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Diagnosing Osmosis

Planning the  Work


Inspecting & Drying

Materials Required

Epoxy Application

We recommend Advanced Osmosis Technologies to provide you with an expert osmosis diagnosis and repair service

Inspecting and Drying

Peeled GRP laminate that is in good condition has a solid, resin rich appearance

INSPECTING FIBREGLASS LAMINATE FOR OSMOSIS DAMAGE Inspect the laminate at this stage to ensure that all damaged laminate has been removed. A healthy laminate is a uniform, translucent colour and the reinforcing glass strands are faintly visible. Areas that appear snowy white or in which the reinforcing fibres show white, but are otherwise dry and firm to the touch, are termed “resin-starved” and indicate the fibres were not thoroughly saturated with resin during the lay-up. The fibres will have a tendency to absorb water. This condition is serious but shallow areas can be effectively treated after drying by saturating the area thoroughly with  SAFEGUARD LVP. This is a low viscosity epoxy material that will penetrate porous laminate displacing trapped air.

Extensive areas of deep resin-starved lay-up,Osmosis damaged GRP laminate should be saturated with Safeguard LVP to consolidate and strengthen it. deep pitting, soft laminate, apparent de lamination of the underlying layers of reinforcement, or the presence of any fluid seepage indicate significant damage to the hull structure. If any of these conditions are found, consult a professional surveyor experienced with GRP construction for advice. These areas will have to be removed with a gel planer or by grinding and replaced with new epoxy laminate before application of Safeguard.

RINSING AND DRYING THE LAMINATE  After removing the gel-coat and any damaged laminate it is essential to thoroughly wash the hull several times with fresh water to remove any salts formed by the osmosis.  

This is best done with a high-pressure hot water washer. IfHoles in GRP laminate should be primed with Safeguard LVP and filled with Easy Fair epoxy filler any salts remain in or on the laminate, they will continue to attract moisture from the atmosphere and the hull will never dry properly. The washing process should be carried out several times during the first week after removal of the gel-coat. After washing, the hull must be left to dry. This can be done in the open and may take several weeks to several months.

The drying process can be hastened by using steam to clean the laminate or by using Hotvac equipment.

The moisture level should be monitored each week. A moisture reading of under 5% is desirable. If the hull gives readings in excess of this amount, it generally indicates that salts are still present and further rinsing is required. Check too, that the inside of the hull is thoroughly clean, dry and salt-free if high moisture readings persist. The use of heat may be required to achieve low moisture readings. However, having  the hull under cover may speed up the drying process and make the following steps less dependent on the weather.

This picture shows the result of severe osmosis damage to a fibreglass hull