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Lighting Equipment

Consistent appearance with outdoor weathering protection

Lighting equipment includes street-light poles, landscape-light columns, garden-light housings and other outdoor lighting facilities. Long-term exposure to sunlight, rain, ultraviolet radiation and pollutants places high demands on weatherability and colour stability.

Veri Coating offers high-durable polyester-HAA smooth powder and standard- or high-durable polyester-TGIC textured and smooth powders. These products are verified by xenon-arc and salt-spray testing, with weathering durability customisable from 3 to 10 years. TGIC grades provide a significant cost advantage over HAA grades.

Application notes: Aluminium should be chromated and steel phosphated, with the pretreatment film kept intact; hanging points, temperature and a film thickness of 60-120 um should be controlled.

Typical Powder Coating Challenges for Lighting Equipment

Inadequate Adhesion to Heat-Dissipating Metal SubstratesHeat-sink fin edges are prone to exposure and peeling, requiring stronger pretreatment and edge coverage.

Inadequate Adhesion to Heat-Dissipating Metal Substrates

Die-cast aluminium lamp housings and heat sinks often retain release agents, cutting fluids and oxide films and may have sharp cooling fins. Inadequate pretreatment, low edge film build or substrate contamination can expose fin edges, cause coating delamination and reduce adhesion after damp-heat exposure.

Formulation Design

  1. Select a polyester system with good wetting and adhesion on aluminium, and optimise its edge-coverage capability.
  2. For outdoor luminaires, use a standard-durable polyester system suited to the weathering requirement; for highly corrosive service, evaluate an epoxy powder primer with a polyester topcoat.

Process Control

  1. Thoroughly remove release agents and machining oils, then use a validated chromate, zirconium or silane pretreatment.
  2. Deburr sharp heat-sink fins and coat grooves and inter-fin spaces before the outer surfaces.
  3. Confirm cure using actual part temperature to prevent local undercure caused by temperature differences between thick and thin sections.
Validation Focus
  • Cross-hatch adhesion
  • Film thickness at fin edges
  • Adhesion after damp heat
  • Edge delamination after salt spray
Blistering on Coated Die CastingsResidual gas escapes as the substrate heats; preheating and a controlled cure profile are required.

Blistering on Coated Die Castings

Porosity in die-cast aluminium lamp housings can trap air, moisture or residual release agent. During cure, escaping gas can produce pinholes, blisters and craters, especially on thick-walled or recycled-aluminium castings.

Formulation Design

  1. Use a polyester powder with an extended flow window or an outgassing-tolerant design so gas can escape before the molten film closes.
  2. Optimise the degassing additive and melt viscosity without materially impairing flow or weathering resistance.

Process Control

  1. Preheat parts for outgassing before coating, with temperature and time established by testing.
  2. Control post-pretreatment drying to prevent moisture reabsorption; for thick-walled parts, extend the heat-up stage rather than only the high-temperature dwell.
  3. Avoid excessive film build; where necessary, apply multiple thin coats and verify intercoat adhesion.
Validation Focus
  • Pinholes/blister count
  • Defects before and after preheating
  • Film-thickness sensitivity
  • Retention of adhesion and weatherability