Linoleum

Linoleum is derived from the Latin terms meaning flax (linum) and oil (oleum). Frederick Walton invented linoleum in 1863. Linoleum is made of oxidized linseed oil and ground cork or wood flour calendered into sheets with a burlap backing. Linoleum was a popular choice for residential and commercial  buildings from the 1860s through the 1940s. It comes in several thicknesses and countless patterns. Linoleum was idealized because of its water resistance, sanitation level, and noise-reduction properties.

History
Walton noticed a leathery skin developing on the top of paint that had been left uncovered too long. He thought this linseed oil could contribute to the manufacturing of waterproof products. In 1860, he patented a process for producing oxidized linseed oil (linoxyn). Three years later, Walton received a patent for “Improvement of the Manufacture of a Wax Cloth for Floors”, which would later become linoleum. Walton’s linoleum ingredients from 1863 are similar to those found in today’s linoleum. Linoleum was initially produced by Walton under the name Walton, Taylor and Company in England in 1864. By the next year, the name had changed to the Linoleum Manufacturing Company. In 1872, Walton and the Joseph Wild Company began the American Linoleum Manufacturing Company in New York. In 1886, Michael Nairn and Company of Scotland started a linoleum branch in New Jersey. The company became associated with the Dominion Oilcloth and Linoleum Company in Montreal and the Congoleum Company in the United States. The first installed America-built linoleum calender was installed in the George W. Blabon Company of Philadelphia in Nicetown, Pennsylvania. Armstrong Cork Company began a linoleum manufacturing plant in 1908, branching from their cork stopper business. The linoleum business was more prevalent in Europe in the beginning, finding the highest popularity level in Great Britain. Around the time Armstrong began linoleum flooring, the market was saturated with companies. There were seven companies in the United States while English and German manufacturers were trying to compete in the market as well.

Armstrong’s advertising and marketing techniques helped to launch linoleum into the spotlight. Armstrong began advertising in trade papers, sample books, and supplying explanatory literature to suppliers. Linoleum was initially used for commercial and residential utilitarian purposes, often being found in kitchens and bathrooms for sanitation purposes. Newer designs were made in an effort to make linoleum an acceptable flooring material in living and dining rooms. Frank Parsons was hired by Armstrong. Parson, who was known for his home decoration abilities, was hired to produce a book showing linoleum being used decoratively in every room of a house.

Linoleum was well known for its sanitary, sound-, and heat-insulating qualities thought these could also prove to be problematic. Resiliency and insulating qualities came from ground cork and wood flour. Cork was better for these purposes but in order to create the desired shade, significant amounts of white pigment were necessary to overcome the dark brown. With the addition of the white pigment, the effect of cork was diminished. Wood flour was lighter than but not as resilient as cork. Natural and brown-hued linoleum, for these reasons, prove to be the most resilient. Linseed oil, which was added to make the linoleum water resistant, began as a yellow or light brown color but had a tendency to darken over time. Pure white, rich blue and purple linoleum, therefore, were impossible to manufacture.

Originally, linoleum patterns were painted on top of solid color linoleum because the process to create patterns with different colors of linoleum had not been discovered. Technological advances provided means to produce a variety of inlaid linoleum patterns. These new types of linoleum were identifiable by the designs' integration with the materials during manufacturing process.

Manufacturing Process
Linoleum was first manufactured by spraying small quantities of linseed oil onto this cotton clothes called scrim. The material was then allowed to dry in a heated environment until the linseed oil buildup reached roughly one inch or more. During the boiling and spraying process, oxygen was absorbed and created linoxyn. The sheets, or skins, were taken down, ground up, put into pans, and heated until the pieces softened. The addition of pine rosin and kauri gum followed before the mixture was cooled and ground again. The product of this was called linoleum cement. Binding medium was then added into linoleum cement s well as some remaining ingredients.

Ground cork or wood flour, whiting, and pigment were added to the linoleum cement mixture and then pressed into a sheet by heated rollers of a calender. The sheet was then pressed by more rollers onto a canvas backing that was coated by a layer of paint (usually red oxide). The product was then placed in steam-heated rooms, where it would oxidize and polymerize over the next three weeks. The material left the stoves as a hard, leathery sheet. Linoleum was then treated with polish, wax, or lacquer to improve soil resistance and provide a better finish.

The first major improvement to linoleum was the integration of design into the material in the manufacturing process. The first linoleums of this kind were marble, granite, and jaspé linoleums. Granites were developed in 1879 by adding linoleum cement granules to linoleum sheets before they passed through the calender. Partially mixing colored granules before calendaring would produce marble linoleum. Jaspé was created by making random colors run in blended streaks parallel to the length of the linoleum. Walton created a method for inlaying geometric designs just before the end of the 19th century.

Geometric designs were made by laying a long piece of linoleum on a long metal table. Stencils were laid across the top of the linoleum and colored cement granules were place in these stencils. The stencil was removed and the linoleum was run through the calender. As the granules heated up, they fused together and to the canvas backing, producing a sheet of linoleum with a design on resilient material, all of which were fully integrated. It was not uncommon for some of the colors to blend when they came into contact with another color. Encaustic tile was usually simulated on linoleum in this manner. In 1898 Walton opened a factory to produce straightline inlaid linoleum. A variety of unseasoned colored linoleum was cut with a machine that pressed specially shaped pattern blades into the linoleum sheets. Workers then assembled the patterns in a specific pattern in a process called piecing. The name straightline was developed to describe the sharp lines that separated the colored shapes, which distinguished it from molded inlaid linoleum. Embossing was also a popular technique used in designing linoleum. A texture could be created by subjecting calendered molded inlaid sheets to an embossing press. The embossing press had plates fitted to elements of the design, such as mortar line. The plates pressed the elements below the surface material to create a relief. Embossed molded inlaid linoleum soon became the most popular linoleum type after its introduction in 1926. These types of linoleum remained the most popular types of linoleum manufactured. Spatter linoleum was a variation of the standard linoleum types but was unique and recognizable. After World War II, Armstrong introduced black and white linoleums with multicolored spatters. This design style would grow to nearly 40 color combinations over the next 10 years.

Linoleum was always created to imitate other materials, usually natural materials. Linoleum was made to replicate wood planks and parquet. Strips of wood grain were often sold as borders for area rugs. Carpet designs could be replicated in both inlaid and printed linoleum. Linoleum was adapted to follow design trends. For instance, during the Art Deco period, linoleum commonly required production of distinctive linoleum designs that had never been created before that time.

While linoleum ruled the market between the world wars, it saw its downfall to vinyl tiles shortly after. Linoleum, or rather its felt-based linoleum cousin, is still found in households today. Felt-based linoleum products were first produced in 1910. This was a bitumen-impregnated felted paper that had a printed design. The most popular use of this material was the room-sized rug that was printed with a border and center design.

Uses and Installation
Linoleum can be broken into various product types. The two most popular ways to categorize linoleum is whether it is plan or inlaid and by gauge (thickness). Typical gauges were 0.250 inch battleship, 6 millimeter battleship (.235 inch-heavy), 0.187 inch battleship (medium), 0.142 inch battleship (light), and A, B, C, D and E gauge plain. Battleship gauges were the thickest and therefore took the longest to cure in the stoves. Battleship gauges differed from the A to E gauges because battleship was not backed. The 0.250 inch battleship gauge was ideal for office, stores, hospitals, banks, and battleship decks. Thinner gauges were used for lighter traffic areas or areas where cost was a factor. Battleship colors were limited to darker brown, grays, and greens. In A gauge, light grays, blues, and tans were available. This gauge took only four weeks to mature and was ideal for apartments or lightly trafficked office areas. B, C, and D gauges were often used in residential areas while the E gauge was created mainly for the automobile industry. More gauges were introduced later for both plain and inlaid linoleum.

Originally, linoleum was installed over subflooring. This type of installation proved problematic because of the expansion of wood subfloors which would cause the linoleum to buckle or crack. To solve this problem, the process of gluing a felted product to the floorboards was introduced. Thinner gauges of linoleum still showed problem areas from the wood flooring, even with thick layers of felt. Before installation, it was recommended to smooth the floor as much as possible. Pattern books and trade journals usually contained detailed directions for properly installing linoleum flooring. The application started with a linoleum paste being applied to the felt with 4 or 5 inches of the seams. The sheets were they lay with seams lapping. The linoleum was then cut through both layers in one stroke. The unpasted edges were then lifted and adhesive applied to the edges. The floor was then rolled thoroughly. Linoleum placed on top of felt was installed in the same manner.

Linoleum was often produced with specific rooms in mind for the end application. Straight-line linoleum was available in designs created specifically for children’s playrooms, often using a game board patterns made of brightly colored pieces. Custom designs were possible and many company took advantage of this opportunity by having their company name created for the centerpiece of their office decorating scheme.

Conservation
Linoleum is commonly found in some state of deterioration. Linoleum conservation should involve the analyzing of the deterioration and its cause. Intervention should be kept to a minimum. Test should be done to investigate all forms of intervention and specialists should be used when expertise is required.

Deterioration
Deterioration of linoleum occurs by wear, water, or chemical changes within the product. Wear commonly occurs from dirt in high traffic areas. Heavy furniture or high-heeled shoes can cause indentations and serious surface damage. If the worn areas have exposed backing, the burlap is likely to come in contact with water and cause water damage. In cases where the worn areas have not broken the surface, water can still cause individual pieces to separate and warp. Once exposed to water, the backing material may separate from the top layer. Moisture will degrade the wood flour and cause it to swell or curl at the edge. Cleaning solution should never contain alkalis as they will soften the linseed oil, destroy the cork filler material, and attack the paints of printed linoleum. Damage caused by alkalis will present as pits or severe abrasions. Concrete subflooring exposed to alkalis will cause the floor to deteriorate in a similar manner.

Aged linseed oil may change in chemical makeup, causing it to deteriorate. Linoleum is likely to become more brittle as the linseed oil continues to oxidize. Linoleum with a high proportion of wood flour or cork to linseed oil is more susceptible to deterioration in this manner. Linseed oil will also darken over time, especially in darker environments. Lighter colors may appear darker than when they were originally installed. The colors may also differ depending on the room they are in based on the exposure to ultraviolet rays, or daylight.

Conservation Techniques
The location and the setting of which linoleum is found are essential to finding a proper conservation approach. Deterioration caused by wear or neglect should be identified and the caused for this damage analyzed. Analyzing the light source may also help in determining the areas that are closest to the original color. Like previously states, intervention should be minimal. It is important to understand the type of linoleum that requires conservation and develop a plan carefully suited for that specific composition. Testing areas are ideal and a trained conservator may be necessary.

Some of the easiest conservation techniques require little effort. Redirecting foot traffic in a room by moving furniture or the addition of rubber cups under heavy furniture legs may be the easiest way to protect a linoleum floor. Mats may also be used to protect linoleum in places of heavy foot traffic. In cleaning, it is important to try to minimize stress on the floor while improving its appearance. Testing is suggested for different cleaning methods. Some manufacturers may recommend a mild soap that may have a pH that is too high for older floors. Mild non-ionic soap with a neutral pH is recommended but should also be tested. Prolonged exposure to water or cleaning agents can damage linoleum floors. Liquid bleaches are likely to lighten the colors while powdered cleansers will abrade the surface.

Producers often coated linoleums with a varnish or shellac. If the linoleum has been treated with one of these products, a small spot for testing is recommended. Turpentine will remove the varnish and could soften the surface paint. Shellac is likely to respond to denatured alcohol. When stripping layers of old wax, a stripper strong enough to dissolve the wax without dulling the finish is important. Alkaline-based strippers should be avoided. Solvent-based may be capable of cleaning the linoleum without cause much stress to the material. Newer water-based products are used because they are safer for both user and environment. Testing stripping solutions to an inconspicuous area is essential. If the backing material has separated from the top layer without the old adhesive or backing deteriorating, injecting adhesives into the opening and rolling with a heavy roller may solve the problem. Pieces that have come apart but are still in an acceptable condition can also be glued back together with a compatible adhesive. Consulting the manufacturing about the adhesives compatibility with the linoleum is suggested. Also, the subflooring material and atmospheric conditions should be assessed. Old adhesives must be removed from the linoleum and the subflooring by mechanical methods. Chemical removers can drive the adhesive material further into the linoleum or substrate. All adhesives should be removed until the primary surface, either the linoleum or substrate, is visible. Scarring the subfloor will give it a mechanical tooth and help the adhesive form a connection with the substrate. Mechanically scraping the adhesive off the linoleum can cause damage to the backing but should not prove problematic when the floor is going to be relayed. Linseed darkening can be reversed by exposing the linoleum to daylight or fluorescent lighting. Fluorescent lighting can lighten to linoleum back to almost its original color in just a few days. Continuous exposure to daylight can help maintain the lighter hues. Once the linoleum has been repaired or cleaned, a protective coating, like wax or polyurethane, is strongly suggested. Sweeping or dry mopping the floor regularly is suggested to remove the surface dust and dirt. The floor should be mopped with a small amount of non-ionic, pH neutral detergent and rinsed with clean water only when necessary.

Replacement
Replacement linoleum is difficult to find, making it important to conserve historic linoleum. If replacement is necessary, all removed pieces should be documented and saved. While flooring distributors may have some linoleum in stock, it can be brittle or darkened. Exposing over darkened pieces to ultraviolet light may be an easy way to lighten pieces to match existing floors. Europe still supplies new linoleum pieces and can be used to replicate some historic patterns. Geometric designs can be replicated by skilled cutters that may be able to produce custom, straight-line inlaid linoleum on site. In some instances, historic linoleum has been replicated using painting or silk-screening a pattern onto a solid piece of linoleum using acrylic paints. The blended line of molded inlaid linoleum may be difficult to replicate. It is suggested that applying the pattern and then blotting while the paint is still damp may produce a similar appearance. Granulation can be achieved by stippling two or more colors over each other. If a replacement cannot be found, epoxy filler with fine inert filler can be used. The amount of inert filler compared to organic binder in the patch should be as close as possible to the linoleum being patched. The patch can be painted with acrylic paint and covered with sealant when it is completely dried. Also, in-painting can be used to cover worn spots in printed linoleum.

Linoleum is the predecessor to vinyl flooring. Vinyl manufacturers may carry several patterns that were originally used in linoleum.

Standards and specifications

 * ASTM F2195 - 07 Standard Specification for Linoleum Floor Tile
 * ASTM F2034 - 08 Standard Specification for Sheet Linoleum Floor Covering
 * ASTM F-710 - Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring
 * ASTM F-1482 - Standard Practice for Installation and Preparation of Panel Type Underlayments to Receive Resilient Flooring
 * ASTM F-1869 - Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride
 * ASTM F-2170 - Test Method for Determining Relative Humidity in Concrete Floor Slabs Using In Situ Probes
 * ASTM F-2420 - Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement.
 * ACI 302.1R - Guide for Concrete Floor and Slab Construction 117R Standard Tolerances for Concrete Construction and Materials
 * Resilient Floor Covering Institute (RFCI) Recommended Work Practices for the Removal of Resilient Floor Coverings
 * MASTERSPEC Guide Spec Section 03300, “Cast-In-Place Concrete”