Decorative plastic laminate

Decorative plastic laminate is made of kraft paper infused with a synthetic resin. It is cured under heat and pressure to make a single, homogenous piece. The first laminates were created with phenolic resins and was used in electrical and the automotive industry. In the mid 1920s, decorative laminates were being used as countertops, tables, splashboards, paneling, and ornamental design.

History
Laminates were first developed in the early 1900s by Leo Baekeland. Baekeland injected fibrous sheets with a phenol formaldehyde resin. The General Bakelite Company sold resin to companies that produced a phenolic laminate for electrical purposes by impregnating a heavy canvas with the Bakelite resin. Daniel O’Conor and Herbet Faber found a way to turn the laminate into sheet forms. The Formica Insulation Company of Cincinnati soon opened. The name “formica” is formed by the phrase “for mica” implying that the laminate was substituting for mica as an electrical insulator. When Baekeland’s patent expired, a flood of plastic laminates entered the market. By the 1920s, radio cabinets were the first to boast a decorative laminate. Because of the dark color of phenol formaldehyde, only dark colors were initially offered. Any attempt to change the color was usually messy and a failure as the dye would rub off. Lithographed wood grain laminates could be applied but an opaque sheet was used as a barrier to block out the dark interior. Plastic laminates could later be created colorless in 1927 by the introduction of lighter colored laminates. Urea-formaldehyde resins had a tendency to warp and absorb water and were more expensive than phenol resins. Both of these resins were not good conductors and if heated or a lit cigarette was placed on them, they would singe. Formica later incorporated thin aluminum foil between the surface of the laminate and the core. More durable products were later created with melamine resins. Combining melamine with formaldehyde, the laminate could resist abrasion heat and moisture and the range of colors was significantly greater. While melamine had several advantages, it was incapable of phasing out phenolic resins because of its expensive price tag. Melamine was traditionally used as a surface layer for other laminates, either colored for decorative purposes of clear for protection. 1948 introduced a low-pressure polyester laminate that was flexible and could be curved or odd-shaped to match components. Decorative uses included light fixtures or wall panels. Post forming grades of phenolic laminates were also popular in flat sheets that were to be reheated and formed into splash back or counter edges. During World War II, experimentation in the plastic industry generated new technologies and ideas. Industrial grade laminates could be produced for defense purposes. The use of laminate increased dramatically in the postwar period, being used in cinemas, kitchens, diners, and in present time, flooring.

Manufacturing Process
To begin the process, kraft paper must be cleaned for proper bonding. It then passes through a bath of liquid resin and heated to vaporize solvents. The sheets are cut and stacked in layers. With 300 degrees of heat and 2,000 pounds of pressure, chemical reactions in the resin are forced to take place as they are mashed by a hydraulic press. The heat causes a reaction in the resin, forcing the polymer molecules to fuse the sheets together until a solid piece is formed. It is then cooled while under pressure by water or placing the laminate in an annealing oven. Press plates are used to apply a gloss or matter surface. High gloss finishes are achieved curing the material against a burnished metal plate. To achieve a more satin finish, the plate under goes the same process but is buffed at the end. Decoration can be achieved by applying a sheet on the top, that will carry the design over the other layers of material and curing the entire unit. Designs can be etched into the surface by means of a cylindrical copper plate that will place the pattern on a roll of paper. Decorative inlays can be built up in a surface by cutting strips of materials in the form of the pattern and laying them on the sheet. Even with new technology, the process has not changed significantly, except for the development of new resins and some filler sheets. Fillers include the following types of paper: kraft, alpha, cotton fabric, asbestos felt, or fiberglass.

Uses and Installation
Because decorative laminates can range in thickness, they can be used for countertops to self-supporting panels and partitions Sheets that will act as veneers can be attached to plywood or sheet metal by casein or resin glues or bonding cements. Exterior laminates may be attached by screws. As materials modernized, laminates grew in popularity for theaters, diners, and stores. Storefronts, paneling and wainscoting, countertops, and furniture, as well as illuminated sign displays were all possible and popular used for plastic laminates. The use of laminates is so diverse that the president of Formica, Herbert Faber (1930s), used laminates to construct an entire building. He replaced windows, light fixtures, walls, and the shower curtains with his laminate product. The plastic laminate has also been used in ocean liners like the Queen Mary, but mostly for decorative purposes.

Conservation
The laminate’s performance depended heavily on its ability to act as a single, homogenous unit. The degree of polymerization, filler materials, and plasticizing resin would affect the materials physical appearance and its strength or durability. Decorative laminates are hard and durable but may be subject to deterioration in normal operating conditions. Failure will occur if the plastic’s polymer chain is broken, whether by extreme sunlight, moisture, chemicals, or stress. Deformation is possible when they laminate is subject to any of these conditions for extended periods of time.

Deterioration
Chemical and physical changes are expected to occur in plastics when they have been exposed to high heat or cold. Temperatures that remain elevated will cause the bonds of the polymerization between the resin and laminate’s base to disintegrate. Heat will dry out moisture, solvents, or plasticizers, as well as change the material’s molecular makeup. When the temperature increases, the laminate loses its resistance, making it more susceptible to other degradation. Freezing temperatures cause the laminate to become brittle. Heat cab cause shrinkage and may result in blistering, delamination, or cracking. Exposing the laminate to water for long periods can also cause problems. Cut edges are more susceptible to water absorption which can result in dimensions. With high humidity, laminates will swell and then dry out and become brittle as the humidity ceases which will leave unsightly cracks, peeling, or warping. Light can also affect the speed of deterioration in plastic laminates. Ultraviolet lights are the most destructive but sunlight can also cause extreme discoloration. Prolonged exposure to ultraviolet light can cause the phenolic resin to turn dark yellow but sunlight will cause the plastic to fade and have a matte appearance.

Laminates are likely to deform from impact because the internal structure will be affected. Tension and compression laminate will deform. The amount of tension and compression that will affect the laminate depends strongly on the direction of the load in relation to the layers of the material. All stresses can cause some deformation but most recover from the deformation quickly due to the elasticity of the product. Surface fractures or ply separation is an obvious sign of impact failure.

The plastic laminate is usually chemically immobile but exposing it to certain solvents or cleaners can cause extreme deterioration. Hydrochloric acid, sodium hydroxide, hydrogen peroxide, acetone, and sulfuric acid greatly affect the plastic laminate. Easily identifiable signs of damage include discoloration, warping, or shrinkage. Adhesives can also fail due to the deterioration of the laminated surface. They are highly resistant to heat and moisture but the bond can be affected by the material preparation before the adhesives and assembly conditions. Several other aspects that would affect the adhesives quality include the preparation of the surface, the amount of coats, the drying process and the application of pressure, open drying time, and room temperature while the material cures. There is no serious threat from fungi or insects unless the surface has been cut deeply or broken.

Detection of deterioration and the cause for it is the most important step in saving the plastic laminate. The piece should be examined regularly and their condition noted. Changes in color hazing, a more matte appearance on a once glossy surface, cracking, or delamination may be easy ways to spot deterioration. Nondestructive test should be done to establish what actions are necessary to prevent further cracking. Seams, laps, isolated porosity, leaks, or lack of fusion are other things to look for when inspecting a plastic laminate’s deterioration level. Applying a liquid penetrant over the surface should be the first step in identifying problem areas. After allowing for the penetrant to seep in, the product should be wiped away. A developed should be applied to draw the trapped penetrant out and stains the developer. The surface is then examined and failures in the laminate can be identified.

Conservation Techniques
Reducing the amount of contact a plastic laminate has with extreme temperatures and light will assist in conservation of the piece. Maintaining a temperature of 70 degrees Fahrenheit should limit thermal effects on laminate, while a level of humidity ranging between 20 to 80% should aid in the amount of moisture absorption. Also, reducing the exposure to light is a difficult but accomplishable technique to avoiding damage. Laminates should be cleaned periodically to reduce the amount of contaminants that may build up. Washing with a soft brush and warm water with a small quantity of non-ionic detergent should be the most aggressive cleaning needed for most plastic laminates. Rinsing the materials after cleaning is strongly suggested, being sure to use clean water and drying after with an absorbent material. On-site laminate repair is possible for slight surface issues (i.e. scratches) but can also be helpful in repairing more serious damage. Cellulose resin is used to fill in the damaged area. The resin is then recolored to match the existing materials.

Replacement
When replacing plastic laminate, the depreciated pieces are heated to break the adhesive bond. The base is inspected for sign or deterioration and should be replaced if such evidence is found. The base is then cleaned and a bonding cement is applied evenly and allowed to dry. After the bottom adhesive dries, another coat is applied to the bottom of the laminate and the base. Wood clamps are used to hold the pieces in place and covering the area should take place immediately to reduce the risk of dust or dirt while the glue sets. When replacing historic laminate, matching the patterns or colors may prove difficult. Boomerang and wood patterns are now readily available, which was a popular style when laminate was first introduced. Integrating new panels into the old style may be an easier way to replace historic plastic laminate. Adding new patterns or even solid colors that compliment the pattern was be an easy solution. The biggest problem one may encounter when matching historic and new laminate is the amount of fade the historic laminate may endure and the inability to recreate this wear pattern on the newer laminate.