Boosting Adhesion in Dry Applications

The line is seemingly split right down the middle between accomplished, professional installers and less experienced applicators. The bottom line is your choice of wet or dry application will depend on the application situation and your skill level. While beginners often start off with wet applications, abandoning the solutions and installing dry offers many advantages.

Doing It Dry 
There is no question that dry applications offer many advantages for professional installers and this is the preferred method most of the time. Fleet applications, for example, demand dry installations.

“A lot of sign shops are still putting vinyl on wet. Professional fleet vinyl installers never use application fluids,” says Rob Ivers, a professional vinyl installer and trainer in Raymore, Mo. “If you use the wet method of application, you are going to have problems no matter what.”

Ivers insists that installers need to learn about the characteristics of different vinyl media and how to apply the film dry, and for good reason. There is an admitted learning curve with dry applications and the old adage that practice makes perfect certainly applies. Dry applications, however, will increase you productivity and save you money spent on wetting solutions.

“Applying the vinyl dry will save the time of having to purchase the fluids, apply the fluid, wipe up and clean up the mess from the fluid,” says Ivers. “With wet application, you have to squeegee four to five times to try and drive out the fluid.”

Dry-Only Media
Professional installers use premium vinyl because they cut and install with more ease and last longer. While earlier generations of vinyl lent themselves to wet applications, the latest lines of premium media from major manufacturers are designed to boost adhesion without wetting solutions.

“Most installers that are using wetting solutions are using less premium vinyl,” says Nathan Franzblau, founder of the Professional Decal Application Association, an association of independent certified installation companies. “There are degrees of vinyl ­ premium and economy. The economy vinyl can be somewhat aggressive and more difficult to install dry.”

New technologies have allowed manufacturers to design films with channels in the adhesive that allow air bubbles to be pushed down without leaving wrinkles in the vinyl. Avery’s EZ films and 3M’s Comply are two good examples. These new films are also more forgiving in terms of repositionability.

Most manufacturers do not recommend wetting solutions with next-generation films that feature these channels and pockets. In some cases, wetting solutions may even void the warranty on the film. Actually, wet adhesion is typically only recommended for PVC films. PVC is a thermoplastic that is strong and especially resistant to water, acids, and abrasion.

Preparing for Dry Application
Now that you have decided to apply dry, you’ll need to gather the appropriate tools. You’ll need a squeegee and an air-release tool to address any bubbles that many appear. Bubbles occur due to outgas, which is the vaporization of a solid or liquid. Outgassing can occur in some plastics and insufficiently dried paints, resulting in adhesive failure of films applied over them.

You’ll also need a low friction sleeve, a heat source, a razor knife, a rivet brush, masking tape and a marking pencil. A chalk-like marking pencil is not recommended.

If the vinyl graphic has been rolled up, be sure to flatten it out before attempting to install it. It is also important to understand the appropriate temperatures and other environmental conditions that produce the best adhesion. (You can learn more about these properties in an article entitled “Considering Environmental Conditions” in this same section.) It is also critical that the surface is thoroughly cleaned.

How to Apply Dry
Next, remove the vinyl from the backing paper by peeling it back from one corner. Baking paper is also known as a release liner or carrier and is the portion of the pressure-sensitive construction that protects the film’s adhesive before it is applied. The backing readily separates from the film immediately before it is placed on the substrate or target surface. Be sure to leave the pre-mask (application tape) on at this point. Pre-mask is the pressure-sensitive tape used to transfer a cut graphic from its liner to the substrate or to protect a given surface.

Next, locate where to position the graphics and mark the spot using small pieces of masking tape. If the graphic is large, tape it into position securely with masking tape. If the graphic is less than eight square feet, remove the entire liner. Position the graphic on the marked points using light tacking pressure.

Once you are satisfied with the position, begin at the corner and press it down using moderately firm, overlapping strokes, making sure the applicator is flat with the substrate along the entire length of the stroke. Hold the squeegee at a 50-70 degree angle to the surface. The flatter the squeegee the better. Overlap all strokes by about 50 percent.

Boosting Adhesion
Whatever the tools or technique, use enough pressure to make sure the graphic firmly adheres to the substrate. Pre-masked graphics require additional pressure, but it is important to use the application tape because it allows you to rub the graphic without damaging it or the ink. Different films have different levels of abrasion resistance.

Once the vinyl has been applied, you need to remove any air bubbles and tenting around rivets by using the air release tool. Heat may also be necessary to work out the bubbles, depending on the application.

Wait at least five to 10 minutes after the application to allow the adhesion to build to the functional bond level. The idea is to get ultimate adhesion; the characteristic of a pressure sensitive film that prevents it from being removed after it adheres to a substrate for a period of time. Although the time needed for ultimate adhesion typically occurs within about 24 hours after application, it can vary based on the types of adhesive and substrate used and the conditions under which the film was applied.

Until a functional bond is achieved, it is risky to remove pre-mask or allow a vehicle to be transported. Once you remove the pre-mask, re-squeegee all graphics edges, overlaps and seams using firm pressure. Use a squeegee with a low friction sleeve to prevent scratching or damage to the graphic. The re-squeegee is an absolute must on all edges of the decal to ensure its ultimate adhesion.

If the adhesion is not adequate and the graphic must be put into service right away, then carefully re-squeegee the graphic (again, using a squeegee with a friction sleeve). Re-squeegee the film using greater pressure, overlapping strokes. This will help improve the adhesion of the graphic.

If you are still not comfortable with the dry method, or need to learn with wet applications may be appropriate, check out our article entitled, “When to Use Wet.”

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