Marine ply12mm

[antifoul2020]

What is the best way to treat this plywood as it will be used externally
As boat seating any specific undercoat first
Many thanks

 

[Bingy man]

My choice would be a good quality yatcht varnish - sand your ply with 240 /329 grit sandpaper then apply at least 3 coats with 320 grit rub down between coats .

 

[Jameshow]

I'd thin the first coat too so it soaks in further.

 

[Seascaper]

What is the best way to treat this plywood as it will be used externally
As boat seating any specific undercoat first
Many thanks

Hello,
International produce two suitable products, Danboline and Metallic Pink Primer. Both provide a good base for undercoat and topcoats. They both provide wood preservative.
Regards

 

[sawtooth-9]

Depends on whether you want to paint or varnish.
If varnish, use an epoxy sealer - it's very thin, penetrates well, but not UV resistant - then follow with several coats of a good marine varnish.
If a painted finish is the aim, you can again seal with an epoxy, followed with a pink or grey primer and then apply top coats.

 

[Blister]

https://www.westsystem.com/projects/