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Thread: Tar on Canvas Canoe - Suggestions?

  1. #1
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    Default Tar on Canvas Canoe - Suggestions?

    I have finished the frame of a traditional curach (Irish skin-on frame fishing canoe), and my thoughts are turning to the skin. Traditionally, the canvas was covered with tar, which made the boats watertight. Traditional tar is nearly impossible to come by (I've read that some people use a mix of coal tar and pitch), and as a result we have been using bitumen paint instead. The problem with this is, however, that it causes the canvas to shrink and tear away from the frame. It also has a dull colour, compared to the hard glossy cover of the traditional tar.

    Would anybody have any suggestions for an alternative to the traditional tar and the bitumen paint? Or could I do anything to the bitumen paint to stop it contracting so much?

    Thanks in advance for any help!

  2. #2
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Can't you get it from Sweden or Norway?

    http://www.solventfreepaint.com/pine-tar.htm

  3. #3
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Try contacting Narrow Boat repair yards or these folk at Ellsmere Port https://www.nwm.org.uk/HeritageBoatyard.html. I suspect that wooden narrow boats and barges are still finished with tar. They may be able to offer advice.
    It really is quite difficult to build an ugly wooden boat.

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  4. #4
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Thanks for the reply Dave,

    I wonder if Stockholm tar would do the job?

    https://www.deesidecountrystore.ie/h...caAi80EALw_wcB

    Would it create a waterproof barrier?

  5. #5
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Quote Originally Posted by Peerie Maa View Post
    Try contacting Narrow Boat repair yards or these folk at Ellsmere Port https://www.nwm.org.uk/HeritageBoatyard.html. I suspect that wooden narrow boats and barges are still finished with tar. They may be able to offer advice.
    Thanks for that - I'll try them.

  6. #6
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Are you preshrinking the canvas? In my experience with celtic craft we've often used black oil paint of various types and not had shrinkage issues, but the canvas was washed and dried hot multiple times before stretched onto the frames.
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  7. #7
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    Default Re: Tar on Canvas Canoe - Suggestions?

    What kind of tar?
    I don't think Pine/Stockholm tar will work, and my guess is that even if it does it will get washed out over time.
    Over here, the traditional way to make canvas water tight is to use linseed paint, but alkyd oil paint will probably work too. They do shrink the canvas but not too much, and I think that shrinkage can be avoided all together by coating the canvas with BLO or paint before putting it on.

    /Mats

    Elected Swedish Yourneyman of the Year 2019

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    Default Re: Tar on Canvas Canoe - Suggestions?

    Quote Originally Posted by Thorne View Post
    Are you preshrinking the canvas? In my experience with celtic craft we've often used black oil paint of various types and not had shrinkage issues, but the canvas was washed and dried hot multiple times before stretched onto the frames.
    I hadn't thought of that, pre-shrinking the canvas. There is a lot of canvas involved (the boat is 24ft), but it will be cut into sections and sewn.

  9. #9
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Quote Originally Posted by mohsart View Post
    What kind of tar?
    I don't think Pine/Stockholm tar will work, and my guess is that even if it does it will get washed out over time.
    Over here, the traditional way to make canvas water tight is to use linseed paint, but alkyd oil paint will probably work too. They do shrink the canvas but not too much, and I think that shrinkage can be avoided all together by coating the canvas with BLO or paint before putting it on.

    /Mats
    Thanks for the reply. I think it was coal tar, mixed with pitch. Excuse my ignorance, but what is BLO?

  10. #10
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Quote Originally Posted by Tochta View Post
    Thanks for the reply. I think it was coal tar, mixed with pitch. Excuse my ignorance, but what is BLO?
    Boiled Linseed Oil.
    It really is quite difficult to build an ugly wooden boat.

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  11. #11
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    Default Re: Tar on Canvas Canoe - Suggestions?

    N.B.

    Boiled linseed oil is not linseed oil which has been boiled, it's linseed oil plus heavy metal salts as a drying agent.

    Builders merchants sell bituminous paint for waterproofing walls, commonly called "Black Jack".
    Creationists aren't mad - they're possessed of demons.

  12. #12
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    N.B.

    Boiled linseed oil is not linseed oil which has been boiled, it's linseed oil plus heavy metal salts as a drying agent.

    Builders merchants sell bituminous paint for waterproofing walls, commonly called "Black Jack".
    Thanks for that. I can get Black Jack easily. I might as suggested pre-shrink the fabric, then coat with black jack.

  13. #13
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Tochta how traditional do you want to be? Cotton duck with coal tar is certainly not older than 150 years. Before that it was probably home made hemp or linen cloth with linseed oil, and before that greased leather. Nowadays you have the added choice of nylon and polyester fabrics and modern coatings. Cotton duck can be bought sanforized, that is preshrunk. Certainly the most simple way to do a skin would be to use black PVC. You can find it with acrylic coating, that will give you the hard glossy finish you want.

  14. #14
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Quote Originally Posted by Rumars View Post
    Tochta how traditional do you want to be? Cotton duck with coal tar is certainly not older than 150 years. Before that it was probably home made hemp or linen cloth with linseed oil, and before that greased leather. Nowadays you have the added choice of nylon and polyester fabrics and modern coatings. Cotton duck can be bought sanforized, that is preshrunk. Certainly the most simple way to do a skin would be to use black PVC. You can find it with acrylic coating, that will give you the hard glossy finish you want.
    Thanks for the reply, I have the cotton duck already, so am using that (people are using ballistic nylon instead nowadays, as it doesn't shrink as much). True also that canvas has only been using for the past 150 years - before that it was hide, usually horsehide, but I'm not going to go that traditional!

  15. #15
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Real tar is readily available in roofing supplies shops, comes in 40kg cardboard kegs and needs to be melted in a tar boiler to use.

    Nasty stuff, causes bad burns.
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  16. #16
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    Default Re: Tar on Canvas Canoe - Suggestions?

    If the cotton duck you already have is unsanforized (you can test for that, sanforized material should strech less than 1% after washing) you need to wash it at 90C after presoaking, then iron it at the highest setting after it dries.
    Normal oil paint is what I would use for waterproofing.

  17. #17
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Stockholm Tar can be mixed with melted bee's wax and a bit of turpentine. It makes a nice waterproof coating for all manner of natural fiber products. It does not wash off easily and lasts a very long time! We used it on the hemp dead eye lanyards on the Sea Witch and Mayflower ketches when we rigged them. It held up very well and allowed the lanyards to remain flexible. It should do the same for cotton canvas.
    Jay

  18. #18
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    Default Re: Tar on Canvas Canoe - Suggestions?

    Having recently used a few coats of alkyd paint over the acrylic 'canvas' mast boot on Blow Fish (a perigee) it looks like modern fabrics with single pack boat paint could work. Seems very watertight and the fabric takes the paint nicely. So far it has remained somewhat flexible, but only time will tell if cracking paint becomes an issue.

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