. There are advantages and disadvantages to both wet and dry application techniques.
In general, wet apply is acceptable for clear and opaque media. “When printed and installed properly it gives the appearance of direct printing on glass,” explains Jim Halloran, VP, sales and marketing, Lintec of America, Inc.
It is also ideal for standard media—both cling and pressure sensitive—that do not feature air aggress technology. This includes static cling or any low-tack adhesive product without air egress.
“A properly performed wet install will give the best, clearest look. However, it can be costly to hire professional installers to get the desired appearance,” says Gary York, wide format specialist, Agfa Graphics North America.
When a wet application isn’t appropriate, installers look to the dry method. This is preferred for perforated window media options. Stephanie Kline, product manager, Arlon Graphics, LLC, shares that this is due to the potential for liquid getting trapped in the holes and causing the graphic to look blurry.
Mark A. Elvester, senior technologies, technical service, 3M Commercial Solutions, suggests that the holes in perforated window film have the effect of adding air release to the film, eliminating the need to use soap and water to get an application without air bubbles. He says that if the perforated material features an overlaminate, water could get trapped and actually make it function poorly.
For window media options that feature an air-release adhesive, a dry method of application is recommended. “The characteristics of these types of materials make them easier to apply so a wet application isn’t necessary,” comments Brian Cheshire, business unit manager, Kapco Graphic Products.
Halloran agrees, noting that pressure-sensitive media coated with an air egress liner provides channels for the air to pass through when applying the graphic.
Karin Biel, marketing and design, Aslan, Schwarz GmbH & Co. KG, adds that the structure of air release channels is very fine and almost invisible. After application they may be visible at short range, but after some time—depending on temperature and humidity—the structure is reduced to a minimum due to the adhesive.
York says that a dry air egress product can be installed by novice users with decent to good results. “Print service providers (PSPs) who provide a dry install product can raise their profit margin by charging more for the graphic since it will save the end user a great deal of money by not having to hire an installer,” he suggests.
Considerations for Wet Apply
Both wet and dry installation methods for window graphics come with advantages and disadvantages. For wet applications, benefits include movability and a clean application. However, the process can get messy and is affected by the environment.
Before selecting material for a window graphic, the installation method should be considered up front, keeping in mind the installer’s skill level as well as the environment the graphic will be placed in.
Cheshire says the primary advantage of a wet application is a smooth, bubble-free finish. “This is especially critical when working with a clear film because you can see the adhesive,” he offers.
Matt Buckley, wide format specialist, GPA, Specialty Substrate Solutions, agrees, noting that he always recommends wet applying window film because it results in a better bond to the glass while avoiding bubbles.
Kline explains that wet apply installations are easy to reposition on the window after application. “Application fluid acts as a lubricant that allows the installer to move the vinyl on the window to find the right position of the graphic.”
According to Halloran, wet apply is superior if graphics need to be tiled together. “Aligning graphics seams are easier when the film can be moved around on the glass while wet,” he says.
“Wet application allows the installer to chase air bubbles out with film that doesn’t have air release built into the adhesive,” explains Elvester. “The disadvantage of a wet application is that the small amount of water left under the film turns a milky color for a few days while it dries through. The customer has to wait during this dry time for the graphic to look as it is intended.”
Darrell Adams, VP, Newlife Magnetics, LLC, believes that especially for window cling media, wet application helps remove trapped air bubbles from behind printed media. “Materials that use the micro-suction technology can achieve a strong holding force and clear transparency once all bubbles are removed. This type of application can last for as long as two years.” He points out that some cling materials are made in a way that the air trapped behind the media can escape on its own and be dry applied.
David Timmerman, regional technical specialist, Avery Dennison Graphics Solutions, agrees, and suggests reaching out to the manufacturer or doing a quick test to ensure adhesive is compatible with a wet application. “Adhesives that work well with wet application are solvent acrylic based. If emulsion-based adhesives are applied using the wet application method, the adhesive may appear milky due to the fluid causing adhesive whitening,” he cautions.
Nate Goodman, product manager, Drytac, cautions that wet installation can be messy and requires more knowledge and skill compared to certain dry applications. Additionally, the inks and films need to be resistant to the application fluid and the amount of pressure used during the installation.
Water management is critical, offers Andreas DeGroot, senior marketing manager, Sihl Inc. “Where the water goes, drips, and pools is important to know—especially on an outside install. Nothing is worse than a beautiful graphic on a nice clean widow and having the sill and wall below the graphic streaked with dirty water drip marks. Include in your budget some time to clean up afterwards, maybe even hose down the wall and sill. A better step is to have in the contract that the owner will prewash the window, sills, and wall to prevent unnecessary loss of productive time.”
Tamara Pitman, product manager, and Kristina Devine, senior marketing and pricing specialist, Coveris Advanced Coatings, note that if the installer is using a premask for a wet application to ensure it is completely dry before removing it.
“It is critical to remove all application fluid and any air trapped underneath the film to get maximum adhesion when using a wet installation method,” adds Timmerman. “It is best to squeegee from the center at the top of the film, moving out toward the edges of the graphic and removing the liner as you go.”
On the other hand, Dennis Brunnett, technical service specialist, FLEXcon, points out that if too much water is squeegeed out of a wet applied window graphic, it can diminish adhesion to the window.
Weather is another important consideration. “Because cold makes adhesive less aggressive, adding the wet method can make the adhesive slow to adhere and limit the installer’s ability to remove the premask,” says Buckley.
Halloran adds that it is important to understand the environment where the installation is going. “Most adhesives need to be applied above 40 degrees Fahrenheit, which can be challenging on an exterior window in the Winter up North.”
Too much heat is also an issue. “If it is too hot outside, the material becomes flimsy and is hard to handle. And the heat of the window can dry the water too quickly, making it hard to get the application completed without wrinkles. Even the best installer will leave a thin layer of water behind the adhesive.”
Jones points out that wind is another environmental factor. “Since wet mounting doesn’t allow for immediate adhesion, wind can cause the media to sag or blow off during install, and can even peel the vinyl off completely.” She says painters tape helps prevent this, but it’s best to avoid performing installation on windy days.
Wet applied graphics often require a follow up after the application fluid has dried out. “During the visit the tape needs to be removed to ensure all the edges are down tight and to trim the graphic away from the window seals,” says Jeffrey Stadelman, marketing manager, Mactac Distributor Products.
Dry applications are often an easier install because they don’t require time to dry. Aqueous adhesives are typically best dry applied, since they will often soften and become cloudy if water is used during installation, says Goodman. He adds that window films, as well as adhesives patented as bubble free, are best dry installed.
Adams suggests that in most cases, store personnel are capable of applying bubble-free materials that are installed dry. “However, most bubble-free materials feature very small holes that allow the air bubbles trapped behind the material to escape. Usually these holes create some distortion in the material that can be seen up close and prevent the maximum optical clarity of transparent films.”
Brunnett points out that that while dry apply is ideal to avoid distortion of the adhesive, it can be difficult to apply compared with wet application. He says that application methods differ between professional installers and non-installers.
Dry application allows less room for error due to the strength of the initial adhesion, according to Timmerman. “Low-tack tape can place the film correctly while the liner is still attached. It is best to squeegee from the center at the top of the film, using overlapping strokes and removing the liner as you go.”
“The dry application is immediately finished if the graphic adhesive has air channels or is perforated for bubble-free window graphics,” says Elvester.
Buckley suggests that PSPs ensure installers are aware that permanent adhesives can bond quickly to glass, giving them no time to reposition graphics. “Installers should preposition graphics before actual application using tape, then squeegee graphics from the inside out using overlapping strokes, taking care that the graphic does not come in contact with the glass before the squeegee pushes down.”
Stadelman suggests that the best advantage of a dry application is that the install time is cut by up to 50 percent, which saves a significant amount of money.
The dry apply method should work with all adhesive types, including emulsion and solvent. “During installation, this method is more likely to show squeegee marks, but these tend to disappear over time,” adds Kline.
Similar to wet apply, environmental concerns are factored into dry application. Buckley says to avoid hot weather. “If graphics are dry applied during hot conditions or too hot surfaces, the adhesive can become very aggressive. Also, if the installer is not experienced, it can be easier to trap air under the graphic resulting in unsightly bubbles.”
Marcel Medved, business development manager, Continental Grafix USA, recommends that for dry applied window media, windows need to be clean, dry, and above 50 degrees Fahrenheit. “It is also critical to trim the graphic back one eighth of an inch to one fourth of an inch from the frame or seal. This prevents graphic failure during expansion of the glass caused by temperature changes.”
Certain media factors can have an impact on the ease of installation. “Media thickness, the size of the graphic, the number of seams, the height off of the ground, and air egress liners are all ways that product composition can help or hinder installation,” suggests Brunnett.
Pitman and Devine note that when dry mounting, keep in mind that if the product is 6 mil or thicker, it applies without creasing. If the product features air egress adhesive, it usually applies bubble free. They suggest using a felt squeegee or applying a premask for application. “Use a product with a removable adhesive. If mounted incorrectly, you could take it off and start again.”
Kline says that dry applications run the risk of air bubbles getting trapped between film and glass. “This method requires professional installers experienced in installing dry while using a film that does not have air egress technology.”
Elvester agrees, stating that if there is no air release, there is a greater chance that there will be trapped air somewhere in the graphic.
Installer Points and Tools
In addition to knowledge on what media works best with what type of application type, installers—both novice and professional—benefit from application tips on preparation, tools, and testing.
“The first question I would ask is if the graphics will be professionally or self installed by the end user. If they are professionally installed, I would provide the installer with a data sheet from the manufacturer. If they are going to be self installed, I would prepare application instructions for the end user,” suggests Cheshire.
Goodman says that no matter the installation method used, it is important to clean the window beforehand with soapy water, a window squeegee, and a lint-free cloth.
Elvester recommends a five-inch stainless steel scraper for both wet and dry applications. Even after the window is washed, leftover small particles will raise the film and cause visible defects. The stainless steel blade is less likely to scratch the glass than a carbon steel blade.
If installs are to be handled by the end user, York recommends PSPs include a squeegee and some sample directions. “For instance, a restaurant employee who normally operates restaurant equipment might need basic instructions on how to remove the liner to apply the graphic,” he offers.
Elvester also suggests performing a sprinkle test of water on the window. “If the water beads, use Bon Ami or Soft Scrub cleaner to remove the wax residue left by other cleaners. Always use a rubbing alcohol to clean the window, not a window cleaner such as Windex, or a wax residue will be left behind and result in poor graphic film adhesion.”
Set to Install
Window graphics provide an excellent option for a range of markets, including décor, retail and point of sale, and vehicle graphics. However, with so many solutions it is important to understand which media is the best choice for a particular job. The type of preferred application method—wet or dry—helps to narrow down the selection. DO
Nov2016, Digital Output