Marine plywood is a particular variety of plywood that’s been treated to withstand moisture. As the name implies, it’s often used on boats and other items that are in frequent contact with water. Whether it’s for marine use or exterior use, marine plywood still needs to be painted in order to be fully durable, and painting it properly can require some know-how.
Before applying any kind of paint, you need to sand marine plywood as you would any other type. Do this to remove imperfections in the wood and to help the primer adhere more easily to the surface. Make sure you wipe off all the sawdust after you’ve finished. A damp cloth is good for this (allow the wood to dry in this case before you proceed) or you can use a tack cloth for the job.
If you’re using marine plywood where it’s likely to come in contact with water, such as on the exterior of a house, you should use latex-based paints. Unlike oil-based paints, they’re very durable and will expand and contract with the wood so they won’t crack.
You need to apply a thin coat of latex-based primer to the wood first. Give it plenty of time to dry and then sand it down lightly. You should only sand just enough to roughen the surface a little. Doing this will let the paint make a good strong bond with the primer. Remove all the dust with a tack cloth again before you go ahead and begin to paint.
Choose Your Paint Carefully
What type of finish paint you use on the marine plywood is up to you, and how you’ll be using the wood. The gloss gives the hardest finish of all types, but the problem is that it also shows imperfections easily. The most utilitarian choice is semi-gloss. The hardness of the finish is virtually as good as gloss and it will cover any remaining imperfections in the wood. Just be sure to use latex-based paint over the latex primer.
Use the Right Technique
Start by putting on a thin coat of paint. There’s no need to sand between coats. Just allow it to dry, which should only take between two hours and three hours, and then apply another thin coat. In most cases, two coats of paint should be adequate, but you can add an extra coat for greater protection if you desire.
You can spray the paint on, but you’ll achieve a better thin coverage if you use either a brush or a roller to apply it. Start at the top, working from one side to the other. This will allow you to work in any drips as you move down the sheet of plywood. Don’t put too much paint on your brush before you begin painting; that’s just an invitation for excessive dripping.
Renew as Needed
The paint should be good for a few years, although this depends on which use the wood is put to. The greater its exposure to abuse and the elements, the more regularly it will need to be renewed. You should inspect the marine plywood regularly for wear.