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alfaquad

Paint won't stick!!!

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Good afternoon,

I have a 1963 Penn Yan wooden lapstrake that had its bottom replaced about 15 years ago.  Paint adheres to all original strakes just fine.  For the last 15 years, the "new" strakes don't hold onto the paint anywhere as well as the original. The new strakes are of similar material (plywood).  I have tried belt sanding the new strakes to the bare wood and priming, then painting (white and copper bottom).  Looks great but by the end of the season (3 months) it is peeling.

I was going to try again with TotalBoat Primer and WetEdge. Sanding to bare wood first.

Couple questions... primer states not to use above 90% humidity and less than 20% surface moisture (of wood).. Humidity I understand (Massachusetts).  Surface moisture???  With one of those unreliable meters???   Should I doo something else to the bare wood before priming to assure adhesion???

Thanks

 

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I would try prime with Interlux Interprime first after sanding down to bare wood for the areas above the waterline.   Apply 2-3 coats. This will seal the wood and filler and then the paint or varnish of choice can be applied as directed. PLYWOOD: It is important to saturate the porous white summer grain of the wood until it takes on a glossy appearance. At least 2 coats will be required to reach this condition. Once gloss is obtained, the wood should be sanded with 120 grade (grit) paper before applying finish coats of paint or varnish.  

Below the waterline, sand down to bare wood, thin the bottom paint with 10% thinner, apply a coat.  When dry apply another coat of straight bottom paint.

 

 

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You certainly would't want to paint at 90% humidity and 20% surface moisture is a lot.  Green wood can approach 50% moisture content while kiln dried averages around 12% moisture.  Air dried green lumber will go down to 20 to 25% over time.  That is overall core dryness not surface moisture which would be much less.  So the bottom line is you need to surface moisture to be low and humidity when applying to be less than 90%.

 

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