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My first canvas job

Discussion in 'Wood and Canvas' started by Treewater, Mar 15, 2010.

  1. OP
    OP
    Treewater

    Treewater Wooden Canoes are in the Blood

    Thank you Fitz and yes Greg, keels are going on. Excuse my attempt at humor but I still must question, did I really have to add that weight, the filler? Would the canoe paddle just as well without it?
     
  2. Greg Nolan

    Greg Nolan enthusiast

    Tim --

    The use of a filler in the canvas covering certainly adds weight, but it also adds considerable durability.

    I would be interested to know just how filled canvas came to be developed and used for canoe covering, and who did it first. Canvas-covered wood canoes were developed at just about the same time as linoleum was introduced into this country, in the 1870's, and the make-up of linoleum and filled canvas are quite similar. The people who developed canvas covered wood canoes were tinkerers and innovators, and it is not surprising to me that they would have looked to other technologies of their time to improve upon their idea of replacing birch bark with canvas.

    Real linoleum (not the modern sheet vinyl commonly referred to as linoleum) is canvas filled and covered with linseed oil mixed with various filler ingredients -- pine rosin, ground cork dust, wood flour, mineral fillers such as calcium carbonate -- were all tried at various times, in various combinations. http://en.wikipedia.org/wiki/Linoleum . It seems that there was quite a bit of experimenting in England and this country with how to make a durable material from canvas and linseed oil.

    Also, floor cloths made from canvas painted with (linseed) oil-based paint had been used in this country since at least colonial times to protect floors, and light-weight canvas or linen fabric coated with linseed oil -- oil cloth -- was commonly used for waterproof table cloths into the 1950's. I remember as grammar school student in the 1950's that I and my classmates were required to have a piece of oil cloth to cover our desks at lunchtime. Today vinyl has replaced oil cloth, just as it has largely replaced linoleum. Linoleum itself, after its introduction, quickly replaced floor cloths of painted canvas, which had been in common use in houses to protect floors since at least colonial times -- linoleum was much more durable.

    As you have experienced, simply painting a canvas covering produces a water-tight hull skin. And the canoe would probably paddle just about the same without the filler. But filled canvas is much more resistant to abrasion and tearing, just as linoleum is much more durable than a simple oil cloth or a painted floor cloth.

    Greg
     
  3. OP
    OP
    Treewater

    Treewater Wooden Canoes are in the Blood

    Thank you Greg,
    Interesting comparison to linoleum. I wonder who else may have an opinion. I wonder if anyone has done, as Trailcraft, skipped the filler and just painted.
    Tim
     
  4. Greg Nolan

    Greg Nolan enthusiast

    Tim --

    About painting without a filler, I checked a few books I have, and found the following, for what it might be worth:

    English author Percy Blandford, in Canoes and Canoeing) (1968) says only to paint the canvas on a SOF canoe with two coats of top paint.

    George Putz in Wood and Canvas Kayak Building (1990) says that you must “kill the weave” by painting with two or more coats of “a high-grade flat-white paint and moderately add extra filler [chalk powder] and dryer to it,” after which you should sand smooth and paint with your colored paint.

    The instructions of author/designer R. O. Buck in the Popular Mechanics Build a Boat for Pleasure or Profit (1941, reprinting a 1938 article) for the Popular Mechanics canoe, says to “apply a coat of canvas cement over the entire surface. When dry, sand smooth and finish with one coat of deck paint and one of flat color after which it is again sanded and varnished.” There is no further identification of the “canvas cement” except that earlier there is an instruction to apply a coat of “waterproof canvas cement” to planking as part of the canvasing procedure. This cement could be Ambroid, or it could be Jeffrey’s Special Marine Canoe Glue which, in advertisements including one in the 1910 Boy Scout Handbook, make a claim that it is the “best filler for canvas.” Jeffrey’s seems to be a mixture of India rubber, naptha or benzene, and shellac.

    The Mechanix Illustrated (date unknown – probably 1940’s or 50’s) plan and instructions for building a small SOF kayak called Canvasback call for three coats of outside enamel, after an optional two coats of clear dope (apparently airplane dope) meant to shrink the canvas.

    Greg
     
  5. OP
    OP
    Treewater

    Treewater Wooden Canoes are in the Blood

    Greg,
    Thanks for the research. I need to ask the general group and i think i will start a new thread. i've searched the indexes and can't find much. Lots how to fill little, on why to fill. My general experience is that skin on frame flexes a lot when you hit something. I've gone over a lot of rocks and stumps particularly with sof. My only puncture was a kayak sof that was fiberglassed as well. the fiberglass did not flex on a stump and it punctured. Only one I've had. But the backing of a cedar plank is another matter. Not much flex there. Maybe I can get an answer.
    Tim
     
  6. Dan Miller

    Dan Miller cranky canoeist Staff Member

    Why fill? Three reasons...

    1) smooth surface = less drag, more efficient paddling. need something with high body to fill the weave of canvas

    2) abrasion-resistance - you want high resistance to scratching, puncture, etc. hence the use of silica.

    3) mildew resistance - mildew rots canvas, white lead kills mildew. 'nuff said.

    Still maintains enough flexibility over a solid cedar hull to resist cracking.

    Canvas over stringers (skin-on-frame) is a different ballgame altogether.

    While white lead is getting harder and harder to get, and has inherent health risks, it is hard to beat traditional filler (there are unleaded recipes). There are other alternatives that address these three goals, including Ecofill and pipe lagging compound.
     

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