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Finishing Prep

Discussion in 'Wood and Canvas' started by chipfitzgerald, Jun 27, 2018.

  1. chipfitzgerald

    chipfitzgerald Curious about Wooden Canoes

    I'm at the stage where I'm ready to start finishing the interior of my OT Charles River. What is the consensus for wood preparation prior to the of applying the multiple coat spar varnish? I've read some people use linseed oil or linseed oil blended with this and that while others simply use thinned varnish. Regarding thinned varnish, has anyone had experience using Danish oil?
     
  2. Andy Hutyera

    Andy Hutyera The Red Canoe Guy

    Danish oil aka Watco, aka, Fornby’s is basically a mixture of oil and varnish probably with some thinner and Japan dryer thrown in. It is primarily used as a furniture finish. I personally prefer an initial coat of orange shellac. Almost any finish, especially varnish, bonds to the shellac. The shellac gives a very nice warm color to the ribs and planking. Not sure what the advantage of an initial coat of Watco would be.
     
  3. Dan Miller

    Dan Miller cranky canoeist Staff Member

    Years ago I worked on a canoe for a customer who subsequently finished the interior with Deks Olje. Looked great, but I don't know how it held up in the long run.

    It is hard to go wrong with the simple schedule of sanding the interior to 220g, first coat of good, traditional spar varnish thinned 50%, second coat thinned 75% and the remaining coats thinned 90%. Use the manufacturers recommended thinner.
     
    MGC likes this.
  4. dtdcanoes

    dtdcanoes LOVES Wooden Canoes

    Dan....... do we mean thinned 50, then 25, then lastly 10 % ?
     
  5. Dan Miller

    Dan Miller cranky canoeist Staff Member

    Yes, yes we do. Sorry for the confusion - no one is more confused than myself. :rolleyes:
     
  6. OP
    OP
    chipfitzgerald

    chipfitzgerald Curious about Wooden Canoes

    Maybe I wasn't clear... I read about people applying a "canoe soup" before starting the finishing process. What works best for the canoe soup? Would Danish oil work for this step?
     
  7. Dave Osborn

    Dave Osborn LIFE MEMBER

    Never heard of canoe soup. You may be thinking of applying linseed oil to the hull and interior.
    If so, a search of this forum for “linseed oil” will give you all the info you need and a whole lot more.
     
  8. mccloud

    mccloud Wooden Canoe Maniac

    Several years ago at Assembly there was a forum of canoe builders, one of whom was Geoff Burke, and it was from him that I heard the term 'canoe soup' used. What he said basically was that he applied sufficient coats of canoe soup (maybe gunwales, decks, etc. but probably not entire hull, I'm not sure) until no more would be absorbed in a reasonable time. The recipe he gave for canoe soup or boat soup was turpentine 3/ boiled linseed oil 1/ spar varnish 1/ tung oil 1 parts by volume.
    I have used this on maple gunwales, decks, thwarts and like the way it handles, but you can't be in a big hurry. It takes time to soak in and will remain sticky for several days. However, don't leave it as a final finish, or black fungus will get on the wood. Finish with a few coats of spar varnish, as usual. If I have miss-stated what Geoff said, I hope he jumps in here and corrects me.
     
  9. Dan Lindberg

    Dan Lindberg Ex Wood Hoarder

    You might be confusing operations.

    For years the prevailing thought was to soak the wood in a mix of linseed oil/thinner, but that was to put "life" in old, dried out wood, not as a prep for varnish.
    The current thoughts on this are mixed.

    As for prep'ing for varnish, IMO, it's tough to beat what Dan said above.

    I am intrigued with the suggestion of using shellac as a base.

    BTW, in other circles, boat (canoe) soup is used for preserving the wood from rot, and in addition to the items listed above, coal tar is also mixed in.
    Unless you want a very dark canoe, I wouldn't recommend it. :)

    Dan


     
  10. Todd Bradshaw

    Todd Bradshaw Sailmaker

    If I wanted to prep with oil, I would use Deks Olje #1, following the directions on the can for applying multiple coats, wet on wet. It will be dry in a day or two, unlike linseed and it doesn't turn back in time like linseed oil can and does. However, I'm not at all convinced that such a base for your varnish is a great idea or likely to be an improvement. I once had an Old Town Trapper in my store and wasn't thrilled with the interior finish on this particular canoe. I called the factory to complain and was told that it had the "usual" schedule of finishing for all of their wooden canoes - one varnish coat thinned 50/50, followed by two coats at full strength. Granted, you can certainly improve the cosmetics with a couple more coats than they used, but in general, that scenario worked pretty well. I don't see much reason to do something different or add additional materials to the mix. As for thinning, heavily thinning the first coat is to improve penetration a bit. Thinning following coats should be done if and when it is needed to improve the way the varnish handles - on that particular day and in those particular conditions with that particular brand and type of varnish. If the brush is dragging and the stuff isn't flowing well, by all means, adjust it a bit, but it is better to adjust paint or varnish to the job as needed than just blindly or automatically.
     
  11. MGC

    MGC Paddlephile

    I'm with Dan on this but I also am with Andy. Depending upon the hull I will either use a thinned varnish for the first inside coats or I will use shellac. Rushton was known to use shellac on rush orders as a base and also on rush orders. These first coats are followed by multiple coats of good quality spar and again, depending on the hull are followed by one final coat of Epifane Matt finish...I don't like old hulls to be so shiny that they attract crows.
    "Boat soap" so called is applied to the outside of the hull. Everyone has their own recipe. This has been discussed here often..search and you will find many opinions and blends.
    I use a blend of linseed oil, turpentine and mineral spirits. I apply it while it is hot. It will soak in immediately and then cure in 24 hours. If you apply more it will not soak in as well and may take a while to cure...moderation is a good idea. I have never seen this blend blacken.
     

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