Metallic Paint Spray Application Guide for Polyurethane

Rigid polyurethane decorative profiles are manufactured with a closed-cell structural composition targeting a nominal density of ~150-220 kg/m³ (production target ~160 kg/m³) within a standard range of 150-220 kg/m³ (production target ~160 kg/m³). This high-density formulation limits water absorption to under 1% and offers operational thermal resistance between -100 °C / +80 °C. While products are supplied with a factory primer, secondary surface priming remains an optional step to enhance topcoat adhesion depending on site conditions. Decorative columns fabricated from this material are purely aesthetic and are non-load-bearing elements. For exterior installations, applying a UV-resistant topcoat is mandatory to protect against solar degradation.

Applying solvent-based gold, silver, or nacreous metallic paint requires a top-gravity feed spray gun equipped with a maximum nozzle orifice of 1.3mm. Fluid nozzles exceeding 1.3mm allow excessive paint volume, leading to metallic flake clumping, uneven orientation, and runs on vertical polyurethane surfaces. The gravity-feed container ensures a steady supply of dense metallic mixtures directly into the fluid needle chamber under controlled atomization air pressure.

Solvent-based metallic paints contain dense metallic particles that rapidly settle to the bottom of the spray cup during application. To maintain consistent color saturation and reflective alignment, the paint mixture must undergo thorough initial agitation followed by periodic mechanical re-mixing throughout the spraying process. Unstirred metallic paints result in noticeable shade variations and mottled mottling across interconnected polyurethane mouldings.

Achieving a streak-free metallic finish depends on maintaining a low fluid output combined with high atomization airflow. High air pressure breaks down the solvent carrier into a fine mist, allowing suspended metallic flakes to lay flat upon impact. Setting the spray gun fluid needle to restrict volume output prevents excessive wet-film thickness, which would otherwise allow heavy pigments to float, sag, or sink unequally into the coating film.

Before applying metallic coatings, polyurethane components must be correctly installed onto clean, dry surfaces. Profiles are cut at precise 45-degree miter angles and joined using dedicated polyurethane assembly adhesive; silicone sealants must never be used. Mechanical fastening using screws is mandatory to anchor the elements securely. Joint lines and mechanical fastener recesses are filled with putty, sanded smooth using 180-220 grit sandpaper, and sealed with primer prior to metallic application.

Metallic coatings must be built up using multiple thin, swift passes rather than a single heavy coat. After building uniform opacity with thin coats, a final misting (or dusting) coat is applied by increasing the gun distance slightly and maintaining high air pressure. This misting pass deposits lightly atomized particles evenly over the surface, correcting directional lap lines and unifying overall metallic sheen.