Liquid painting has been the workhorse of industrial finishing for over a century, and despite the rise of powder coating it remains the correct choice for a significant class of components — anywhere thin films, fine colour gradients, heat-sensitive substrates, or small-batch bespoke colours are required. At Autotek Steel Engineers, our conveyorized liquid paint line delivers consistent film build, exceptional colour accuracy and excellent bond strength across appearance-critical and functional sheet metal components.
What is liquid painting?
Liquid painting is the application of wet paint — a suspension of pigment, binder resin and carrier solvent or water — onto a prepared metal surface via spray, dip or flow-coat. After application, the paint dries either by solvent evaporation (lacquers, acrylics) or by chemical cross-linking (2K polyurethanes, epoxies). The result is a smooth, colour-accurate film typically 20-80 microns thick, with excellent appearance and tunable chemistry for specific performance requirements.
Liquid vs powder — when each wins
Choose liquid painting when:
- Part contains heat-sensitive components — plastic, rubber, electronics, pre-assembled units that cannot survive 180-200°C oven cure.
- Very thin film is required (<30 μm) for dimensional or aesthetic reasons.
- Fine colour gradients, metallic effects or pearlescent finishes are specified.
- Small-batch custom colours are routine — liquid paint mixing is faster and lower-minimum than powder reformulation.
- Touch-up and on-site application is part of the supply requirement.
Choose powder coating when:
- Thick, chip-resistant, durable films (60-300 μm) are specified.
- Volumes are high and colours are standard.
- Outdoor UV, corrosion and mechanical abrasion resistance matter more than colour matching.
Paint chemistries we run
- Acrylic polyurethane (2K PU) — the OEM standard for decorative sheet metal; excellent colour retention, gloss, chemical resistance.
- Alkyd enamel — cost-effective, durable single-pack finish for industrial equipment.
- Epoxy primer — exceptional adhesion and corrosion resistance; used as primer under topcoat.
- Water-based acrylic — low-VOC formulation for environmentally sensitive applications.
Our conveyorized liquid paint line
- Pre-treatment — degreasing, phosphating, rinse, dry-off bake (identical to our powder coating pre-treatment where specified).
- Primer application — epoxy or 2K PU primer at 20-30 μm if specified.
- Flash-off / primer cure.
- Topcoat application — spray gun in conveyorized booth, operator-controlled film build.
- Flash-off, then oven cure — typically 60-80°C for 20-40 minutes depending on chemistry.
- Inspection & batch documentation.
Typical liquid painting applications
- Appearance-critical sheet metal — commercial vehicle body panels, appliance exteriors, premium furniture.
- Pre-assembled units — finished subassemblies containing non-metallic components.
- Low-volume custom colour parts — branded equipment, specialty machinery.
- Heat-sensitive substrates — aluminium parts with inserts, bonded assemblies.
- Touch-up and field repair — matching factory finishes on-site.
Specs & quality control
- Film thickness: 20-80 microns dry, measured on every batch.
- Colour tolerance: Delta-E < 1.0 vs master standard (measured on colorimeter).
- Adhesion: pass ASTM D3359 cross-hatch test at 5B.
- Impact & hardness: standard tests per the quality testing guide.
- Colour matching: RAL, Pantone, custom master-chip matching available.