Resources

WALLCOVERING 101

WALLCOVERING GLOSSARY

Types of Commercial Wallcoverings

CONTRACT WALLCOVERING
These wallcoverings are produced specifically for use in high-traffic commercial environments such as hotels, hospitals, office and apartment buildings, retail outlets, and schools. The contract wallcoverings offered by Wolf-Gordon are manufactured to meet or surpass the physical and performance characteristics established by the federal government.

Federal Specification CCC-W-408D testing guidelines for contract wallcoverings focus on 16 characteristics: Colorfastness, Washability, Scrubbability, Abrasion Resistance, Breaking Strength, Crocking, Stain Resistance, Tear Resistance, Blocking Resistance, Coating Adhesion, Cold Crack Resistance, Heat Aging Resistance, Flame Spread and Smoke Development, Shrinkage, and Mildew Resistance.

Contract wallcoverings are given a type by the American Society for Testing and Materials (ASTM) as follows:

Type I—Light duty, commercial grade vinyl wallcovering; typically 19 oz or less per 54" linear yard. Type I items must meet the minimum requirements defined by Federal Specification CCC-W-408D. These wallcoverings are commonly used in apartment and office buildings, hotel rooms, waiting rooms, and for other budget-conscious projects, as well as for ceilings and areas of light abrasion.

Type II—The most widely specified category for commercial interiors; typically 20-32 oz per 54" linear yard. Type II wallcovering must meet higher criteria for the federal specifications than Type I, for Abrasion Resistance, Breaking Strength, Stain Resistance, Tear Resistance, and Coating Adhesion. The majority of Wolf-Gordon’s vinyl wallcoverings are Type II, used for a broad range of heavy traffic applications, including hospitality, healthcare, office, retail, education, and interiors that undergo average to heavy scuffing.

Type III—The most durable of the contract wallcoverings, manufactured for use in extremely heavy traffic locations; typically over 33 oz per 54" linear yard. Type III wallcoverings must meet the highest federal requirements for Abrasion Resistance, Breaking Strength, and Tear Resistance. Although Type II wallcoverings are usually sufficient for most applications, Type III may be required for wainscot or low areas exposed to very heavy traffic by movable equipment or rough abrasion, such as in hospital corridors and elevator banks.

SPECIALTY WALLCOVERINGS
Wolf-Gordon offers a wide array of wallcovering materials for specialized applications. They tend to be highly decorative, functional, or appropriate for use in commercial interiors where a dramatic look is desired. In some cases, when greater durability is required, vinyl wallcoverings can simulate a comparable look.

Acoustical—Wallcoverings designed for use on vertical surfaces, panels, operable walls, and any place sound reduction is a primary factor. Examples are meeting rooms, offices, auditoriums, restaurants, as well as corridors and elevator lobbies. Acoustical wallcoverings are predominantly made of man-made polyester and olefin fibers, and are tested for sound absorption, yielding a Noise Reduction Coefficient (NRC) rating, which indicates the amount of sound absorbed into the wall.

Cork—An ideal example of sustainability, cork is stripped from the bark of a cork oak tree, which regenerates every 9-10 years. The natural cork is then formed and laminated to a nonwoven substrate or paper that may be colored or plain. Cork wallcoverings have a variegated texture with no definite pattern or design. They are naturally mildew- and rot-resistant, and highly permeable, offering some degree of sound resistance and insulation. In addition to a variety of distinctive patterns and natural colorways, Wolf-Gordon offers bulletin board corks and a unique high-performing cork upholstery material that has the feel of leather.

Mica—Made from crushed pieces of a silicate mineral, mica particles (aka vermiculite) are adhered to metallic paper backings to create a highly reflective mica wallcovering surface.

Grasscloth—Fibers harvested from rapidly renewable plants and grasses, such as abaca, jute, and sisal, are dyed and laminated to a paper backing for enhanced dimensional stability and to prevent adhesive from coming through to the wallcovering surface. Wolf-Gordon’s wide range of grasscloths varies from refined, fibrous textures to coarse, irregular woven alternatives. Because they are made of natural materials, there will be imperfections and some uneven shading.

Linen—A rapidly renewable resource, linen is the strongest—and oldest—natural fiber. Our linen and linen blend textile wallcoverings are produced with European linen, and possess anti-static and anti-allergenic properties, excellent breathability, and resistance to insects and microbial growth.

Paperweave—similar in look to other natural wallcoverings, paper components such as cellulose and rayon are colored with non-toxic waterbased dyes, woven into a variety of patterns, and laminated to paper backings. Paperweaves tend to provide more consistency in color than with other natural materials.

Silk—Some of our most luxurious and richly colored wallcoverings are made of 100% silk. The shimmering appearance is due to the triangular prism-like structure of the silk fiber, which refracts incoming light at different angles. Inherently natural, the material most often has a horizontal weave with characteristic slubs.

Textile Wallcovering—Offering high performance, these synthetic blends of polyester, olefin, and/or rayon are generally laminated to an acrylic backing and treated with stain-resistant finishes. Although intended as wallcoverings, many meet ACT performance standards for abrasion, flame resistance, and crocking.

Wood Veneer—genuine wood wallcoverings made from veneers of over 200 different tree species, including domestic, exotic, and burls. Both flat-cut and quarter-sliced options are offered, as well as two categories of reconstituted wood veneer walcoverings: BildenWood veneers are reconstructed through a proprietary process that uses architectural-grade lumber components of authentic species; WonderWood wallcoverings are engineered veneers that mirror a wide variety of domestic and exotic woods, composed from high-yield species sourced from sustainable tree farms. Because both BildenWood and WonderWood veneers are fabricated, they offer enhanced consistency in grain and color.

Writable/Dry Erase—flexible presentation surfaces of vinyl and polyester, laminated to woven or nonwoven backings, and commonly used with dry-erase markers as a writable/erasable wallcovering and/or projection surface, Wolf-Gordon offers several printed designs and neutral colors, in addition to a peel-and-stick option. Installation is similar to commercial wallcoverings, and dry-erase substrates may be used to cover old blackboards or whiteboards.

Wallcovering Construction

Most Type I, II, and III wallcoverings consist of three layers, each of which performs an important function:

Decorative Layer—the thinnest layer in most cases, comprised of inks applied to the top of the intermediate layer. This layer supplies the design and color of the product, which is produced using methods such as rotogravure, flexography, and screen printing, and may also have a protective polymer coating to provide added performance characteristics.

Intermediate Layer—also called the ground, this provides the surface upon which the decorative layer is printed. It also provides the background color that, while often white, can be any color depending upon the design. This layer can range in thickness from less than 1 mil (1/1000 of an inch) to as much as 20 mils, as used for heavyweight, solid vinyl products.

Substrate or Backing—the layer that is adhered to the wall, important in determining which wallcovering product will be used in a particular application. The substrate can be made of a wide variety of materials, ranging from woven and nonwoven fabrics to lightweight paper products.

The various types of backings are:

Paper Backings—used on paper-backed vinyls, vinyl coated papers, and specialty products.

Woven Fabric Backings—commonly referred to as scrim or osnaburg. Scrim is used mostly in light construction areas, while osnaburg is installed in medium–heavy usage areas, such as commercial building corridors.

Nonwoven Fabric Backings—in different grades, these offer improved printing techniques while maintaining the tear strength qualities necessary for commercial installations.

Latex Acrylic Backings—used on textile wallcoverings to allow for stability and improved hanging qualities.

Characteristics

The federal government mandates that contract wallcoverings achieve certain performance measures and testing conducted by a certified testing facility. Testing guidelines focus on requirements for the following sixteen wallcoverings characteristics:

1. 1. Colorfastness—ability to resist change or loss of color caused by exposure to light over a measured period of time.
   2. Washability—ability to withstand occasional sponging with a prescribed detergent solution.
   3. Scrubbability—ability to withstand scrubbing with a brush and a prescribed detergent solution.
   4. Abrasion Resistance—ability to withstand mechanical actions such as rubbing, scraping, or scrubbing that may tend to progressively remove material from the wallcovering surface.
   5. Breaking Strength—ability of a wallcovering to withstand a pulling force.
   6. Crocking—ability to resist transfer of color from a wallcovering surface, when rubbed.
   7. Stain Resistance—ability to show no appreciable change in appearance after application and removal of specified reagents.
   8. Tear Resistance—ability to resist the propagation of an existing tear.
   9. Blocking Resistance—ability to resist adhesion or sticking between two surfaces of a wallcovering that touch under uniform loading and temperature conditions for a specified time.
   10. Coating Adhesion—measure of the strength of the bond between the surface coating and the backing or substrate of a wallcovering.
   11. Cold Crack Resistance—ability to resist cracking of the coating or decorative surface of a wallcovering when folded, during exposure to low temperatures.
   12. Heat Aging Resistance—ability to resist deterioration of the coating or decorative surface when a wallcovering is exposed to elevated temperatures over an extended period.
   13. Flame Spread—ability to resist flames spreading at a fast rate along walls and ceiling when wallcovering is exposed to a source of ignition.
   14. Smoke Development—ability to reduce the amount of smoke that develops when wallcovering is exposed to a source of ignition.
   15. Shrinkage—ability to not shrink more than 1 percent when soaked with water for 30 minutes, and then dried.
   16. Mildew Resistance—ability to deter the growth of (fungal) mildew on the decorative surface.

Pattern and Dye Lots

During the manufacturing process, a wallcovering pattern and dye lot (aka run number) is printed on each roll. The pattern number identifies a particular design and color. The dye lot number represents a particular batch of wallcovering rolls that are printed on the same print run. The dye lot number will change each time there is a change in the printing process. Different numbers could signal variables such as changes in tonal color, vinyl coating, and/or consistency of the embossing process being used during production. Any of these variables could show a slightly different color in the wallcoverings, sometimes visible only when two different dye lots are compared.

It is very important that an installer check each individual roll in a wallcovering shipment to ensure uniformity in color and pattern. It is also important to record pattern numbers and dye lot numbers for future reference, in case additional material is required. The industry standard for uniformity requires that the installer hang three panels or strips and inspect for correctness of materials and application, before proceeding.

Types of Printing

Surface Printing—most often employed to reproduce a stencil-like effect, accomplished through the use of lightweight urethane print cylinders. The print design coincides with raised areas on the roller, obtained by removing or cutting away to leave the desired design elevated above the rest of the cylinder (like an ink stamp). Printing is accomplished by first applying ink onto the raised areas. The inked roller is then pressed against the material to be printed causing the ink color to be transferred from the surface of the raised design onto a moving web of wallcoverings. One roller is required for each color.

Flexographic Printing (aka Flexography)—similar to surface printing except the print cylinders are made of flexible materials, usually rubber. The Flexography process offers the manufacturer a technique for achieving more delicate designs than is possible with nonflexible surface rollers. Some tonal effects are possible.

Screen Printing (aka Silk-screening)—accomplished with either flat or rotary hand screens. The design image area is reproduced onto a flat mesh screen held within a frame. The screen area is covered with a resist, such as wax, which plugs or blocks all of the screen openings, except in the area of the design image. Ink is then applied to the flat screen, and a rubber squeegee is used to push the ink along the screen surface, forcing it through the openings in the design area onto the wallcovering substrate. One screen is needed for each color. This process is most often used for specialty and customized products.

Rotary Screen Printing—a high-speed production technique used to replace hand screen-printing. Ink is fed into the inside core of a rotary or round, screen mesh cylinder and an internal squeegee blade is used to press or apply the ink through the image area of the screen. The ink will not flow through the rotary screen where a resist has been used to block or seal the mesh. Rotary screen printing is used for designs where a bright, solid color laydown is required, or for expanded vinyl prints. Specially formulated ink is used to print the design, which then goes through a heat tunnel that activates a blowing agent, causing the ink to expand, and creating a three-dimensional look.

Rotogravure Printing (aka Gravure or Intaglio)—this process provides the opportunity to achieve a complete, continuous color deposit ranging from 100 percent full tone down to almost a 5 percent tone. Gravure is a costly manufacturing process because the cylinder used requires copper plating and a special photochemical engraving or etching process. Printing is accomplished via tiny cells or ink reservoirs that are engraved into the surface of the print cylinder. In contrast to surface printing, the ink is held within tiny cells engraved into or below the cylinder surface. The deeper the cell, the darker the tone printed. By varying the size and placement of each cell, varying amounts of ink can be deposited onto the wallcovering by pressing the inked cylinder against the web. Pressure causes the ink to flow from within each cell onto the wallcovering. This process is the most versatile since it can duplicate a complete range of visual effects, and is able to give an almost photographic effect.

Digital Printing—one of several non-impact technologies where an image or pattern is created, manipulated, and finalized by electronic systems, and printed by a computer-controlled printer. The process begins with a digitally generated, scanned, or photographic image, created at a high resolution. Images are generally printed with UV-resistant inks on a washable, latex-reinforced substrate, which is clear coated for long-lasting protection. Substrates include a wide variety of vinyl-embossed textures, Mylar, acetate, canvas, window film, self-adhesive, natural and fabric materials.

Pattern Matches

Pattern matching is required for wallcovering designs with a repeating pattern. The repeat is the vertical distance between one point on the pattern to the next identical point. Patterns may also repeat in the horizontal direction. A repeat can range anywhere from an inch (or less) up to the full width of the roll. When installing wallcovering panels, there are three types of pattern matches that are dependent on the repeat: Random Match, Straight Match, and Drop Match. And, depending on the type of pattern and/or embossing used, each strip may require either a Straight Hang or Reverse Hang.

Random Match—when a design has no specific match point, each strip can be positioned randomly. Stripes, textural patterns, and grasscloths are examples of this type of match. It is generally recommended to use a Reverse Hang technique for these types of patterns—alternating the top and bottom of each successive strip—to minimize visual effects such as shading or color variations from edge-to-edge. In cases where a design has a directional quality, a Straight Hang may be indicated. Note: Random match wallcoverings will produce less waste, since there is no repeat distance to take into account.

Straight Match—used when design elements are arranged in a repeat pattern that should align on successive strips. The top of each wallcovering strip will start at the same ceiling line. It is most common that these patterns dictate a Straight Hang, although there are designs created for Reverse Hang applications.

Drop Match—some patterns are designed with elements that should align, but not in a straight across manner. There are several different types:

• Half Drop Match—each adjoining strip aligns halfway between the vertical pattern repeat (i.e., simply a straight match split in half). Every other strip will start at the same ceiling line, and the design elements will run in a diagonal direction. It takes three strips to repeat the vertical design. If the strips are numbered consecutively, the odd numbered strips (1, 3, 5, etc.) would be identical, and the even numbered strips (2, 4, 6, etc.) would match one another. Note: if marking strips, use a pencil to lightly number on the back, in the order in which they are to be hung.
  
  
• Multiple Drop Match—a match that takes four or more strips before the vertical design is repeated. This is similar to a half-drop match, except that it takes more strips before the pattern on the first strip is repeated.

Adhesives

There are several types of wallcovering adhesives, each formulated for specific applications and performance characteristics. Adhesives vary in level of wet-tack, solids, open-time, strippability, and ease of application. Other variables include low VOC levels and antimicrobial resistance. They are generally applied on the back of the wallcovering by a roller or pasting machine. The manufacturer’s installation instructions should always be consulted prior to an installation.

Cellulose Adhesives—pastes that possess the highest water content of those in general use (around 97%), and are the least tacky. They are usually packaged as a dry white powder, to be mixed with cold water, on the job. Cellulose adhesives are primarily intended for applying lightweight materials such as murals, grasscloths, paper-backed corks, and silks. They leave very little solids behind, and are not suitable for wallcoverings that require greater amounts of initial tack and holding power.

Clear Adhesives—pastes based on natural polymers such as wheat or cornstarch, or on synthetic polymers. Additives may include cellulose, biocides, and flow agents. Many clear adhesives are designated as "strippable," for use on bare sheetrock to allow for future stripping. They are for all-purpose use with the widest variety of wallcoverings, ranging from very light vinyl to heavy types. The water content is usually in the 60-70% range. Clear adhesives are generally considered to allow for more open-time and are easier to clean up than clay-based adhesives.

Clay Adhesives—like clear adhesives, these pastes are starched based, but clay is added as a filler to increase the wet-tack and level of solids. They are considered to have a higher level of wet-tack and are more difficult to clean up compared to clear adhesives. Developed for hanging fabric-backed, commercial vinyls and wallcoverings that require superior tack, they consist of clay, dextrin, and small amounts of cellulose, biocides and other additives. There is a machine-grade clay premix that includes glycerin for use in pasting machines. Clay-based adhesives have the lowest water content (40-50%) of any paste in general use.

Vinyl-Over-Vinyl (VOV)—adhesive intended for commercial applications where an existing vinyl wallcovering will be covered with new vinyl wallcovering, or for Mylar and foil materials. VOV is extremely tacky and is sometimes used in special problem installations that demand an especially tenacious paste. Note: Hanging vinyl over existing vinyl wallcovering may significantly increase flammability and smoke generation, and may not comply with flammability standards.

Mold and Mildew

Although wallcovering is often cited in connection with mold and mildew growth, in virtually all cases it is due to excessive moisture. To prevent wallcovering discoloration or wall deterioration caused by mold and mildew, the source of the moisture must be identified and eliminated. In unusual cases where moisture or moisture infiltration from the wall cavity cannot be eliminated or sufficiently reduced, wallcoverings with higher permeability ratings should be considered.

Mold and mildew growth on wallcoverings is a common problem in humid, coastal regions, often occurring when moisture penetrates an outside wall and gets trapped behind non-breathable wallcoverings. Drastic changes in interior temperature and humidity conditioning, such as in school or hotel rooms that are not conditioned when vacant, can also cause condensation on the backside of non-breathable wallcoverings.

The four primary factors that influence moisture levels in buildings are:

1. Building tightness, which does not allow moisture to escape to the outdoors;
2. Liquid water infiltration from outside as a result of a leaky building envelope or structural failure;
3. Moisture condensation on cold surfaces of building materials or components, which originates from water vapor inside or outside the building;
4. Moisture generated within the building by the occupant and the occupant’s activity.

Several ways to reduce the likelihood of mold and mildew growth include:

• Using airflow and vapor retarders in exterior walls to keep them dry. It is best to analyze an entire wall assembly to ensure that condensation during heating and cooling cycles will not occur.

• Avoiding multiple layers of wallcoverings. Since existing wallcoverings, backings, or adhesives may be contaminated, applying a second layer of wallcovering creates the potential for problems due to multiple vapor retarders.

• Requiring hydrophobic construction materials with low moisture content to ensure that an area is enclosed, dry, and conditioned before interior finishes are applied.

• Providing positive air pressure to reduce moisture infiltration.

• Exhausting high-moisture areas such as shower rooms directly to the outside.

• Balancing HVAC systems for ventilation and maintain constant temperature and low humidity.

• Using vapor permeable wallcoverings that are breathable.

The control of moisture vapor and its relationship to different types of wallcovering constructions should be communicated to specifiers, installers, architects and property owners.

Permeability

Successful use of vinyl wallcoverings requires having building walls that are not subject to moisture accumulation. An important benefit of conventional vinyl wallcoverings, in terms of durability, cleanability, and wall protection, is that it has little or no moisture permeability, which protects the wall from moisture penetration. However, if deficiencies in the design, construction, or maintenance of a building allow liquid or vapor moisture to accumulate in a wall or wall cavity, vinyl wallcoverings can act as a vapor barrier, restricting the escape of moisture and increasing the risk of mold growth and other building damage.

Before installing any wallcovering, moisture and sources of moisture accumulation must be corrected. Mold inhibitors contained in vinyl, adhesives, and primers used for wallcoverings will not prevent mold growth if moisture is allowed to accumulate in a wall. However, the permeability of conventional vinyl wallcoverings can be increased by high quality perforation, or microventing. Once perforated and properly installed on a permeable wall surface that is properly maintained, vinyl wallcovering will have increased permeability.

A permeability rating is a measure of the amount of water vapor (moisture) that can pass through a specified material in a certain amount of time. The measure and degree of permeability is expressed in units referred to as "perms." Materials with high perm levels will allow more moisture or water vapor to pass through than those with lower perm values. Although there is no officially sanctioned test procedure, the ASTM E-96 is used by many wallcovering companies to measure permeability.

NSF/ANSI 342

In 2008, the Wallcovering Association (WA) began a journey towards the development of a comprehensive sustainability standard for wallcovering products. Recognizing the ever-changing business climate that environmental issues raise, the wallcovering industry sought to address the multitude of issues brought up by its customers through organizations like the United States Green Building Council (USGBC).

The WA Sustainability Standard was developed through the American National Standards Institute (ANSI) along with industry, user groups, and public health representatives involved in the standard writing process. The WA partnered with NSF International, the accredited public health and safety organization, to build a consensus-based standard.

NSF is a third-party certification body that tests and certifies products to verify that they meet established standards.

 NSF/ANSI 342 evaluates all types of wallcovering products across their entire life cycle, from raw material extraction through end of life disposal. The standard allows for transparency into the performance of individual products, their manufacturers, and their distributors. A point system is used to evaluate products in six key areas:

1. Product Design
2. Product Manufacturing
3. Long-Term Value
4. End-of-Life Management
5. Corporate Governance
6. Innovation

Unique to this multi-attribute standard is the requirement that both a qualified manufacturer and distributor have been certified for a specific product. Each party may gain points in each of the established six categories. The total points gained by both determine if the product certifies, and to what level: Compliant, Silver, Gold, or Platinum. NSF/ANSI 342 allows specifiers to quickly and easily identify wallcoverings that meet the sustainability standard, and to make an informed decision. As of January 2015, Wolf-Gordon has been certified as an NSF/ANSI 342 Distributor.