Anyone know why bottom paint that is ~ 2-3 inches just above the waterline would be flaking off? Note it is the second 'top' layer of bottom paint (black) that is flaking off of the bottom layer (blue) after a couple of months. The same type ablative paint was applied within a day, just different colors. Below the water line , the black coat is fine. Manufacture of 'Blue Water' didn't know why this would occur. thx
Bottom paint above the water line
- Thread starter windsmaker
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The problem with bottom paint above the waterline is that its subject to constant 'dipping' of the hull (even at a slip or mooring) by wave action which causes constant 'drying then wetting' etc. of the paint. This dipping action plus the waves that constantly 'travel along' the hull create a 'scouring action' that requires such paint to need superior 'adhesion' to the below layers, etc. .... and usually or can cause such paint, especially an ablative type paint, to have 'premature wear' and relatively short service live in comparison to 'underwater' paint. Such exposed paint HAS to be applied over preexisting bottom paint with lots of 'tooth' (course sanding of the underlying paint) to promote resistance to flaking and wear yet shouldnt be too thick (which also promotes 'flaking').
What do the instructions call for on overcoating as Micron extra (for example) is 16 hours minimum between coats which does not allow more than one coat per day
The same type ablative paint was applied within a day
Blue water instructions
Estimated Dry Times: Bottom paints are designed for overcoating after an overnight dry. Prior to launching, allow a minimum dry of overnight. If drying conditions are poor, or if paint was applied too thickly, longer periods of drying will be required. Fresh coats of paint must be thoroughly dry before overcoating.
The same type ablative paint was applied within a day
Blue water instructions
Estimated Dry Times: Bottom paints are designed for overcoating after an overnight dry. Prior to launching, allow a minimum dry of overnight. If drying conditions are poor, or if paint was applied too thickly, longer periods of drying will be required. Fresh coats of paint must be thoroughly dry before overcoating.
I used Blue Water paint on my last bottom job. Went two years with a little very minor flaking/ peeling. I thought it performed well for the price. I had 1 cote applied with a roller. two cotes above the water line. Had Matt @ Fast Bottoms clean it every three months. When it was hauled, No barnacles.
Well, it was every two months, but who's counting?
Nor should there have been. Barnacles are not a particular problem in the Bay Area. Plus, with a relatively frequent service schedule (like the one you were on) and gentle cleanings, there should be no hard growth of any kind evident on paint in decent condition.
Thanks, for input,
I still can't explain why this top coat is flaking off above the waterline.
If the paint was not applied correctly ( drying time, or substrate) than why is the paint below the water line is not flaking off and doing ok. You don't apply paint above and below the waterline differently. There is something different about the exposure to air and water interface that appear to be causing flaking .
wave action (or constant wetting and drying) is a possibility but I would have expected this would be a common problem with ablatives ..... but it isn't.
Perhaps the top paint layer which is exposed directly to sun is resulting in a overheating of the top layer causing it the loose adhesion from the underlayer. Below the waterline the heat is dissipated and constant and paint adhesion is fine. This would indicate that differences in paint color may affect the adhesion properties above the water line. That is , the color black (a high heat absorber) should not be appied over blue layer and result in heat differential in the layers and flaking ..
ok , just a far out idea.
I still can't explain why this top coat is flaking off above the waterline.
If the paint was not applied correctly ( drying time, or substrate) than why is the paint below the water line is not flaking off and doing ok. You don't apply paint above and below the waterline differently. There is something different about the exposure to air and water interface that appear to be causing flaking .
wave action (or constant wetting and drying) is a possibility but I would have expected this would be a common problem with ablatives ..... but it isn't.
Perhaps the top paint layer which is exposed directly to sun is resulting in a overheating of the top layer causing it the loose adhesion from the underlayer. Below the waterline the heat is dissipated and constant and paint adhesion is fine. This would indicate that differences in paint color may affect the adhesion properties above the water line. That is , the color black (a high heat absorber) should not be appied over blue layer and result in heat differential in the layers and flaking ..
ok , just a far out idea.
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