By Elizabeth Quirk
Digitally printed wallcoverings are used in both residential and commercial environments. Designed for spaces with heavy traffic, public access, or in the presence of direct sunlight means added protection may be necessary. Applied in a number of ways—liquid lamination, roller, brush, or spray—coatings help prevent fading, minimize damage, and enhance the visual properties of a print. They are designed with flame retardancy in mind, as most wallcoverings require certification against fire hazards. The cost of a coating is minimal and with the number of positive features it offers, from use.
According the Wallcoverings Association, there are three categories that contract wallcoverings usually fall into. These include, Type I (Light Duty), Type II (Medium/Heavy Duty), and Type III (Super Duty). Type I is designed to be used in areas of light to moderate traffic; Type II is for high-traffic areas, such as public spaces; and Type III for heavily traffic areas where greater wall protection is needed.
Wallcoverings are currently one of the fastest growing market segments in digital printing. Many times PSPs consider liquid coatings to reinforce the final print and maintain the high level of quality that drives its popularity. Chuck McGettrick, sales manager, Marabu North America, argues “not only will liquid coating add significant life, typically doubling the life of the ink, it will also give the added durability that most wallcovering customers are looking for.”
The primary considerations for coating a wallcovering, according to Jessica Blevins, product specialist, S-One Holdings Corporation, is if the product is installed in a commercial environment where Type II standards need to be met, or if the wallcovering is exposed to a high amount of traffic within that space.
“Adding a top coat to a digitally printed wallcovering protects the ink and provides added resistance to abrasion, crocking, cleaning, stains, and colorfastness,” notes Blevins.
Coatings are applied after the graphic is printed. According to Roy S. Ritchie Jr., president, DreamScape, determining the need for a coating on a wallcovering requires the PSP to understand the durability expectations of the end user. If the client indicates that the wall will be in a public space with heavy foot traffic, then it is best to include a protective coating to increase the abrasion resistance of the print.
“Nobody wants to see scratches or scuffs on their new wallcovering. Most commonly, I see the need in commercial areas,” adds Ritchie Jr.
Alternatively, if the wallcovering is in place for a small amount of time or the addition of a coating may detract from the intended visual appearance, a coating isn’t necessary. This is why it is important to work closely with the customer to achieve their intended vision.
Coatings are also applied for printability. “Durability and surface appearance are also impacted by coating. Typically, a coated surface tends to deliver a more desired look compared to an uncoated surface. In addition, coated media tends to be more durable to abrasion and wash resistance,” states Kelly Lawrence, marketing manager, Lubrizol Digital Print Solutions.
There are many application choices when it comes to coating a digitally printed wallcovering—liquid laminator, brush, roller, or spray. Use is decided based on a number of factors, from type of substrate to the volume of the material being processed and time constraints.
A liquid laminator is a cost effective, efficient, and consistent way of coating wallcovering material. The laminator uses a metering rod to lay down a consistent, metered film thickness across the entire surface of the media.
“It is really the only way to coat large rolls of media as the laminator cures the coating using infrared heat, so the material is dry when it is rolled up on the take up side,” says McGettrick.
Blevins agrees, to ensure a smooth, consistent coating, liquid topcoats should be applied using a roll-to-roll laminator.
According to Ritchie Jr., most DreamScape users prefer the roller option because it is inexpensive and easy. They buy a roll of wallcovering, print it in their shop, then send the printed roll along with a gallon of coating to let the installer apply it. “That is the easy way for most PSPs, but not necessarily the safest. Best practice would be to have the wallcovering protected before it leaves a print shop, this way there aren’t any mishaps during installation,” he suggests.
The application method may depend on the substrate. “In general, for smooth surfaces, paper gravure methods are very common. Fabric, depending upon the coarseness of the weave, typically uses a knife over roll method of application for continuous media. Brushing and spray are typically used for pieces of work like framed art canvas,” suggests Lawrence.
The amount of media requiring a coating at one time in addition to the project’s turnaround time should also be considered. “While a brush or roller could be utilized to apply the coating, this method does not offer an efficient workflow or cost-effective solution for high volume orders. The liquid roll-to-roll coater provides a dried, ready to cut and/or ship product, where the roller method requires extra space and dry time for each panel,” says Blevins.
According to McGettrick, when coating by hand, one would have to wait about an hour for the coating to dry. Hand application is best suited for small-sized pieces rather than whole rolls of media.
Depending on location, a wallcovering may need to be fire retardant. Coating usage should take this into consideration.
Lawrence explains that in general, wallcoverings need to be flame retardant due to potential fire hazards. In order to achieve this, certain certifications are required. Also, environmental regulations limit the type of media used as a wallcovering. For example, PVC-based substrates that are inherently flame retardant cannot be used as wallcovering in certain parts of the world because of the potential for toxic gas release in case of a fire.
“Alternatives to PVC are acrylic polymers formulated with flame retardant additives to be able to pass the relevant flame retardant tests—both the base media and the coating needs to be flame retardant so the final wallcovering can pass,” adds Lawrence.
According to Ritchie Jr., certain coatings have minimal impact on the overall flame characteristics of a wallcovering. However, solvent-based coatings tend to be flammable, while many water-based coatings are not. He argues Lawrence’s point and suggests users be cautious of coatings that contain fire retardant additives or inhibitors, as these special additives can sometimes create regulatory problems with ingredients such as heavy metals or arsenic.
DreamScape recommends a water-based coating used in combination with a base wallcovering that has passed flame tests.
McGettrick states that the fire retardancy comes from the media itself rather than the coating. When it comes to Type II it is important to start with a wallcovering that is certified to this standard if one is looking for fire retardancy for a specific application.
A good coating adds life to a printed wallcovering by protecting the surface from scuffs, scratches, and general ink abrasion. PSPs offer coating as a service knowing the additional cost will pay for itself.
In Ritchie Jr.’s opinion, the outcome of coating a digitally printed wallcovering justifies the cost. “The coating itself adds somewhere between five to ten percent onto the overall cost for large projects, and ten to 15 percent for smaller jobs,” he cites.
Blevins explains that the general price of adding a topcoat to a wallcovering is based on the method used to apply the coat. The speed of the roll-to-roll coater or whether the roller method is used could add significant labor costs.
Depending on the application method used and the container size—quart, five gallon bucket, and 55 gallon drum—purchased, the cost will generally be between ten to 25 cents, according to McGettrick. Utilizing a liquid laminator keeps costs on the lowest end of that spectrum while spraying with a high-volume, low-pressure gun will be on the higher end.
Lawrence adds that the performance benefits such as scrubability, stripability, flame retardancy, print quality, and durability to lightfastness need to be weighed against the costs added to the base fabric. She says, “the relative costs may be two to three times the cost of the untreated base media.” This expense may be reduced however, as demand and volumes increase.
Coatings for Wallcoverings
Here are some coatings available for use with digitally printed wallcoverings.
EFI Armor UVF is a non-yellowing, clear roll coat developed to shield printed graphics on flexible materials from sun and element exposure. According to the company, it is tested to guard printed graphics up to five years without cracking or peeling. Its chemical resistance enables textured wall graphics to be cleaned on contact by everyday cleaning supplies. EFI Armor is a UV-curable liquid.
DreamScape’s DreamGuard Protex 3 is a water-based clear liquid laminate formulated especially for DreamScape wallcovering products but can be applied to any vinyl surface. It can be used with or without a laminator. Users apply directly on the wall with a paint roller. According to the company, coverage per gallon is estimated to be 1,000 square feet but varies depending on method of application and texture of surface.
The PrintRite portfolio from Lubrizol includes a range of coatings for digital print film applications, for use with solvent, eco-solvent, UV-curable, and latex inks, and for use with aqueous pigment or dye-based inks. Designed to cure at low temperatures, the coatings are ideal for film applications, especially on polyethylene. When coated and dried under recommended conditions PrintRite film products can be used on polyolefins without a primer.
Marabu offers its ClearShield Wall Armor. It exceeds Type II certification while protecting a print from scratches. In addition to being compatible with latex, eco-solvent, and UV-curable inks, ClearShield Wall Armor provides added stain and abrasion resistance, as well as fire retardancy. ClearShield Wall Armor can be used on most automatic flood coaters or applied using a nap roller.
Under S-One’s LexJet brand, EnduraCoat UltraMural is a flat matte, fade- and mold-resistant coating for digitally printed wallcoverings. It also offers EnduraCoat Color Capture Wallpaper Matte, which is designed specifically for digitally printed wallpaper. Offering a matte finish, it is a highly flexible, superfast drying acrylic aqueous clear coat.
Working with Coatings
Digitally printed wallcoverings are used in nearly any environment and need to be protected, especially if they are designed for spaces with heavy traffic or in the presence of direct sunlight. By coating a digitally printed wallcovering, one is guaranteed to see less damage and fading to the print, as well as increased abrasion resistance.
Jan2017, Digital Output