Water resistant finishes for planters
randomwoodguy
| Posted in General Discussion on
Hello all ,
Im going to be making a garden planter from timber just wondering what the advantages are of using just a water repellent or resistant finish over the usual exterior varnish are ? Or is the best finish just a clear coat varnish as id like to keep the natural look of the wood . Thanks for any feedback
Replies
Any varnish will take a beating outdoors. Doubly so on a planter. As much as I like the look, for outdoor projects I'll only use paint.
Thank you for your reply John
Tung oil is water resistant. It does darken the wood, however.
Choose the timber wisely, something that will hold up on its own outdoors. Ipe, black locust, cypress, or cedar would be good choices.
Don't use a film finish unless you like sanding and recoating. Go with a penetrating stain like those sold for decks, renewing the finish is as simple as hosing it down and recoating.
Any of the species above will last a longass time with no finish at all and just fade to a nice silver gray. I built my deck of ipe and it won't see a finish until it's time to sell the house. The ipe replaced a red cedar surface that lasted 25 years unfinished.
Its the UV that does the damage, as much or more than water. Oil finishes deteriorate from UV too. Finishes like Cabot Australian Timber Oil or Penefin products for outdoors, seem to last longer, but not long. I don't think they are truly oil but a blend of varnish.
Planter boxes for what? Flowers and such or food? While uv light will be tough on the exterior eventually what will happen is they will rot out from the inside. You will want a planting mix that retains water. Damp earth and wood are not compatable. With that said if you use a wood that has rot resistant properties they'll last a few years.. Sealing the inside gets sketchy particularly if you are growing vegetables. I have planters boxes made of redwood mostly, a couple of ipe, and some that are stone ,stone is best. I have a pretty large vegetable garden and had raised beds that lasted a few years but they eventually rotted out so I took them out and had been just growing in the ground. Last year was a banner year for gophers so I'm back to raised beds. Some of my beds are copperlined but that changes the economics,some are not. The beds destruct from the inside I've found so I don't find it necessary to treat the outside. I do however keep a finish on my redwood sided house,my decks , sheds and hundreds of feet of fencing.. The two best exterior oil finishes that I have found are penefin and TWP . The more pigment in the finish the more uv resistant it will be ,though both brands offer a clear version. Penefin uses as a base rosewood oil. TWP has the distinction of being the only EPA approved exterior finish. You can use it on your boat dock and not end up in handcuffs. Avoid any exterior oil that uses linseed oil as they tend to go black from the sun. I tried preservawood once and it went jet black on me and I had to practically drain a reservoir pressure washing it off! With an exterior oil finish refinishing is easy,just clean and reapply. Whatever brand you use they only last a couple of years if they are close to the ground and or in bright sunlight.
I recently installed 3 smaller raised planters to house both roses and tomatoes along with some random annuals. The material is actually shipping cases with corner hardware that were originally use to ship metal products. To protect both the wood and the vegetables I placed 6-mil plastic sheet around the interior (but not the bottom which is on grade). For the outside I applied Tung oil and will add more after the first growing season.
Thanks for all your replies everyone !
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