Thanks to everyone who participates in this forum - I have learned so much from you all!
I am using some marine plywood to clad a planter box made out of H4 pine sleepers and will paint it with the aim of getting the smoothest possible finish. Ideally once painted, I would like it to not be immediately evident the planter is made of timber. I would appreciate some advice on the best primer to use for plywood to achieve the smoothest finish and the process to follow so that the grain of the plywood will not show through the paint (which will be Dulux Weathershield in Monument).
Welcome to the Bunnings Workshop community @Susan16DIY. It's wonderful to have you join us, and many thanks for your question about coating plywood.
Marine-grade plywood is typically also of a premium quality and comes with a smooth finish. With an undercoat and then two layers of topcoat, there shouldn't be any noticeable timber grain left. Another option would be to use cement sheeting for cladding your sleepers. It would be more resistant to moisture and have no grain to cover. My preference would be for you to use the cement sheeting as marine plywood will still decay if exposed to moisture for prolonged periods.
Please let me know if you have any questions.
Thanks so much Mitchell for your assistance. It is a great idea to use cement sheeting instead of marine plywood. I haven't worked with cement sheeting before. Can I please check if all cement sheeting is suitable to use outside and would I be able to cut a 9mm sheet with a scoring knife?
Any of the 9mm sheets are typically for exterior use and can be cut with a score and snap knife. They can also be drilled and screwed through, as with timber.
Thanks so much Mitchell, I really appreciate your assistance.