Decorative Laminates Overlays and Prefinished Panel Products
Decorative surfacing materials are often applied to wood product cores such as industrial particleboard, fiberboard, hardboard, etc. Terminology and definitions of these overlay products follow, broadly grouped as:
Medium Density Overlay (MDO)
Pressed resin impregnated paper overlays, highly resistant to moisture, applied to suitable cores for both interior and exterior uses. The seamless panel face and uniform density furnishes a sound base for opaque finishes and paint.
High Density Overlay (HDO)
A thermosetting phenolic resin impregnated, cellulose fiber overlay that provides a hard, smooth, uniformly textured surface of such character that further finishing is not necessary. Some evidence of underlying grain may appear.
Thermoplastic Sheet
Semi rigid sheet or roll stock extruded from a nonporous acrylic/polyvinyl chloride (PVC) alloy solid color throughout. Withstands high impact. Minor scratches and gouges are less conspicuous due to the solid color.
Vinyl Films
Polyvinyl chloride (PVC) film, either clear or solid color, used extensively for decorative vertical surfaces in mobile homes, recreational vehicles, commercial panels and movable walls. Some films are available with scuff resistant top coatings.
High Pressure Decorative Laminate (HPDL)
A standalone product that can be laminated onto a core as the face of a sheet product or directly onto a structure as a covering. Decorative laminate is produced in a one step process by fusing together, under heat and pressure, multiple layers of kraft paper saturated with phenolic resin, together with a layer of melamine saturated decorative paper.The assembly offers resistance to wear and many common stains and chemicals. Common uses include casework exteriors, countertops, and wall paneling
Helpful Tip
Some decorative laminates utilize a white background paper to achieve the high fidelity, contrast, and depth of color in their printed patterns, which leaves a white line at the exposed edges of the laminate and can be extremely noticeable in darker colors.
Low Pressure Decorative Laminate (LPDL)
Decorative thermally fused panels flat pressed from a thermoset polyester or melamine resin impregnated web. Most products are pre laminated to Industrial Particleboard or Medium Density Fiberboard cores when they arrive at the woodwork fabricator. Performance characteristics are similar to High Pressure decorative laminate except for the impact test. Thermally fused papers and foils are similar to that used in the manufacture of decorative laminate. Saturated with reactive resins and partially cured during manufacture to allow for storage and handling, the papers achieve final curing when they are hot press laminated to a core, providing a hard, permanent thermoset bond between the paper and the core.
Melamine Impregnated papers, the most common, are noted for their hardness, scratch resistance, and color stability
Polyester Impregnated papers are noted for their chemical, stain, water, and impact resistance; color clarity; and machinability
Common HPDL Types
In summary, these common decorative laminate types have the limitations of high-pressure decorative laminate:
They are for interior use only and will not be successfully used outdoors or under heavy exposure to the ultraviolet rays of the sun.
They should not be used as cutting surfaces, because knives and other sharp tools will readily deface the surface and lower its other performance capabilities.
They should not be exposed to caustic chemicals, such as drain and toilet bowl cleaners, which can permanently etch the surface.
While they offer outstanding heat resistance, exposure to constant heat from a curling iron, an electric skillet or coffee pot, for example can harm the surface and may cause it to delaminate, discolor or blister.
The basic types form the majority of applications of high-pressure decorative laminate in North America are:
General Purpose (HGS and HGL)
Used for most horizontal applications, such as desk tops and self-edged kitchen countertops, “HG” laminates offer durability, resistance to stains, and resistance to heat.
Vertical (VGS and VGL)
A slightly thinner material, “VG” laminates are produced for areas which will receive less wear and impact than typical horizontal materials. They are an excellent choice for cabinet doors, the sides of casework, primarily decorative display shelves and vertical panels.
Post-forming (HGP and VGP)
Specifically, for applications where a radiused surface is desirable, “P” laminates offer strong performance in both horizontal and vertical applications.A major advantage of formed surfaces on the exposed corners of casework and service counters is the edge’s resistance to chipping damage. Most chip damage occurs at sharp 90° corners. Surfaces are thermoformed under controlled temperature and pressure.
Cabinet Liner (CLS)
A thin vertical sheet, this type is designed for areas where the surface, which is not considered decorative, generally white or off white in color, but will need to withstand less wear, such as the inside surfaces of cabinets and closets.
Backing Sheet (BKL)
Backing materials are essential in the fabrication of decorative laminate clad surfaces to prevent warping and to protect against dimensional instability of both laminate and core in conditions of changing temperature and humidity. Backing sheets are non-decorative, and both economical and effective in the creation of a successful application. Produced
without a decorative face and available as standard (slightly thinner than decorative) or regrind (reclaimed decorative laminate with decorative sheet sanded off).
Flame Retardant (HGF)
Some of these laminates are capable of providing flame retardant characteristics as determined by test methods required by the authority having jurisdiction. HGF is the most common type used.
Through Color Decorative Laminates
The interest in specifying solid color decorative laminates and the resurgence of interest in very pale pastels and neutral shades have caused increasing concern with the brown line visible at glued decorative laminate edges.
Color through decorative laminates were formulated specifically to provide light colors without this brown line.
Color through decorative laminate may be applied to cores in three basic ways:
As sheets, to form a decorative face with a true monolithic look
As edge trims, to match a face of conventional decorative laminate or to accent a natural material such as wood or leather
As decorative inlays
Color through decorative laminate is produced with multiple layers of decorative papers, rather than the decorative plus kraft composition of conventional laminate. As a result, this material is slightly stiffer and slightly more brittle when flexed.
Selection of adhesive should take into consideration that a visible glue line may detract. Adhesive should not be tinted.
Solid Phenolic Laminates (SP)
High pressure decorative laminates are produced by several manufacturers in thicknesses adequate to preclude the use of a core minimum 1/8” (3.2 mm). Unlike conventional sheets, they may be drilled and tapped, and offer significant screw holding capacity. Depending on thickness, these laminates may be used for many flat applications, such as toilet and dressing room partitions, workbenches, shelving, and table tops. Panels are heavy for their size—an asset in sturdiness of the end application, but a factor which must be considered when planning for time and cost of labor and transportation as well as for support structures.
Static-Dissipative Laminates
High pressure decorative laminate is a good electrical insulator—in fact, it was for the specific purpose of electrical insulation that the product was originally developed. HPDL does not store static electricity, and it is therefore a suitable material for use in hospital areas, i.e.: operating rooms, X-ray rooms, and computer room controlled environments where the accumulation and retention of static electricity must be avoided. However, the growing need for work surfaces in areas such as electronic clean rooms, where electrostatic charges must be actively, continuously channeled away, has triggered the development of specifically conductive (static-dissipative) laminates such as: Anti-Static, Static Dissipative and Conductive. These HPDL sheets have a conductive layer enclosed in, or backing, the sheet. Connected to suitable grounding, they create a decorative, sturdy, practical work surface. Applications include electronic workbench tops and work areas around instrument monitoring devices, in lab testing environments, around photo equipment and on computer desktops. Antistatic laminates are produced in a number of compositions, thicknesses, colors and patterns. Consult manufacturers’ literature for details.
Chemical-Resistant Decorative Laminates
Chemical resistant HPDL offers the familiar advantages of HPDL: resistance to wear, conductive and radiant heat, and impact; as well as ease in cleaning, color fastness, and relatively light weight. Although this product may resist some chemicals, depending on the testing methods of the individual manufacture’s, it is the design professional’s responsibility to select the appropriate material for the chemical resistance required. These laminates may be applied on vertical as well as horizontal surfaces, to extend protection to cabinet doors and sides. And they may be post-formed for seamless edges. Adhesives should be specified carefully. Edges which may be exposed to chemical attack should be glued with chemical-resistant adhesives. Formulation of chemical-resistant decorative laminate differs from producer to producer. Consult product literature to make sure the material you specify meets the needs of your projects. They are available in varying thicknesses and a number of color and patterns depending on manufacturer.
Metal Faced Laminates
High pressure decorative laminates are produced with metal veneers and a backer of kraft paper and phenolic resin. The material used for much of the metal laminates is interior-type anodized aluminum. Other materials, including copper and nickel alloys may be specified in various formats; however, some metals, such as stainless steel or plated metal, are not conducive to machining with woodworking equipment.
Natural Wood Laminate
An excellent example of the ongoing evolution of the high pressure decorative laminate process. Presently, natural wood laminates may be specified in two formats; both feature thin veneers of woods bonded under high pressure and heat to a core of kraft papers and phenolic resins. One process leaves the face of the wood untreated, and ready to finish. The other adds a protective face of melamine resin. Performance characteristics vary with the presence or absence of the melamine resin. In both cases, the ease of cutting and bonding, as well as the wear resistance, improve in comparison to raw wood veneer. With the melamine face, the natural wood assumes much of the easy care and long wear properties of conventional high pressure decorative laminate. Sequence matching of natural wood laminate panels is extremely limited; consult the laminate manufacturer.
Flame Spread Rating of Decorative Laminates
Safer materials for interiors are a primary concern for commercial and institutional design professionals across North America. The threat of fire and its concomitant hazard of smoke has created a critical need for interior materials that address this concern without aesthetic sacrifice. Manufacturers of decorative laminate materials offer fire and smoke retardant grades for interior application. The addition of fire retardant does not affect the performance characteristics of decorative laminate; wear and stain resistance, ease of maintenance, and color stability remain very strong. Rated high pressure decorative laminates are evaluated and certified according to ASTM-E-84 test procedures (cataloged as ASTM-E-84 Tunnel Test; and as Test No. 723 by Underwriters Laboratories, Inc. With appropriate choices of core and adhesive, panels clad with fire-rated decorative laminate may be produced to comply with Class 1, I, or A, fire codes. Finished panels, already certified, may also be specified from some decorative laminate manufacturers. Major applications of rated decorative laminate include door, wall, and wainscot cladding in corridors, stairwells, entries, and elevators; as well as surfacing on fixtures and casework. These materials are supplied in both horizontal and vertical types, in a wide range of colors and patterns. They may not be post-formed; the special formulation that produces fire retardant is not compatible with heat forming. Adhesive choice for fire-rated decorative laminate is important. As with many types of fire retardant particleboard, some PVA adhesives are incompatible with the fire-retardant chemical composition of the decorative laminate material. Resorcinol adhesives are best for both chemical compatibility and flame spread rating of the end product. Contact adhesives do surprisingly well in some cases. Verify test ratings with your decorative laminate manufacturer.
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