The Paint Manual - Hempel

Osmosis protection
When to use an osmosis protection.
New boats
The best initial defence against osmosis is
the correct methods and materials used
during build. The higher the standard of
the GRP laminate at construction, the
greater the defence against osmosis. The
addition of Gel/High Protect will give the
ultimate protection to a new hull.
Preparation and specification for osmosis protection.
New boats
Used boats
New gelcoat should be cleaned thoroughly Remove all old paint or antifouling by
with Degreaser or Pre-Clean to remove manual dry scraping or having the hull
mould release agents used in the
grit or slurry blasted (this is a quick
construction of the hull. For more
and efficient way of removing the old
information refer to Surface preparation: paint layers and also provides a well
cleaning and degreasing, on page 11. keyed surface which will require little
After degreasing, the surface should
extra preparation). Whichever method is
be abraded with 60-100 grade abrasive
used the hull should have an even matt
paper, or lightly slurry blasted, and
finish with no trace of previous coatings.
washed off with fresh water. When dry the
Freshwater wash the hull and allow to dry.
hull should have an even matt finish.
Any minor cracks
and blemishes should be primed and filled
with Epoxy Filler.
Key advice:
Correct surface preparation is vital for a
long-lasting protective finish. Time spent
at this stage is well invested.
Used boats
Before applying a protective epoxy coating
to older boats the condition of both
the laminate and gelcoat need to be
assessed. If in doubt, seek professional
advice. If the hull condition is suitable,
Osmosis Protection can be carried out
using Gel/High Protect, if the condition
is not good enough Treatment is
recommended.
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Osmosis Protection