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Graphic Films meet Low-VOC Paints: Read This Before You Wrap Another Wall!

With the arrival of low-VOC paint, it's become even more important to do surface prepping and film adhesion testing before applying a graphic. Skipping these steps could result in a graphic that fails to adhere properly.

It's the biggest challenge many installers are facing today: Graphic films are not adhering to painted surfaces as reliably as they once did. What's going on? Did film manufacturers change their adhesives? No! It's all about the paint. We'll tell you more about this problem and offer you a simple, effective way to help make sure your wall installations are successful.

Paints that are low in Volatile Organic Compounds (VOCs) are now the most commonly available wall paint. These newer paint formulations are being driven by laws intended to help protect the environment – something we can all appreciate. However, the new paint formulations have reduced how well a film's adhesive can adhere to a painted wall. Because the paint formulations are protected by trade secrets, it is difficult for any film manufacturer to understand how film adhesives interact with these paints. That's why 3M has devoted many resources to learning the cause of this problem and how to resolve it.

"Graphics not adhering to walls is a very real problem for installers, no matter what film they are using," said Joe Walton, 3M advanced technical service engineer. "We have received videos from installers showing film peeling right off the wall. We've seen photos of films installed one day and they are lying on the floor the next morning."

Film Adhesion Testing and Wall Prep – It's No Longer Optional

The new low-VOC paints vary so much that one film may adhere satisfactorily to one paint, but very poorly to another. The way a graphics manufacturer and installer can be assured of a successful installation is by using the right advanced wall cleaning method and film adhesion testing before installing the finished graphics. A graphic installation failure can be costly for your business and your reputation, so rather than risk it, build time into your job estimate for wall prepping and testing.

"I've had a lot of calls about major film failures where the installer doesn't know what paint is on the wall, and they didn't do an adhesion test," said Walton. "Installers and graphics manufacturers must test film adhesion on every job. There is no other reliable option."

Testing is simple. Just clean an area on the wall using the 3M™ Enhanced Adhesion Cleaning Method (see the "Ask the Expert" column in this newsletter for specific details on this method). Apply samples of the film you intend to use to the surface. Wait 15 minutes and then measure its adhesion value as you pull down on the film. (Researchers at 3M have found that cleaning the wall TWICE with a mixture of 70 percent isopropyl alcohol (IPA) and 30 percent water can significantly boost adhesion for nearly any wall film applied to a painted substrate.)

"Every application surface must be considered contaminated and be cleaned before testing adhesion or installing the job. Isopropyl alcohol is readily available everywhere in the U.S.," said Walton. "Cleaning with it is easy, fast and economical, and proper substrate preparation makes all the difference to the success of an installation. Many installers take the time to thoroughly clean a vehicle to be sure they have a great installation. It's just as important for walls."

Still Not Enough Adhesion? You've got options!

On rare occasions, even the double washing specified in the 3M™ Enhanced Adhesion Cleaning Method doesn't increase the film adhesion to the level you desire. The solution may be as simple as washing the wall just one more time with the IPA and water solution.

Here's another option. Consider applying a high-tack film, such as the new 3M™ Scotchcal™ High Tack Graphic Film IJ39, to the substrate. The aggressive adhesive on this film provides a permanent new surface on the substrate, and allows you to easily apply any smooth wall film, and even change out graphics, if required.

With the rapidly changing formulations of paints, there is no single film or adhesive from any film manufacturer that works best on all painted surfaces. However, by establishing the best practice of testing every film you plan to use for a job, on every wall that will receive graphics, and using the 3M™ Enhanced Adhesion Cleaning Method both for the test and for the actual job installation, installers can have confidence in the performance of the graphics they install. Again, be sure to read the Ask the Expert column for specific instructions on how to test and prep walls.


Ask the Expert: How can I make sure that films will stick to walls that are painted with low-VOC paint?

Joe Walton, 3M advanced technical service engineer

This is a question that's being asked by installers everywhere. As paint manufacturers have changed the chemistry of their paints to lower the levels of Volatile Organic Compounds, or VOCs, the ability of any manufacturer's graphic film to adhere to the newer paints has changed dramatically.

But don't despair. Just as you'd expect from 3M, we have analyzed this problem and developed a solution that is remarkably simple, inexpensive and highly effective. The key is in how the surface is prepared, and then taking just a few more minutes to test the adhesion of the films you plan to use. Here's our best practice for ensuring that you can easily and successfully adhere almost any wall film to nearly any painted wall.

Preparing the Surface

Start with the 3M™ Enhanced Adhesion Cleaning Method. This method, which involves an isopropyl alcohol (IPA) and water solution and two cleaning steps, will greatly increase a film's adhesion to a low-VOC paint.

Photo of dirty cleaning cloth
  • Prepare a cleaning solution with 70 percent IPA and 30 percent water (essentially rubbing alcohol) in a spray bottle.
  • Soak a clean, lint-free cloth with the cleaning solution until it is dripping wet.
  • Clean the test (or application) area with overlapping strokes. Especially in the first cleaning, you may notice some migrated paint particles on the cloth (see photo at right).
  • Thoroughly soak another clean, lint-free cloth with the cleaning solution and wash the wall again. Researchers at 3M have found that cleaning the wall TWICE with a mixture of 70 percent IPA and 30 percent water can significantly boost adhesion for nearly any wall film applied to a painted substrate.

NOTE: Change the cleaning cloths as often as needed to avoid transferring contaminants from one spot on the wall to another.

  • Touch the wall immediately. It will feel cooler to the touch than an unwashed area, due to the alcohol in the cleaning solution. When it no longer feels cool, it is dry and you can proceed with the film adhesion test or, if you are ready, with the film installation.

NOTE: The typical time for cleaning a wall with this method is just 30 minutes for 125 square feet. And, it's OK to wash the walls as long as three days before your installation without significantly reducing the enhanced film adhesion.

Testing Film Adhesion

Photo of test strip being cut
  • Now prepare three strips of the same film for each of the films you plan to use for a given job. You'll need all three so you can average the results of your test.
    • Cut three 1-inch by 10-inch strips of the graphic film(s).
    • Remove about 2 inches of liner, fold down one inch, and then punch a hole in the tab you've created (see photo at right).

NOTE: It's important to test each wall where graphics will be installed. Because paints can easily be color matched, you may not be able to tell if one wall of a room has been painted with a different formula than the others.

Photo of spring scale
  • Remove the liner and apply the test strips to the cleaned surface so the punched hole is at the top. Use the 3M™ Rivet Brush RBA-1 to go over the strips three times to ensure good adhesion.
  • After 15 minutes, remove the test strips by pulling with a spring scale attached to the film strip tab. Try to pull at a rate of 1 inch every 5 seconds and observe both the value on the scale and the smoothness with which the film releases from the wall (see photo at right).

Here is how to assess your test results:

  • Unacceptable adhesion: The film measures less than 300 grams/inch on the scale and releases with little or no resistance.
  • Acceptable adhesion: The film measures 300-1000 grams/inch on the scale and releases smoothly and consistently with some resistance. May be removable with heat/chemicals but may cause wall damage.
  • Excellent adhesion: The film measures greater than 1000 grams/inch on the scale and releases smoothly and consistently with substantial resistance. Will cause wall damage if removed.

A film that pulls inconsistently or jerkily indicates that the adhesive is not making full contact with the substrate, even if it measures in the acceptable to excellent range. We do not recommend using a film that exhibits jerky removal.

For more detailed information on the 3M™ Enhanced Adhesion Cleaning Method and wall film adhesion testing, refer to Instruction Bulletin 5.37, "A Guide to Understanding and Applying Graphics to Common Smooth and Textured Walls".

Tip from the 3M Pros

Here is a quick tip to consider when prepping large wall surfaces. Divide the wall into sections using a 3M masking tape. Prep one section at a time to make sure an area isn't missed.

For more information on graphic materials, visit 3Mgraphics.com or locate a 3M distributor.