sealing plywood

[Jim Colombo]

What is the best sealer for plywood that will be used outdoors?

Thanks,
Jim

[Jamie Buxton]

Paint. It is better than varnish because the pigments in the paint help protect the paint and the wood from sunlight.

Use plywood intended for outside exposure -- exterior glue.

Be very careful to paint the edges thoroughly. Work the paint into any cracks or voids, and into the end grains. Edges are where outside plywood first fails.

[Doug Garson]

It may depend on the intended end use. For example, I don't think paint would work for plywood that will be submerged. Stitch and glue boat construction like kayaks, canoes and sailboats use marine grade plywood sealed in epoxy and then coated with spar varnish or paint for UV protection.

[Jim Colombo]

This will not be submerged. I found some 1/2" birch plywood that is rated for outdoor use. The process I was thinking of would be to sand, seal, paint on the artwork and seal. What do you think?

Jim

[Mel Fulks]

Jim, I don't know . I've not seen or used any birch plywood outdoors. I do think there is a difference in out door under cover and outdoor in the rain. Years ago I thought good paint would protect almost anything outside. I'm no scientist but I've pretty much proved that good paint does not protect an inferior material for long.

[Stew Hagerty]

First, use "treated" exterior grade plywood. Then paint all surfaces. If there are areas that you cannot paint for some reason then apply an exterior clear finish. if you need to use a water-based clearcoat, I would recommend General Finishes "Exterior 450".

[Dan Rude]

If you are doing Artwork use MDO. It paints very well and has a special smooth paper face. It is used for outdoor signs. Dan

[roger wiegand]

I've had little success with ordinary paint. For my recent project of replacing a trailer floor, after a lot of searching, ended up using a clear penetrating epoxy sealer with a topcoat of a pre-catalyzed urethane finish (a sherwin williams industrial coating product, about $200/gallon)-- basically treated it like a boat.

It's only been two years, but so far it still looks like new with no evidence of failure at the edges, so I'm optimistic. It's already much more successful than the prior paint.

[Sam Murdoch]

If you are doing Artwork use MDO. It paints very well and has a special smooth paper face. It is used for outdoor signs. Dan

This is what I would do and prime with an excellent exterior grade primer. For super duty protection glue solid wood strips around the perimeter using epoxy - OR - simply paint all the edges with thin epoxy - let dry - do again - then paint.