Antifouling Paints
Copper, or cuprous oxide (a
copper compound), keeps marine flora and fauna from growing on the bottom
of your boat. Toxicants such as copper, are the key to the effectiveness
of these types of antifouling paints. Not all antifouling paints are the
same. They contain different amounts of copper, have different ways of
releasing the copper, and have different binders (the material which keeps
the copper in suspension.)
Amount of Copper
One difference in antifouling paints is the amount of copper the paint
contains. Don't be fooled - more isn't necessarily better. The secret
to copper's effectiveness is how fast it's released. The percentage
of copper a paint contains will give you an idea of how long the paint
will last, but remember that binder type, water conditions, boat speed,
frequency of boat use, etc. will also affect service life.
Conventional
Paint Copper Release
With conventional paints, copper is evenly spread throughout the hard
paint film. Once the boat is in the water, the particles closest to
the surface dissolve, but the paint itself does not. When the copper
dissolves, there is a hole which lets the water dissolve copper further
inside the paint. This happens repeatedly until all the copper is gone.
Soluble
and Ablative Paint Copper Release
Soluble and ablative paints work quite differently. With these paints,
the paint itself slowly wears away as the copper dissolves. This continually
exposes new copper. The rate of erosion is determined by a number of
factors including the chemical composition of the paint, boat speed,
and turbulence. Of course, the thickness of the paint layer determines
how long the paint itself will last.
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