Successful Exterior Rough Wall Wraps

Graphic film applications on rough exterior walls pose unique challenges for manufacturers and installers. But when well executed, these types of graphics can be both visually striking and long-lasting. The key is to invest the time necessary and use the proper materials, tools and techniques at each stage of the project.

Like many projects, proper and thorough preparation is key to the ultimate success of a graphic on a rough wall. Consider the following when planning your next exterior wall project.

Wall Surface Texture

In any discussion of a “textured” wall, installers should understand and differentiate between the individual components of the wall. These include:

• The wall’s finish-Meaning the actual surface to which the graphic will be applied. The finish may be paint, varnish, wallpaper, a composite material or a bare substrate such as unfinished cinder block.
• The substrate-Meaning the supporting structure of a wall, such as brick, concrete block, stucco, etc.
• The texture-The visual or tactile feeling that every surface has. Rough walls present challenges with their moderate high spots and low spots, and can range from just a little texture (like fine sand paper) to heavy texture (like brick). When working with these surfaces, extra effort and more time?consuming application techniques are needed to conform the film to the texture. A film designed specifically for textured surfaces can be employed successfully with many other unsmooth textures. However, substrates made from mostly loose particles, such as loose sand-textured block, should be ruled out as candidates for applications.

Wall Surface Preparation

It is extremely important that the surface of the wall be properly prepped. Contaminants on the surface, such as dust, dirt, grease, and loose particles and paint will cause the film to stick to the contaminant instead of the substrate. Extra attention should be paid to edges and corners. When cleaning walls, avoid soaps or preparations that contain waxes, oils or lotions, as these substances will impair adhesion of the graphic. When working with a concrete block wall, it may be necessary to use a power washing device, or to hand-wash the surface with a stiff brush and detergent cleaner. This step should be followed by a clean water rinse, after which the surface should be given at least 24 hours to dry completely. Loose mortar should be whisked off with a stiff-bristled brush.

Any existing damage should be repaired so that the wall is in like-new condition. If walls are to be painted, two coats of primer followed by two coats of a high quality semi-gloss paint are recommended. Recently painted walls should be given at least five days for the paint to fully cure, per 3M, or longer depending on the paint manufacturer’s instructions. Additionally, the wall should still be dusted before application of a graphic. If it appears that the paint-to-substrate bond is not strong, this is an important warning sign that a graphic may not perform as expected.

Testing the Film Adhesion

Performing a small-scale test in advance of the complete application is an essential step that can help alert installers to any problems and prevent wasted materials and effort. Apply a sample of at least one square foot to the textured wall, using the same tools and techniques as you would for the full graphic, and leave it in place for at least one week. After this time has elapsed, check for good adhesion and removability before proceeding with the full application. Signs of trouble include popping up around grout lines, or peeling the paint upon removal (an indication that the wall was painted without primer).

Even after a successful spot test, it is important to remember that the soundness of the wall will vary from spot to spot, and a successful test is not a guarantee of consistent results over the entire installation area.

Slow and Steady Application

After thorough preparation and testing, the complete graphic can then be applied. 3M has a patent pending on the use of heat and rollers to install wall graphics and the following steps relate to this process.  

The graphic can be temporarily positioned on the substrate using masking tape. In a good application, the texture of the wall will hold much of the film away from the surface while the installer positions the graphic. The texture will also allow an escape route for air underneath the graphic. If there are minor bubbles or wrinkles when the film is first tacked in place, they will likely be resolved as the film is heated and shrinks to conform to the texture.

After tacking the graphic in place, the installer can proceed to use a heat gun and roller to seal three of the four edges, leaving the remaining edge as an escape route for air. Rates at which graphics can be applied vary by manufacturer. For example, 3M Scotchcal Graphic Film for Textured Surfaces IJ8624 should be applied at a rate of two inches per second (approximately 50 square feet per hour), while 3M Envision Print Wrap Film 480Cv3 can be applied at three inches per second (approximately 75 square feet per hour). Although this can be a slow and tedious process, working at a deliberate and consistent speed will help ensure optimum results. Always overlap each pass with the roller by 50 to 75 percent to help the film conform.

If blisters or burns occur, installers should make their next pass slightly faster. Bubbling is a sign that the installer should speed up and apply more pressure. An air release tool can be used to push the air out of any bubbled areas, after which the section can be reworked with the heat gun and roller.

After the application is completed, installers can seal the top edge of the graphic with a clear silicone caulk to prevent water from running behind it. This can boost durability in an outdoor application.

Removal Tips

With a proper application, outdoor graphics on rough walls can be expected to last for six months, and possibly much longer in good conditions. When the time comes for removal, installers should know that removing wall graphics is quite different than removing wraps from semi-trailers and vehicles. Installers should use both hands-starting at the top of the graphic and pulling it down slowly at a consistent 120 to 180 degree angle. Heat can also be helpful in removal, as it softens the adhesive and increases the film’s elasticity.

Training is Key

These guidelines present a high-level view of the process for applying graphics to rough walls. As with any skill, there is no substitute for experience and proper training. Installers should seek out any training opportunities made available by their graphics manufacturer or materials supplier to gain hands-on experience with many different substrates and learn the intricacies of the process. These training sessions are a vital part of guaranteeing success in this challenging application. Once trained in the proper rough wall technique, installers will have a valuable skill in helping create eye-catching and long-lasting graphics.  

* From the 2013 issue of WRAPS magazine.