Osmosis. Hempel Paints

“Tendency of solvent to diffuse through porous partition into more concentrated solution” – that is how the Concise Oxford Dictionary describes “OSMOSIS”, which is a Greek word and means “pressure”. In the U.S.A., Osmosis is better defined as “BOATPOX”.

It is a regrettable fact that all glass-fiber boats absorb water. This results in a considerable increase in weight and an impediment to speed.

However, apart from this, the absorption of water is also the main reason for blistering in the gel coat.

Specialists who have studied Osmosis agree to the fact that epoxy is the best barrier against water. We are of the same opinion, and on the basis of many years of practical experience we recommend HEMPEL’S LIGHT PRIMER 4555 for protection of glass-fiber against Osmosis.

Osmosis is characterised by the appearance of blisters affecting the underwater areas of yachts and containing a pungent, acidic liquid.

In brief, Osmosis occurs when the gel-coat lacks sufficient water resistance. This weakness enables the water molecules to move freely in and out of the gel-coat, a process which is further accelerated when sailing in fresh waters. Blistering begins as moisture collects in pockets in the glass mat.