The Paint Manual - Hempel

Osmosis treatment
When to use an osmosis treatment.
If the laminate and/or gelcoat is poor
and there are indications of osmosis, a
full Osmosis Treatment may be required.
Full treatment involves the removal of
the gelcoat which, under the correct
Preparation
The gelcoat will need completely removing
to allow the hull to dry out.
Hand Power Tools
Grinders provide an inexpensive means
of removing the gelcoat and preparing
the surface. The disadvantage is the time
to complete the task and the amount of
dust produced. Protective clothing must
be worn by the operator, especially dust
mask and eye protection
Slurry or Abrasive Blasting
Either of these methods successfully
remove the gelcoat and prepare the hull
for the application of Gel/High Protect.
Any hull defects will become apparent
during blasting, ie voids in the laminate.
A professional with the correct equipment
is needed to carry out either of these
methods.
conditions, will allow the hull to dry out to
the recommended levels, before coating
the bare laminate with Gel/High Protect,
replacing the gelcoat to give the hull a
moisture resistant coating.
Preparation and specification for osmosis treatment.
Gelcoat Peeling
A gelcoat peeler, planes away the gelcoat
at a preset depth resulting in an even and
smooth finish. This is generally accepted
as being the most effective method for
removing gelcoat. Once peeled, the
surface will require abrading with 40 grit
grinding disks, or light slurry blasting to
provide a key for the Gel/High Protect.
This method requires a professional
operator.
Once the gelcoat has been removed, the
hull should be steam cleaned,
or at least pressure washed to remove
salts and other contaminates which are
present in the laminate due to osmosis.
The salts and other contaminates will
continue to come to the surface so it is
necessary to repeatedly wash the hull,
once a day is recommended.
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Osmosis treatment