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Thread: Water Proofing wood

  1. #1

    Water Proofing wood

    Someone replied to a thread I posted elsewhere and said "Ask those guys over on the Boat Building forum - they know about water proofing wood. SO here I am.
    This was my original post:
    I am building the wood bed for an old pickup.
    I have oak ready to put a finish on. I believe it is red oak.
    I sanded it with 80 grit and then finished it off with 220.
    I want to use 100% tung oil but don't know much about it. SO I guess I need someone to tell me some about it.
    From some info I "read" you can put the first couple coats on with it thinned 1:1. (I assume with it thinned it will penetrate the wood better??)
    I have no clue if the tung oil will color the wood or how much. I assume the more coats = the more color.
    SO there you have it - that's pretty much the limit of my knowledge.

    I want to use tung oil to avoid using any sealer that may chip / peel off later on in years to come forcing me to have to take the whole bed off and refinish it. I heard the the more coats the nicer it looks and more waterproof it makes the wood.
    I heard you can keep adding tung oil to put moisture back into the wood instead of having to take it off and refinish it on down the road?? True??
    I'm working on making a street rod / show truck and want a super finish on the bed and something water proof.
    Also I was thinking about actually using some sort of sealer on the bottom of the boards that will be exposed to water; mud; grime, etc. I thought maybe it might help prolong the life??

    There you have it - feel free to correct any of my misconceptions and add any info I need.

  2. #2
    Welcome aboard. We mostly like to help, but ....

    No one wants to touch this one, because no one wants to throw rocks at a Newbie. It's a tough question and one with no easy answers, but I'll take a shot:

    1. Red oak is not very rot resistant, so sealing the wood is a good idea. Tough to do well, however. Red oak would not be my choice for this duty. [I like Ipe for this, for decks, for other outdoor stuff. Hard to work, but worth it.]
    2. Tung oil does not produce a water proof coating; it will be somewhat water resistant, but only for a short while. Not a good choice, IMO.
    3. To make any piece of wood "waterproof" requires sealing all surfaces, top, bottom, ends, edges, screw/bolt holes and any other wood surface. If water can get in, it will.
    4. Durable waterproof coatings in my usage are limited to two part epoxy encapsulation, e.g. WEST SYSTEM Epoxy and an overcoat for ultraviolet light protection of two part marine polyurethane, e.g. Interlux Perfection Plus, Lots of epoxy guidance on the West System site. Good idea to check it out.
    5. The polyurethane is pretty good stuff, but it will need maintenance: repair any scratches promptly, lightly scuff-sand and overcoat every two or three years (when you see any yellowing develop). If you do a good job and stay on top of it you won't see any peeling. I know bright finished boats that have epoxy/urethane coatings that have been maintained for as much as 25 years and still look great.

    Other folks may have other ideas for you but these are the best I know.

    Good luck!
    Fair winds and following seas,
    Jim Waldron

  3. #3
    Join Date
    Jun 2013
    US Virgin Islands
    Blog Entries
    Well, they do use Tung Oil to seal Chinese Junks, but then again, they're just Junk. (nyuck nyuck) But seriously- that is what they seal them with to waterproof them. It wouldn't be my first choice. Here are my thoughts:
    - Your post suggests that maybe you think tung oil will stay oily, and it won't. It cures hard like other finishes. I may be misinterpreting your comments about recoating to keep the moisture in the wood. If you sanded and then recoated, perhaps, but just recoating if the old coat is still hard won't necessarily rehydrate the wood.
    - Jim's idea to coat with epoxy would work, but even with a UV inhibiting coating, it will eventually degrade with UV. Also the idea of having an oak floor is that the oak takes well to scratching. Coating it with fiberglass would be putting a less abrasion-resistant coating over it. I wouldn't go that route, especially in a truck bed that will probably get a lot of sunlight.
    - I would use Goldspar or similar spar varnish. That's what my buddy who restores street rods has done in the past, and it held up well, although this was more show than go, and I doubt he was throwing firewood in the back. Goldspar has an amazing golden hue (hence the name) and glossy finish. The gloss has a UV inhibitor. (Matte and semi-gloss doesn't, and I always assumed it was something with the makeup of the UV inhibitor.) It's going to scratch, but all finishes will scratch, including tung oil.
    - Another idea is Minwax Polyurethane floor varnish. It is available with a UV inhibitor, and it holds up to my 5-year-old, which means it is as durable as kryptonite. :-) I used it on my floors. Seriously- it's tough stuff.
    - Whatever you use, varnish both sides of the wood. I am assuming this is the type of bed where it's wood strips laid in metal channels and bolted down. Water will get under them, so certainly varnish both sides.

    By the way, if you see something labeled "Teak Oil," it is likely a mixture of tung oil, linseed oil, and possibly even mineral oil. It's not UV resistant. You will get a similar result with it as if you used just boiled linseed oil.

    What I use on boats is either Goldspar or Epiphanes varnish with UV inhibitor. Thin it per directions with the recommended thinner. Of course they will usually recommend their thinner, which I think for Epiphanes they call it 333 thinner, but read carefully because they usually also offer recommendation for readily available (i.e. "cheaper") thinners. I will say that their 333 is good quality, but it's expensive. Also follow directions closely for coating times- I believe they recommend 12 hours recoat time for my weather, which is 80F. If you're in colder climates, the recoat time can go as long as two days. It's very slow drying stuff. Whatever you do, don't get hasty, especially with your first coat. Also, I do believe they recommend 30% thinner for first coat, but check me on that. I have thinned it even more, depending on the density of the wood, and then I thin the next coat a little less, then the next even less, and so on until I'm pretty much putting it on straight. Put six to ten coats total. Sand between coats.

    ...and please post pictures. I have a love for wood beds in trucks.

  4. #4
    well Shucks - I originally wrote a post but now I see for some reason it didn't post. Let me see if I can put my thoughts back together.
    Let me toss out what I said when James first replied.
    I appreciate your response. I can understand the concept of not wanting to throw rocks.... thanks
    As far as my project. I had red oak available left over from something else; so that's what we used. It is cut; shaped; dry fitted and sanded ready to finish. SO I guess I'm kind of locked into going that way.
    As far as rot; I am disabled / retired so the truck "generally" won't be out in the weather much and it stays in a climate controlled garage when at home. SO I am not expecting rot to be much of an issue if I get a good finish on the wood.
    I have cut for side boards; the bed and also the running boards. Maybe I'll post a pic of the running boards if I don't forget.
    As far as tung oil; I appreciate the info provided about it. It sounds like I may want to go another route.
    I checked into the West System and that $83/quart is a bit pricey at first glance. I figure I got 100 Sq Ft to cover (one coat). It looks like a quart will cover about 100 sq ft - so I guess each coat would cost me $100. Not sure how many coats I'd need. OH and I forgot to add in the cost of hardener and shipping.
    Someone else told me about something called "Old Masters" I saw a Gel Urethane; a Tung Oil Varnish; a Spar Marine Varnish and a Spar Urethane SO I was going to ask if one of those might be a better way to go.

    Then I see where Malcolm has now posted. I see he also mentioned a Spar and varnish. SO maybe that is more the way to go. I appreciate the recommendations. I'll have to do a little research on this "Goldspar" or "Epiphanes". It could be it is something like what I saw just from a different company. Be Nice to fins this somewhere local to save on shipping. I live close to Lake Lanier (In Ga) lots of big boats around here so maybe I could mull around and find a place to get something.
    As far as time for it to cure. No issue there. I want to take whatever time to do it right; and I am a couple months away from having the trcu ready to put the wood on. This is something to keep me moving along to do when I'm not at the shop working on the truck itself. I have to do the wood; make door panels; etc.
    Oh If I can figure out how I'll post a pic of the running boards I built. I used the old steel boards to make a pattern for a frame. I also will add a pic of a SMALL20190210_140926.jpgSMALL20190206_131741.jpg small section of the bed boards.... Well looks like I ALMOST did it right LOL

  5. #5
    Join Date
    Jun 2013
    US Virgin Islands
    Blog Entries
    That's going to be a nice truck bed! I've been to Lake Lanier- nice place. I'm sure you will find it somewhere in your area. At one time, Home Depot sold Epiphanes. It may be only sold in certain areas, i.e. coastal stores, but worth a try.

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