The Vinyl Wallcovering Handbook
October 13th, 2009
VINYL WALLCOVERING HANDBOOK
by Alan Benjamin
INTRODUCTION
The walls of any given room represent the largest single area of eye contact in that room. Hence, if a decorative atmosphere is desired for that room, the walls play a very major part. Professional decorators have known for years the asset that wallcovering can be in establishing a mood or feeling as one walks into a room for the first time. Evidence of this fact is reflected by the time, energy, and money invested in the real estate field when selling homes or condominiums from models.
As you will see, people of all ages and backgrounds, since the beginning of time, have made efforts at decorating the wall space that surrounds them. In the following pages, I will endeavor to bar out some of the highlights of this decorative product from the past to the present. This text is designed as an aid in comprehending the many facets of todayÌs product.
HISTORY OF WALLCOVERING
Details are not available; yet archeologists have told us that cave drawings date back several thousand years B.C. We will never be sure of exactly why our ancient ancestors chose to draw images in their living environment. The two major theories concerning the reason behind these graphics are explained as wish fulfillment and aesthetics or art. Although this does not resemble wallpaper as we know it today, it does signify manÌs earliest desire to decorate his surroundings.
Proof does exist that the Chinese hand painted landscapes and birds on rice paper as early as 200 B.C. It took, however, until the 16th Century before these oriental prints were imported to Europe. Some of the delay was caused by the predominance of hanging textiles over walls. During this period, the affluent homes were built of stone, so the practicality of textile hangings was used to keep down the cold and dampness of these castles. Wallpaper was soon to become the Ïpoor manÌs tapestry,’ an imitation of the expensive textiles used in royal households.
The demand for wallpaper grew rapidly and by 1599 a recognized guild, known as the ÏDominotiers’ was established in France. The Dominotiers were also responsible for introducing the process of using wood blocks with the design cut into the surface to be used for printing.
The development of a repeating pattern was introduced by a Frenchman, Jean Papillon, in 1675. He is said to be the real inventor of wallpaper as we know it today, by advancing our technique to match a repeat on all sides, while still utilizing the wooden blocks.
By the early part of the 18th Century, progress had expanded into strips, rather than small sheets corresponding to the size of the wood blocks. The designs and the quality intensified with the best artists going into this new field. (*NOTE) It was, however, the following century, the mid-1800Ìs, that man fabricated a machine capable of printing for him, rather than printing by hand. The quality was severely neglected and wallpaper consumption was being weighed as a major factor for the first time, rather than an art form.
The next development was to have a long lasting impact on the future of wallcovering. In 1921, the first step was taken by the Standard Coated Company (Sanitas) in producing a coated linseed oil product (oil cloth). This initial phase of breaking away from paper as the principal stock on which to print, was a step which would never be reversed, and it was only a matter of time before the vinyl of today took over. That is not to say, however, that paper is no longer used in our product. We have paper today in both the low and high-end markets, as simply a paper product. Paper is also used as one of several backings for vinyl sheeting, grass cloth, etc., and as the foundation of many vinyl coated products.
(*NOTE) If you are interested in visiting this countryÌs historical landmarks, there are breathtaking examples of hand painted strips in Williamsburg, Virginia. The restored area of Colonial Williamsburg, protected by our National Park Service, has several rooms in which original wallpaper of the 18th Century was tediously removed from locations in England and brought over to this country. It is hung in the GovernorÌs Mansion restoration for our viewing enjoyment.
This brings my outline up to date. Here again, I wish not to present these facts for any other purpose than to bear out manÌs consistent urge to decorate his walls. In closing, we should all be thankful for the improvements made from generation to generation, which allows us the know how to make superior quality product of today. We are involved in a terribly exciting field that is ever changing and always challenging.
THE MANUFACTURE OF VINYL
PVC is the common abbreviation for polyvinyl chloride, one member of a large class of polymers called vinyls. Vinyl constitutes one of the most versatile groups of plastics, which range in form from soft flexible sheeting to hard, rigid structures, either of which may be solid or cellular (foam). PVC and its derivatives are the second highest tonnage plastic in the world.
The earliest application of PVC, pre-World War II, was used to coat the interiors of beer cans. However, greater utilization soon followed at the time of the war, when PVC was used as a replacement for rubber sheeting and electrical insulation. This marked the onset of an avalanche of products in the years that followed.
I am not trying to influence anyone into becoming a chemist; rather, I will attempt to explain, in laymanÌs terms, what goes into the vinyl product.
IÌll start at the point of vinyl chloride gas, which is the building block. The process begins with this vinyl chloride gas being brought to us by rail tank cars. This gas is unloaded under pressure by way of a closed link underground storage system. The simplest purpose of this next step is to link together vinyl chloride monomers in succession to form a chain, called polymerization. Through the use of heat reactors, this gas is subjected to an increasing processing temperature, until the polymerization level is reached. This chain linking or branching, as it is called, can be controlled by the temperature at which the gas is maintained. Lower temperatures lead to faster rates of polymerization, less branching and higher molecular weight chains and vice versa with higher temperatures. This procedure provides us with our PVC resin, now a solid granular substance, similar in appearance to popcorn.
From this point of resin production, we then proceed to the compounding area. It is here that certain additives are introduced, once it is determined what the specific end product characteristics are to be. This compounding or blending is what you may hear the plant personnel refer to as Ïmixing a cake.’ By use of large tumbling barrel blenders, the resin is mixed with any number of additives, under constant agitation and heat resulting in a Ïdry blend.’
The following are additives and a brief summary of their purpose:
Plasticizers Á low molecular weight solids, mainly organic salts used to add flexibility and softness.
Heat Stabilizers Á to prevent discoloration during processing.
Pigments Á we grind our own for purity reasons. It resists bleeding and weathering better than dyes.
Fillers Á although they do reduce the cost of formulation, they are included for the advantages they represent. The improved properties they add are resistance to ultraviolet light, better dent resistance, increased hardness, gloss control, improved dry blending, reduced plate out and resistance to deformation under load at high temperatures.
Processing Aids Á promotes fusion, reduces surface gloss, improves roll release on calendars and enables processing at lower temperatures.
Impact Modifiers Á added to protect from brittle fracture.
Lubricants Á these fall into two categories:
External: reduce the external friction of melting with the surfaces of processing machinery. They are incompatible with the resins at processing temperatures and thereby readily form a lubricating surface layer.
Internal: operate by lowering the interparticle and intermolecular friction during processing, thereby reducing melt viscosity and frictional heat buildup.
Light Stabilizers Á work in conjunction with the pigment and heat stabilizers to absorb ultraviolet light and dissipate it harmlessly as heat.
Flame Retardants Á since PVC contains a considerable level of chlorine, it is self-extinguishing by itself. Even compounds containing a 25 percent concentration of flammable plasticizers remain fairly resistant to burning, as defined by present flammability tests. However, any compound with a higher percentage of flammable plasticizer would require the addition of flame-retardants.
Antistatic Agent Á improves the electrical conductivity.
Antioxidants Á protection in high temperature applications like electrical wire insulation.
Fungicides Á although vinyl resins themselves are not subject to attack by microorganisms, some of the additives of the compounding may be vulnerable.
This is only a brief look at what may be introduced in varying quantities during blending. From here, our Ïflour-like’ mixture is sent to the fluxing machine, which melts the compound into a liquid form. The heated material (approximately 350 degrees) can be fed directly to the processing machine (calender) or pelletized and cooled for later use, as in injection molding. The calender is a piece of machinery which, using pressure, forces the heated compound into film sheeting. The calender operation is capable of producing vinyl film ranging in thickness from 2 gauge to 30 gauge and in widths up to 84 inches.
From a substance that gained popularity due to its rubber-like properties, we have literally surrounded ourselves with vinyl. Deeply entrenched in such fields as flooring, wearing apparel, packaging, automotive and so on (not to mention wallcovering), the full potential of PVC has not yet been reached.
HOW VINYL RELATES TO THE WALLCOVERING INDUSTRY
There are two main factors that dictate the use of vinyl wallcovering instead of paint. They are the aesthetics and the economy a vinyl product offers.
The beauty of a vinyl wallcovering is the result of the proper combination of color, texture and embossing. To this we compliment our product by coordinating several sheers designed to work, tone on tone, with the original sheet. This, in itself, surpasses anything attainable with paint.
The second factor of economy is a little more detailed. Such things as: durability, life cycle vs. repainting, maintenance (washable, stain resistance) and safety must all be observed.
Durability Á vinyl, by its nature, resists scuff marks, staining and fading. These benefits must then be added to the protection against chipping, cracking and abrasion.
Service Life Á Routine area cleaning of dirt and grime must be performed periodically on a painted surface. Heavy traffic areas require more time to wash stains and repair chipped, cracked surfaces. Although conditions vary, the average life expectancy of a paint system is three years.
In comparison, the vinyl wallcovering only needs occasional spot cleaning. The superior ease with which it cleans is enhanced by its resistance to soiling and scuffing. Also to be considered is the down time required to refurbish. In so many instances the loss of revenue is substantial when rooms are being redecorated. Hanging vinyl can keep your down time to a minimum, as well as add years between refurbishing. The average life span of vinyl wallcovering is nine to ten years.
Maintenance: Most stains, scuffs, and dirty areas are easily cleaned with mild detergent and warm water. Any area of extreme wear and tear can have the wallcovering treated with an additional Tedlar (one half mil polyvinyl fluoride film laminate) coating, which will stand up against the strongest detergent or harshest solvent.
Safety : All of our wallcovering has been tested and found to be in accordance with the provisions of ASTM Designation E84-70 ÏStandard Method of Test for Surface Burning Characteristics of Building Materials.’ These tests have been performed and certified by the Southwest Research Institute.
PRINCIPLES OF PRINTING TECHNIQUES
Modern wallcoverings are produced by three methods of printing: roller or surface printing, rotogravure, and silk screening. These methods can be best understood by realizing the contact point at which the ink meets the material to be printed. Roller printing is when the inks are applied from a raised position on the roller. In rotogravure, the inks come in contact with the material from a sunken or Ïhollowed’ area, and in screen printing the inks merely lay flat across the surface.
Outside the wallcovering industry, printing methods do parallel our manufacturing techniques. For example, rotogravure or intaglio, as it is called, is the same method used to prints our stamps and currency. The cousin, so to speak, of roller printing is the letter press, or printing from a raised surface, which works essentially the same as an ordinary rubber stamp. Lastly, the differences with screen-printing are greater. The only common trait that screen-printing has with lithography is that they are both printed on smooth surfaces.
In screening, your image is going from a positive to a positive, and in litho your image is going from a positive to a negative to a positive.
ROTOGRAVURE PRINTING
In rotogravure printing, each color is represented by an engraved print cylinder, an ink pan (a fountain), a doctor blade and an impression roll. The roller, which is the key to gravure printing, has the design etched into it. The depth of the etching controls the amount of ink transferred to the web (material). The deeper the cut, the deeper the color. Very clear, beautiful graduations in color tone are the result. By etching different depths into the roller, one roller can produce many values of the same color. As the print roller is rotated, it passes through the ink pan. As it continues to turn, the doctor blade wipes the cylinder clean, except in the etched areas of design. The rotating cylinder is then pressed against the material by the impression roller and the inks are freed out of the design and onto the material.
ROTOGRAVURE STYLES OF PRESS EQUIPMENT
There are three types of roto presses; the u-shape, the stack, and the in-line. The u-shape press is called this because the print heads are placed in a u-shaped fashion, usually in a pit lower than the balance of the equipment. The number of desired colors are printed, and the material moves across the top in a central drying furnace. The inks are dry by the time they reach the other end. At this point, we laminate our substrate to the printed film and the material is sent through a series of heater and chiller rollers to set the bond. We also have the option to emboss or not, depending on the desired effect. We print and then laminate; yet there are many other manufacturers that do the opposite, or print pre-laminated goods.
With the stack machine the print cylinders are stacked one on top of each other. The material is printed, thread back into a vertical dryer and back out to the stack for the next print head. After all the colors are printed, the material moves across the top in a horizontal final dryer (approximately 140 degrees F) to rewind the sections. As with the other two styles, the tack has a control panel, which insures proper lateral and vertical registration and uniform color only. The stack requires the least amount of floor space of the three.
The third and final type of machine, the in-line, has the print stations placed one in front of the other or Ïin-line.’ This machine will require the greatest amount of area. The principle of gravure printing is the same in all cases, regardless of where the ink fountains are positioned. More importantly, the wallcovering is of the same quality, whether run on a stack, a u-shape, or in-line.
SCREEN PRINTING
Screen prints can be made by one of three methods; entirely by hand, partly by hand and partly by machine, or fully automatic. All three methods employ the same printing principles with each color being applied by a screen and a squeegee. When screen-printing was first introduced, the screens were all made of silk. However, todayÌs screens are made from polyester, rayon or nylon, even though they may be referred to as silkscreen. The material is woven in a pattern, very similar to a cheesecloth design with thousands of openings.
A screen is made for each color in the design and it is done by a photographic development process. The colors are separated in design and a clear plastic film is placed over each separate color. The siding is then reproduced on the clear plastic film. The designed film is then placed over a light source (usually consisting of several six foot fluorescent lights). The screen is coated with a light sensitive solution and placed on top of the design, so now there are three layers: the light source a the bottom, the clear film with the design in black, and the treated screen is on the top. When the light source is turned on, the light passes thorough the clear film, except where it is blocked by the design. The illumination hardens the light sensitive material where there is no design. The area on top of the design does not harden and it is then washed off to form a usable screen.
HAND PRINTING
On hand screen-printing, each color is represented by the screen and the squeegee, which looks very much like and oversized windshield wiper. The ink is applied to one side of the screen and spread evenly across the screen by the squeegee. By this action, the ink is forced through the pores of the screen and transferred to the surface of the wallcovering. The printing is done by moving the screen from one position on the table to the next, and skipping the alternate repeat to allow the inks to dry.
FLAT BED SCREENING
The flat bed screen-printing method is an extension of hand screening. Instead of an individual printing the material, the machine using the same principle handles the entire operation. Each color is represented by a silkscreen flood bar, and a squeegee. The screen is elevated above the material and the ink is trapped on the right side, between the flood bar and the squeegee blade. The flood bare and the squeegee then move from right to left, spreading the ink across the screen. When they reach the left side of the screen, the screen is lowered onto the material. The squeegee moves from left to right, applying pressure downward. The inks are forced through the tiny holes of the design area onto the material. After each screen is a horizontal heater that can be angled to increase or decrease your drying temperature. The material moves along under the screens on a large conveyor, called the blanket. Embossing is not a capability of this type of equipment, yet the roll-up reels can be trimmed by slitter blades, if desired.
The benefit of screen print over a rotary machine print is the heavy inlay of ink that you are capable of getting.
GLOSSARY
Companion Papers A set of two or more papers designed and colored to be used together in the same or adjoining areas.
Correlated Describes different types of merchandise systematically related in color and design, such as wallcovering with a harmonizing fabric.
Double Cutting A procedure of trimming done on the wall, rather than on a table.
Procedure: Overlap one strip on top of the adjoining strip by the amount to be trimmed. Firmly hold a straight edge over the seam at the point that permits the design to match from sheet to sheet. Cut through both overlapped seams at once, holding the edge of a new razor as parallel to the material as possible. Remove excess inner and outer trim and carefully push edges together.
Drop Match Think of it as a straight across match. However, instead of the match point being found directly horizontal across the sheet, it will be found on the other side, at the point half the distance from where the straight across match would be. (For cutting purposes, every other sheet will be identical.)
Embossing The raised effect created when metal rollers impress a design into the back of a wallcovering.
Flock Wallcovering imitating the cut velvet look. The pattern is printed in glue or varnish and the flock (finely chopped fibers of rayon or nylon) is shaken across the top.
Foil A very thin sheet of flexible metal, usually on a paper, but sometimes on a fabric substrate.
Grass Cloth Originally a hand made product imported from the Orient that is made by gluing woven native grasses on a paper backing.
Lamination The process of building up in thin layers. Using heat and pressure, the adhesive bonds together several layers into one product.
Lining Paper A plain paper applied before wallcovering to assure a smoother surface and better adhesion.
Match The art of hanging strips of wallcovering so that the design will be in correct relation to the preceding strip.
Random Match The simplest type, the pattern will match no matter where one strip is placed in relation to next. Usually all over textures, stripes, grass cloths, etc. are random match.
Register The guiding process that assures each color will fall in the proper place when applying multiple colors.
Repeat The distance from the center of one motif of a pattern to the center of the next.
Runs ManufacturerÌs term applied to the number of times an individual sheet is produced and repeated. Run numbers also indicate the production of material all under one color combination.
Selvage The edge of a roll of wallcovering, either trimmed off at the mill, or left on with trim marks for the paperhanger to remove at the time of installation (usually found in handprints).
Size A sealer used to prepare the wall surface before the wallcovering is applied.
Standard Roll Wallcovering is measured to contain approximately 36 square feet of material. However, the widths may vary, but the square footage remains the same.
A single roll, 20 1/2′ wide by approximately 7 yards in length.
A single roll, 24′ wide by approximately 6 yards in length.
A single roll, 28′ wide by approximately 5 yards in length.
A single roll, 36′ wide by approximately 4 yards in length.
Straight Match This is one in which any pattern has its match (or counterpoint) directly across the sheet. This type of pattern will show itself around the room exactly on the same horizontal line.
Tedlar This is one half mil polyvinyl fluoride film which is factory laminated to a vinyl wallcovering to provide exceptional protection against staining, scuffing, etc. (usually found in hospitals and schools).
Vinyl For the manufacturing of wallcovering, vinyl can be one of two types, either flexible film sheeting or liquid to be applied as a coating.
