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I read a lot of Bob Flexner on the topic of finishing wood furniture. I don’t really enjoy finishing wood as much as Bob does, but maybe that’s why I have gotten so interested in learning more. What am I doing wrong that has made it less enjoyable for me in the past? How can I improve my understanding of the skills? One thing that Bob usually emphasizes in his articles on how to finish wood is that you should always try to “start with your finish,” which means test a few finishes for each project before you jump into the final piece.

Learning how to finish wood is a matter of experimentation.

Learning how to finish wood is a matter of experimentation.

Last night I went to a regional cedar sawmill and picked up a load of Northern White for my Adirondack chair project. Since I have about 6 months before I need to deliver the finished pieces to their recipients, I figure this is a perfect opportunity to test several finish options beforehand. I can even leave the test pieces outside in the elements and see how they fare.

Here are the wood finish options I’m considering:

1) Primer and paint. I don’t actually need to test this one, since I know how it will look and I know (from reading Bob) that it is a very effective outdoor finish.

2) No finish. This will be a very easy one to test. I’ll cut a sample piece and plane 4 sides to expose the unfinished surfaces. Cedar is supposed to be pretty good on its own. We’ll see how it goes!

3) Thompson water seal. A blog reader suggested this one. I know it is easy to find at the home center, so I figure I’ll give it a shot.

4) Natural oils from the woodworking specialty store. Again, this was a reader suggestion. It will be interesting to compare the specialty product to the home center product.

5) Polyurethane. I have used this in the past, so it will be easy to apply. What I don’t know is how it looks on cedar and how it will fare outside.

6) Wiping varnish, sometimes mislabeled as Tung oil. I know this works nicely on indoor projects. We’ll see how it compares to poly for the outdoors.

I will probably experiment with a stain or two in combination with some of the above finishes. Bob recommends using a “sealer coat” under your stain on soft woods like cedar. A sealer coat is simply a single coat of your chosen finish, applied to the bare wood. After applying the sealer coat and letting it dry, sand it smooth and apply the stain. Then proceed with your finish coats.

What have you learned from Bob Flexner about how to finish wood? Tell us in the comments. And if you don’t have a copy of Bob’s book or ebook, buy it today!

Dan Farnbach

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Showing 16 comments
  • jarvisbrowning

    I’ve used Olympic penetrating Oil Deck stain on White Oak After one year it seems to be holding up well on my Rocking Chairs one for me and the Mrs. I chose clear but the color is really honey.

  • swirt

    I highly recommend Cetol1 from Sikkens. It looks close to a furniture grade indoor finish but is breathable and is made to handle the rigors of outdoor life. Every few years you wipe down the piece with some steel wool to remove any debris that sticks to the surface of outdoor furniture and then apply another coat. This actually melts into the original finish and makes it look good as new.

  • Sawdust

    Dan, the first thing I would suggest is that you think about exactly what type of ongoing work you want to do to maintain your project in the years to come. Any outdoor project will require ongoing maintenance unless you want it to simply rot. Key issues are UV resistance and ease of application associated with the ongoing maintenance.

    Think about it. You’ll find the answer that most suits your style of work.

  • Clay Dowling

    From experience, polyurethanes without UV blockers will have a very short and unhappy life. It turns out that sunlight degrades urethanes very quickly. Over the space of a year, the finish will be completely gone from the wood.

  • seancphillips

    I can tell you I used Minwax Helmsman VOC Spar Varnish, cut about 25%, and applied several coats to a crappy little outdoor table I made last spring. It sits next to the pool for drinks, phones, and that. I just cheked it and already the finish has cracked and areas of wood exposed. So, I guess it’s either the cutting it, or not enough coats, but I’m not impressed with my results.

    And I’m in Dallas….known for its harsh winters.

  • Tom K

    I highly recommend a coat of Rot Doctor, a penetrating two-part epoxy sealer that essentially platicises the wood and keeps it from rotting. Better yet, coat all the pieces before assembly so that the joints, which are vulnerable to moisture retention, are protected.
    It’s not cheap, and you can only order it online, but a little goes a long way. Thompsons is good, but it has to be recoated every year, it wears off.

    This could be a final finish, or as a primer- undercoat for paint, varnish etc. I don’t build anything that goes outside anymore without a coat of this stuff

    Tom Kokontis & Company

  • phil1949

    Have a look at the test done by this chap.

  • drsmith

    Well, my experience with Thompson water seal is a bit different than one of the comments given above. I rented a house that had a giant window over the bathroom sink. There were no mirrors in this bathroom, so I decided to do something about the window situation that would both give me some privacy and a place to mount a mirror.

    I got some birch plywood from the home center and cut it to just fit in the opening provided by the window. I attached a couple of spring loaded curtain rods to the back side to hold it in place and put a proper mirror on the front side. Now think about this a moment. A bathroom, plywood, and a cold window on the back side – there should be condensation all over the place, right?

    I put two coats of Thompson water seal on the plywood before I assembled everything. In 10 years of living in that house, the plywood didn’t warp, bubble, or show even the slightest signs that moisture was a problem. I had figured that if I got two years out of it, I was doing pretty well – it was after all a quick solution to a problem that was bugging me and I could still use the window if needed. It actually worked much better than I had anticipated.

    I’m now building pine shelving for my basement workshop and, yes, I will be giving a coat or two of the same stuff.

  • MikeyD

    You need to go to your local boat shop. Marine finishes are great. Expensive, but worth it. I’ve used stuff from Sikkens with good results.

  • BobGroh

    Really enjoyed Keithm’s comments – a few chuckles mixed in with a lot of practical information. Another place you might go for advice is good ol’ Consumer Reports. They have done a number of tests over the years on stains and paints for decks, fences and houses – good tests with long term outdoor aging thrown into the mix. For decks, I believe their top recommendations were for semi-solid stains. We used a semi-solid stain (from Home Depot but I can’t think of the brand at this moment) for our deck a couple of years ago and it has done great – much better than anything else we tried for the 30 years we have lived here. By the way, skip the Thompson Water Seal – it just does not do the job well.

  • keithm

    Also, Bob Flexner is my hero. I’ve learned very much from finishing from him. Before “Understanding Wood FInishes,” I was the typical, hate to finish, found one that worked and used it for everything woodworker.

  • keithm

    There’s another option, untinted exterior paint. Included is a copied text that has been the source of this idea. Polyurethane (even the so-called “spar urethane”) is a terrible idea, as you will read. Last names redacted.

    In a recent post my friend, Steve, made reference to my tests of doggie sprinkling on exterior finishes. I figure after almost a year of testing it is time to post some interesting discoveries. As a preface, allow me to set the stage. Almost daily there is a posting about clear, exterior finishes for doors, chairs, signs and such. Responses run the gamut from diehard marine finishes to apply a coat of primer and then paint. Each of these has a bit of a problem. Marine finishes are not always the easiest to find, and it grieves me to think of a lovely oak, teak, mahogany, fir, redwood or similar nice wood door painted in mauve goop.

    Bob (from Florida) inspired me with his continuing and accurate statements about the failings of a clear coat and the advantages of a good quality exterior paint. I decided after lots of reflection that he really was right but there was always the picture of mauve in my mind. So, how could one take advantage of his advice and yet capitalize on the beauty of a nice wood? I began to reflect on the characteristics of paint. Now comes the boredom…

    There were several things I knew about paint:

    Exterior paints contain a mildewcide and a fungicide that a (marine) varnish does not.
    The best quality paints will contain a UV (inhibitor) and trans-oxide pigments in very high percentages.
    Almost all paint is custom mixed by the store. The retailer maintains a large supply of base products that are used to achieve the desired color.

    There are generally four base products and the specific one for your paint is determined by your color choice. These base products are either named or numbered. They are named pastel, deep, tint and neutral. If numbered it is cleverly 1, 2, 3 and 4 with the exception of Olympic who numbers 1, 2, 3 and 5. Olympic is unaware that “4” comes before “5”. Pastel and/or 1 is virtually a pure white and used for the lightest of colors. The others are slightly color altered from white and more translucent than pastel. These are used for succeeding deeper colors. All of this comes to neutral, 4 and/or 5. These are clear and used for (mixing) the darkest colors. In the can they are somewhat opaque but dry more or less clear.

    Now comes the testing. I bought 4 oak exterior doors. Each door was given one coat of the same MinWax Stain. On 3 of the doors, I applied 2 coats of “base” to the 6 sides of each door (3 coats on the top and bottom edges). Each of these three doors had a different type of exterior neutral, 4 or 5 base. The fourth door was finished with a consumer “spar” varnish from my local friendly paint/hardware store. The bases for the 3 painted doors were an exterior semi-gloss acrylic, an exterior semi-gloss oil-based polyurethane floor paint, and a semi-gloss oil-based trim and siding paint.

    The doors were set up, slightly inclined, in mostly direct sunlight under a pecan tree in the backyard. (My wife just loved that one.) Daily, the sprinklers managed to hit the doors. The birds in the pecan tree used the doors for target practice. And, yes, the dogs did anoint the doors on a regular basis. My blonde Cocker, Zazu, was particularly enamored with the doors. Over the course of the test the doors experienced lots of Texas sunlight, rain and snow. The temperature went from below freezing to over 100. The advantage to the inclined position of the doors was the snow, ice, water from the sprinklers and the rain tended to collect in the raised panel areas. I feel these doors were subjected to far more severe environmental conditions than would be expected from normal use.

    The results were interesting. The “spar” varnish (initially) looked fabulous; but, after about 2 weeks it began to develop small cracks. In rapid order the door began to turn black, started to mold and the smell was enough to knock a buzzard off of a manure wagon. The water-based acrylic is milky in the can like a water-based poly. It dried to a more or less water clear surface but was a bit cloudy. It tended to wash out the stain a bit. Over time it became cloudier and ultimately become almost white. But, it remained solid and protected the wood. The oil-based bases are also a bit opaque in the can but dried to a clear finish that is almost identical to a spar varnish – they added an amber tone to the doors. Both the oil-based poly floor paint and the oil-based trim and siding paint remained “clear” over the entire test period.

    The testing came to an end with a bit of encouragement. My wife said something clever like,”Get those damned doors out of the backyard!” She does not understand science. The floor poly had some minor checking and a thinned coat of the same base over the surface made that disappear. The door with the oil-based trim and siding paint was perfect, other than it had lost a bit of the gloss.

    So, I am with Bob – paint the door. My preference is the oil-based products. If you are predisposed to a water-based use an acrylic rather than latex.

    One thing you will find when you go out shopping for your product is a lack of knowledge on the part of the salesperson. Not many of these folk are aware that their neutral or 4 base will dry clear. If you want to have some fun, spring it on them. They will suggest you are full of Donkey Dust. Ask them to shake a can and put some on a stir stick. Dry it and voila, it is clear.


    One final admonition; if you decide to try the paint solution you must understand that you are applying it like varnish, not like paint. Use a good natural fiber brush, keep your coats thin, (emphasis added; keep the coats thin! We recommend thinning with paint thinner to improve flow-out and leveling.) and brush the paint-base out into a thin, uniform film. If you apply the paint-base too heavily you will get a cloudy finish.

  • woofy302

    Another finish that should be tested is marine varnish. It’s supposed to tolerate the sun’s UV rays very well.


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