The Technique of FURNITURE MAKING
Decorative plastic laminates
Familiarly known as Formica, Wilson Art, Consulweld, etc., these are composed of layers of kraft paper impregnated with phenolic resins, while the surface pattern, which can be purely decorative in an infinite range of designs or an exact simulation of real wood grains, is printed on a cover paper, and coated with a scratch-resistant surface of melamine resin. Figure 29:1 shows (A) the kraft papers, (B) the cover paper and (C) the melamine coating. Heat pressing of the assembled pack between stainless-steel platens polished to mirror finish induces a chemical change or polymerization, resulting in a homogeneous sheet possessing outstanding qualities of lightness, toughness, durability and resistance to heat, moisture, acids and alkalis, etc. Standard sheets with the pattern on one face only are usually 1/16 in (0.062 in or 1.58 mm), but a full range of thicknesses is also available, 0.032 in (0.81 mm) for vertical facings, wall claddings, etc., 0.040 in (1.01 mm) for light use in horizontal positions, 0.052 in (1.32 mm) for post forming (heat bending), and 0.10 in (2.54 mm) to 11/2 in (38 mm) built up of separate laminations or with a sandwich core of other materials (ply, etc.). Thicknesses of 1/8 in (3.17 mm) and over are self-supporting (29:2). A cheap-quality backing or balancing veneer composed of kraft papers only with no surface pattern is available for use on the undersides of core material to counteract the pull.
Cutting procedures
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Laminated plastic veneers can be cut with circular saws, using square tipped teeth without set, band-saws with hack-saw-shaped teeth, or fine-toothed backed tenon-saws, in all cases cutting with the face side up. For machine-saws in production-work tungsten-carbide teeth should be used, for the resin content is very hard on cutting edges; while if there is any tendency for the back to chip or 'tear out' with any type of saw the teeth should be resharpened, and the plastic sheet firmly supported with applied top pressure if possible. An alternative hand method which gives no tear is to score the face with a hardened steel scraper or cutting tool—a special blade is available for Stanley trimming - knives—and the sheet will then snap easily with a clean fracture, as in glass cutting. Narrow cross-cuts, corners, etc. can be cut with a finetoothed hack-saw, while for contour cutting portable electric sabre-saws or fret-saws with
29 Decorative plastic laminate details
metal-piercing blades can be used, but support must be adequate with strips of waste material, hardboard, etc. clamped to the face to prevent chipping on the upward stroke.
