The Paint Manual - Hempel

26
Metal
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 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 for painting metal
It’s 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 isn’t intended
to be part of the coating system, and
ideally should be removed before starting
the coating.
Before working on metal, it must be
free of corrosion. Remove salt and
contamination by high pressure
(min 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
paper to bright metal.
Prime bare metal with Light Primer,
thinned 20%, straight 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 can vary
greatly from the ambient temperature.