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Best weather proofing finish for an outdoor table.

7K views 4 replies 5 participants last post by  wapakfred 
#1 · (Edited by Moderator)
First time post here.

I was interested in getting your opinions on the best finish for an outdoor table I plan on building this weekend. It is going to be made from your standard pressure treated weather shield lumber that one can get at home depot. I'd like to stain it to a dark walnut color and then hit it with some sort of clear protectant. Also, at what grit sandpaper should i stop sanding? i understand that if i go to high in grits it can inhibit stain from taking….

Thank you for your feedback,

Jeremy
 
#2 ·
To start with, pressure treated lumber is not suitable for anything you are going to eat off of. Crap is toxic.

Secondly, it's pumped full of liquid chemicals so it is very wet and I doubt you could get any stain or finish to stick to it; long term.

Why not use some naturally weather resistant wood like Cypress or Cedar or even White Oak.

Most stained finishes don't like to be sanded above 220 grit. 180 is usually high enough.
 
#3 · (Edited by Moderator)
If you're going to be using pressure treated lumber, make sure you're using an endgrain sealer. Aside from that you dont really need finish to protect the wood. My deck has pressure treated beams that are decades old and they still have great color.

For external finishes on untreated wood my favorite is Epifanes clear marine varnish. You can usually find this at Marine supply stores and it's a well proven product. I really like it because it produces a great finish, provides U.V. protection and yearly maintenance is a snap (light sand and slop on a couple more coats). I put this on my french doors on the south side of my home which get wrecked every year. It does however take at least 7 coats withs long dry times:
https://epifanes.com/na/store/varnishes-and-clear-finishes/
I generally apply it with a brush, which requires some thinning (Epifanes sells a brushing thinner which is just NAptha IIRC).

A linseed oil would probably work, but wouldnt' have any U.V. protection. A polyurethane finish would probably degrade after a year and require some heavy stripping + sanding to prep for re-coating. I've tried a couple box store Spar varnish which horrible success.

Like crank said, pressure treated lumber would be nasty stuff for the top of a table. You see a lot of outdoor furniture made of cedar because it is really rot resistant and can be coated with a light oil for easy annual maintenance. I would probably use a Cedar, Fir or CVG top because we have plenty of that in this area. You could even use something like IPE decking which is readily available (just make sure you apply a hard finish to make it safe to eat off of).

The more staining i do, the less i like it. Whatever wood you decide upon, you'll probably need to pre-treat it with something like Bulleyes Sanding Sealer to prevent streaking. This will change the color slightly, bring treated samples to the store to make the color you want. In seattle there is a store called Dalys which specializes in color matching stains, there is probably something similar in your location. If you're using a stain, you'll likely be stripping and sanding each year.

For a finish with Epifanes, i think they recommend stopping at 220 grit. Unless you're doing something like a poly/oil blend or straight oil going above 320 grit is a waste and typically not recommended for most products.

Keep in mind that your finish will last 2 years max. In the Northwest, more like 6-10 months.
 
#4 ·
Welcome to Lumberjocks

lots of different opinions on this. The problem with stains and finish outside is simply redoing them on a regular basis. Is there harsh chemicals in the wood? Yes. The same with the finishing products that most of us use. Treated lumber comes out very wet, but dries and takes stain and finish fine (I build a lot of outdoor furniture). I like using Cabot Australian Timber Oil. I like the way it goes on and seems to hold up well for me. As far as if it is safe to use for a table top, you can find plenty of info on the Web to support both sides of the argument. It's simply your decision. I would not have a problem with it.
 
#5 ·
If you stick with your plan (stain and clear coat) I think I would use unitinted oil based paint. The base used for mixing darker colors (usually #4, maybe #5) looks very much like varnish once dried (most brands) and has UV inhibitors. It's also quite a bit cheaper than a true marine spar varnish, which would be the first choice (not box store spar varnishes). To see if the paint base will dry clear, stick a paint paddle in it and let it dry…some brands can be cloudy. I used to use Olympic (Lowes) but they've stopped carrying any oil based paints; that's a key point: get the oil base.
 
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