Marine Paints, Marine parts and House paints at trade prices direct to public – Servicing the marine industry since 1914

Metal

Steel and aluminium are widely used as boat construction materials due to their strength, ease of fabrication and water tightness. In the marine environment these materials will require painting for both resistance to corrosion and cosmetic appearance.

Steel surfaces
Steel is an excellent, easily worked, boat building material, suffering the defect of being chemically unstable in the presence of air and water. Corrosion of steel can however be simply and effectively overcome by careful surface preparation and the application of a paint system.

This provides a physical barrier to moisture and oxygen, isolating the steel surface from corrosive agents.

Aluminium and Galvanised surfaces
Aluminium and galvanised (zinc) surfaces are normally coated by an oxide layer which inhibits the adhesion of paint systems. In the case of aluminium, the oxide layer, whilst only being a few microns thick, is very tough and hard to remove. The white oxide deposits present on weathered zinc surfaces can build up and must be removed before painting. If a galvanised surface is to be immersed in marine conditions it is recommended that it is coated before weathering of the surface has occurred to any great extent.

With the correct selection of surface preparation and paint system, corrosion can be largely overcome enabling steel and aluminium hulls to offer long periods of service with minimal maintenance.

It is essential that any paint system chosen to protect a metal boat completely isolates the metal surface from air and water.

Prior to painting the surface must be free from corrosion. Inadequate preparation is the major cause for paint system failures.

Painting Metal

Steel and aluminium are widely used in boat construction due to their strength, ease of fabrication and water tightness. In the marine environment they will need painting to ensure resistance to corrosion and for a cosmetic finish. With the correct surface preparation and paint system, steel and aluminium hulls will give long periods of service with minimal maintenance.

Particular Tips when painting metal

  • It is essential that the paint system completely isolates the metal surface from air and water.
  • Metal plates are often pre-primed with a protective shop primer, this is not intended to be part of the coating system and ideally should be removed before starting the coating system.
  • Before doing any work on a metal surface it must be free from corrosion, and it is essential to remove salt and contamination by high pressure (minimum 2500 psi) freshwater washing.
  • Grit blast Steel to Sa2.5 (Swedish Visual Standard, ie near white metal) or abrade.
  • Grit blast Aluminium with non metal abrasives, or abrade with 60-120 grade abrasive paper to bright metal.
  • Bare metal must be primed with Light Primer thinned 25%, immediately after surface preparation to avoid contamination and surface deterioration before coating, and to obtain maximum adhesion to the surface.
  • Check surface temperature before coating as metal surfaces are prone to varying greatly from the ambient temperature.

For advice on repainting metal see the section on Repainting.

Steel – single pack/conventional

Product no of coats recoating interval @ 10oC recoating interval @ 20oC coverage m2/lt thickness per coat wft tickness per coat dft thinner
ABOVE THE WATERLINE
Primer Undercoat 3-4 8h-6d 4h-3d 12 100 40 823
Brilliant Enamel onto Primer Undercoat 8h-6d 4h-3d
Brilliant Enamel 2 16h-6d 8h-3d 13 75 40 823
BELOW THE WATERLINE
Underwater Primer 3-4 6h-indefinite 3h-indefinite 10 100 40 823
Hempel Antifouling onto Underwater Primer 2-3 9h-indefinite 5h-indefinite 13 75 40 808

Steel – two pack/high performance

Product no of coats recoating interval @ 10oC recoating interval @ 20oC coverage m2/lt thickness per coat wft tickness per coat dft thinner
ABOVE THE WATERLINE
Light Primerthinned 20% with 845 1 8h-60d 4h-30d 12 80 35 845
Light Primerthinned 5% 2-4 8h-60d 4h-30d 8 120 60 845
Poly Bestonto Light Primer 8h-6d 4h-3d
Poly Best 2 36h-10d 16h-5d 15 75 35 851 spray
871 brush
BELOW THE WATERLINE
Light Primerthinned 20% with 845 1 8h-60d 4h-30d 12 80 35 845
Light Primerthinned 5% 5 8h-60d 4h-30d 8 120 60 845
tie coat – Underwater Primer onto Light Primer 1 2h-4d 1h-2d 10 100 40 823
Hempel Antifouling onto Underwater Primer 2-3 9h-indefinite 5h-indefinite 13 75 40 808

Aluminium – two pack/high performance

Product no of coats recoating interval @ 10oC recoating interval @ 20oC coverage m2/lt thickness per coat wft tickness per coat dft thinner
ABOVE THE WATERLINE
Light Primerthinned 20% with 845 1 8h-60d 4h-30d 12 80 35 845
Light Primerthinned 5% 2-4 8h-60d 4h-30d 8 120 60 845
Poly Bestonto Light Primer 8h-6d 4h-3d
Poly Best 2 36h-10d 16h-5d 15 75 35 851 spray
871 brush
BELOW THE WATERLINE
Light Primerthinned 20% with 845 1 8h-60d 4h-30d 12 80 35 845
Light Primerthinned 5% 5 8h-60d 4h-30d 8 120 60* 845
tie coat – Underwater Primer onto Light Primer 1 2h-4d 1h-2d 10 100 40 823
Mille Antifouling onto Underwater Primer 2-3 9h-indefinite 5h-indefinite 13 75 40 808

* total 300 required