11 minute read
Smooth Wall vs Rough Wall
Choosing the Proper Materials
by Jay Kroll
Back in December, I met with a sign shop owner and his installer on site down in Kalamazoo, Michigan, to try to troubleshoot why a wall mural with a material they’d used consistently for over a year was failing at the upper edges on just one particular install. The notes and conversation back and forth beforehand pointed to all of the rules being followed—cured paint, proper ICC profile, and a smooth surface. The same roll of material was used for two other murals that didn’t have any issues, and while that’s not definitive, it left enough doubt that the complaint needed more investigation. Nothing out of the ordinary, no clear source for the issue, and a problem in need of a solution.
As you picture it, what are the initial questions you would ask? Maybe you’d want to know about their technique for surface preparation. Was it really hot/cold when they installed it? Was there anything crazy about the paint they used, whether the type or the age of the paint job? What tools did they use? What about the condition of the wall? There are so many variants of “smooth” when it comes to walls that they really have to be approached individually with an eye for obstacles and complications that could negatively impact your installation.
I have said many times that the Print and Wrap community has some of the most tenacious, gifted problem solvers, needing to understand and juggle everything from color management to carpentry, electrical engineering to ICC Profiles, and having expertise in all types of materials and substrates. Every once in a while it’s good to step back and think about the basics of film, adhesive, and liner and how they relate to common wall surface types. Then we can think about how best to adjust the various pieces and parts to ensure success on every graphic installation.
Smooth Drywall
A common misconception is that smooth drywall is perfectly smooth, but look closer and you’ll see a series of small bumps in the surface that can be a challenge for some adhesive films. Drywall/sheetrock has a natural fiber texture, morphing from its basic paper base when finished with a range of paint types, roller nap thickness, and a specific finish. That uniform texture can provide a consistent substrate for most adhesives, but the specific adhesive formulation and film selection is critical in this situation. A film that is too rigid paired with a thin adhesive layer, or a thin film with a glue that is too gentle can fail if it doesn’t have a high enough bond with the surface. If the adhesive is too aggressive, repositioning panels becomes impossible, and you can count on pulling paint when it’s time to remove the graphic. There is a delicate balance to keep when gauging tack, bond, film type, and so on, and every wall is going to have its own story. Create habits where you ask good questions, create a checklist for site visits, and test and practice with the various material options and tools.
Paint Types
The paint sheen used helps set the tone for the space but also adds a variable to the mix when paired with an adhesive wall vinyl. Flat paint offers a low-sheen, non-reflective surface, but also creates a lower surface energy contact point for your adhesive. This microtexture presents a challenge for adhesive bonding that is made worse by the introduction of low and zero-VOC paints which have a tendency to outgas their curing agents over a longer period of time. Flat paint can require a higher initial tack adhesive to allow the material to grip and hold as the bond grows over time.
Eggshell or Semi-Gloss paints inherently have a little more shine, and that smoother, harder surface finish makes an ideal application surface for wall graphics. I would also add that it is critical for clean removal to make sure that the wall has been primed before painting, in a separate step. This seals the drywall paper and any loose particulate or joint compound and creates a platform for optimal paint adhesion. Failure to prime the wall will lead to failures when it’s time to remove the graphic.
Stucco/Textured Walls
Stucco or textured walls introduce irregularities, requiring materials with extra conformability and adhesives that are designed to hold on intricate surface variations. A cast vinyl or ultra-conformable calendered material is going to be best, but don’t go running for your standard wrap material as a slideable permanent adhesive might not be the best option here. Stickers applied to these surfaces have to navigate the peaks and valleys, so yes, cast vinyl is great, but these walls typically require something more high-tack to stick and hold in those nooks and crannies.
Sealed Concrete/Cinder Block
These surfaces essentially have their pores sealed, ideally with a semi-gloss or better paint, and provide a smoother, hard surface for applying graphics. Adhesives designed for these substrates still need to have high tack and strong bonding characteristics, and the films should have excellent flexibility and conformability to adhere to the variable surface.
Adjusting for Environment
The materials we use can be standardized a bit, incorporating what we know about films and adhesives to identify a few go-to solutions. Let’s take our opening install: it turned out that not only was the wall not actually smooth, but the textured surface had been quickly repainted with large defects and drips that messed up the contact between the adhesive and the wall. We know that when walls have a texture to them, either our film, adhesive or both are going to need to be able to conform to the peaks and valleys of the wall. Textured walls will be best served with a full polymeric vinyl— either calendered or cast—as this will give the best conformability, flexibility, and the least amount of shrinkage of the available options. The adhesive can be either a solvent-based or water-based acrylic adhesive. Water-based adhesives use (surprise!) water in their chemistry as a way to deliver the glue to the liner in the coating process. If you’ve ever wet applied a clear decal to a window and noticed a chalky haze that dissipates after a while, that vinyl incorporated a water-based adhesive, and that effect was caused by the water reacting with the adhesive. It can be temporary like on a window where that water is squeezed out and dried, but if it can creep behind the vinyl on a textured or porous surface, the water mix can compromise the adhesive bond. With a solvent-based adhesive, water was never part of the mix and it will generally not be affected by contact with moisture. Of course, this doesn’t mean that the substrate isn’t impacted by the presence of water like with unsealed concrete or brick applications, but that would be disruption between layers (adhesion) versus compromise or breakdown of the adhesive layer (cohesion).
Indoor smooth walls in controlled environments are generally a perfect place to use a monomeric or intermediate film and a water-based adhesive. Be sure to consider the initial tack of the adhesive, immediate and long-term repositionability and removability, and even whether the vinyl can be reused in different locations like with some microsphere beaded adhesives. When we talk about the various options, I can’t recommend enough getting your hands on a few different material options to play around, and get a feel for their strengths and weaknesses—it will pay off in the long run, and expand your expertise in this area.
Whether the installation is indoors and you’re making sure the paint is cured and clean, or outside where it may require pressure washing and a wire brush, surface preparation is key. In either case, it’s critical to ensure your surface is free of loose debris, significant moisture, or contaminants like grease or dust.
The way you install may vary, and it’s important to test and practice with your chosen materials and tools to hone your technique. Whether top to bottom or left to right, overlapping panels or butted together, you should explore both what the material is capable of and best suited for, as well as what you are most comfortable with for the type of jobs you choose to do. Textured walls and even some ‘smooth’ walls need the help of some heat and a foam roller tool that will allow the film to contour to the surface. You might use a felt squeegee to do the initial set of the graphic, but that only makes contact with the high points of the wall. The vinyl and adhesive need pressure at all points to really work it into the surface.
Every manufacturer and material is going to have its own recommendations for application temperatures, cleaning and maintenance, durability, and removability. As the multitalented print guru that you undoubtedly are, you also know that the manufacturer’s Technical Data Sheets are your go-to location for the details on the specific wall vinyl or fabric. When assembling a job, consider printing out a copy of the associated material documentation to go along with your job packet, and jot down the helpful details like the corresponding lot number in case you need to refer back to it in the future. You can also create a site visit checklist where the customer signs off on things like the wall condition, paint age, temperature, warranty details, etc… Details like these are helpful for ensuring a successful installation, but it is also nice to have the extra layer of documentation in the event something goes awry.
Speaking of warranties, your material warranty will vary by manufacturer as well and may be tied to full or partial replacement of the rolls used. While not typical, it could also cover additional elements like ink or labor, shipping or installation. However, what you warranty or cover is important to consider as well. Do you guarantee clean removal, and what does that mean? One major vinyl manufacturer has a ‘clean removal’ tolerance that allows for up to 5-10% of the adhesive to remain on the application surface! Do you warranty the condition of the underlying drywall or paint? Does your bid cover both installation and removal? Are any of these things contingent on your team doing the installation? All of these additions should be factored into your price as well, building in a little insurance for those unexpected complications.
Knowing what to charge on any job is that fun guessing game of how much is too much without being not enough…it is not uncommon for a wall mural job to be the cost of materials and print x10, so a material and print cost of $1/ SF for a 8’x10’ wall equates to a $800 job for print and installation with roughly $80 in costs. Time, travel, and installation will factor into that, but with a team of 2 and a well-prepared installation area, that job should be doable in about 30 minutes from setup to completion. This is obviously a loose calculation and the same job will be different if it’s in a residential versus commercial setting, or maybe it’s retail or a multi-location repeating piece. These are the elements of your operation that are impossible to know from this side of the screen, and ultimately you will need to determine what is best for your particular situation.
The print industry is ever-changing with new materials and applications, substrates and solutions. However, the constant in the midst of that is you, your relationship with your clients, and your particular expertise that keeps them coming back. I hope this has been a helpful dialogue to facilitate some curiosity and spark some ideas to move you along on a path of growth and success with your business.
Jay Kroll Jkroll@generalformulations.com
