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Thread: Painting wet wood or canvas

  1. #1
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    Default Painting wet wood or canvas

    I had a couple of questions about the practice of painting boats. I know from reading up on canvassing decks that thinned paint is applied over canvas that’s been shrunk with boiling water. I gather this is done while the canvas is still very wet. Similarly, perhaps, I read that a pre-painting ritual for traditional wooden boats is to flood the boat and swell its planks prior to a fresh paint job.

    What are the considerations for painting over wet wood or canvas? Is there no worry that there will be poor adhesion, or is the theory that painting a boat like this is a part of regular maintainance and adhesion isn’t a great consideration?

    Also, with a painted canvas deck, how many coats of paint are applied after the first heavily thinned coat? Once the canvas and thin paint have cured is this then a deck that can be repainted for many years as regular maintainance?

    Thanks for any thoughts on this. I know this is very basic stuff, but it runs counter to my land- based carpentry training.

  2. #2
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    Default Re: Painting wet wood or canvas

    Once the canvas has been shrunk (being fastened before with copper tacks or monel staples,) it is then painted. The canvas is painted dry with thinned paint which will soak into the weave. it is not painted wet. The paint permeates the cotton and serves to prevent the cotton rotting.

    Boats should never be "filled with water to swell the planks." (Although I suppose an exception can be made if the open seam is low in the bilge and the bilge is only filled a bit.) The planks are engineered and fastened to accommodate pressure from outside the boat, actually to carry the entire weight of the boat and her cargo when in use. They are not engineered and fastened to withstand the weight of water inside the boat pressing outward. Filling a boat with water puts undue strain on the planking and can weaken and start plank fastenings. To properly swell planking, put the boat in the water, or, if hauled, to arrange a misting system, wet burlap bags, or the like, to provide sufficient ambient moisture to permit the planks to swell properly.

  3. #3
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    Default Re: Painting wet wood or canvas

    As #2

    The canvas is dry when painted.

    Never fill a boat with water to swell up the planking for the reasons given.

    Usually the best way to deal with a carvel planked hull that has dried out is (assuming the fastenings and caulking are in good order) to stop the seams with a soft stopping compound – times ago with a mix of red lead putty and grease – nowadays with a flexible bottom seam compound – and white lead putty and grease/flexible topsides seam compound above the waterline. Then paint the dry hull.

    Then launch the boat with sufficient pumping equipment, and as she takes up the soft stopping will squeeze out of the seams. If you hold her in the slings over a period this will help - or as we could do on the East Coast of England, moor her in a tidal mud berth.

    Even if you mist the hull or use wet sacking, you still wait until the timber has dried again before painting – for the very reason you ask - good adhesion.

    Cheers -- George
    To be truly free to live, one must be free to think and speak.

    A C Grayling

  4. #4
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    Default Re: Painting wet wood or canvas

    Guys, I beg to differ on the dry canvas comments. The canvas is painted with piss thin, oil based, paint right after the shrinking of the canvas has been done. The thin paint soaks into the wet canvas and locks the shrink in place. It should also be noted that the canvas must not have been, Sanforized, pre-shrunk, prior to being tacked down. This is an absolute must! Canvas that is used for boxing rings is sold in raw condition.
    Be sure to specify to your dealer that the canvas you need is the kind that will shrink when hot water is applied to it. Once the first coat of paint has dried, usually the following day, the next thin coat is applied. Only enough thin coats to give a uniform color are needed. This is to avoid filling of the canvas weave and only to color it. Other wise the canvas will loose its anti skid properties and not offer a non slip surface. Also, a canvas deck that is so filled with paint as to hide the weave will crack!
    Jay
    Last edited by Jay Greer; 09-07-2018 at 12:51 PM.

  5. #5
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    Default Re: Painting wet wood or canvas

    Thanks for the replies, Gents. I did assume that a boat would be in the water and allowed to fill as opposed to filled on land like a bucket.

    So Jay, is there any reaction between the oil paint and the wet canvas that either helps the coating or hinders it? I would assume the water would prevent the paint from penetrating, but maybe the opposite is the case. Are subsequent coats of paint used before use or is the single thinned coat it?

    Thanks again.

  6. #6
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    Default Re: Painting wet wood or canvas

    While there is no doubt that oil and water don't mix, the method I have described to you is the way Omar The Tent Maker, who made sails, tarps and sold canvas in Newport Beach Ca back in the 50's , explained it to me. And that is also the way we put canvas decks on at Carl Chapman Boat Works where I first went to work as a boatwright. So, all I can say is that I don't no much about boats but the guys I worked with and learned from did. The thin paint does soak into the damp canvas and prevents build up, a condition that makes canvas paint sick! All that is needed is enough thin coats to creat uniform color. In the two photos here, the first coat has dried and the canvas is blotchy. The second photo shows the coverage after the third coat which was enough to create sufficient coverage. Scrubbing the canvas with a soft brush and DAWN DISH SOAP removes the jet fuel and other crud that is dropped from aloft onto the canvas. After a season or two of this the paint will again look blotchy and so it is time for another coat. No sanding or other prep is needed once it has been well scrubbed. Incidentally for teak decks. Dawn and sea water for scrubbing will clean the teak nicely. Afterwards sprinkle on a bit of CITRIC ACID and allow it to soak for a few minutes. Then rinse off with sea water.
    It helps to have a cedar bucket for that. Your teak decks will turn a lovely shade of pale!
    Jay
    Last edited by Jay Greer; 09-08-2018 at 12:52 PM.

  7. #7
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    Default Re: Painting wet wood or canvas


  8. #8
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    Default Re: Painting wet wood or canvas

    I sould add that the oil based paint that is used on canvasj should be semi gloss, exterior, house paint. This paint is designed to sluff off and present a new surface as it weathers and is scrubbed off. Because of this built in property, the painted surface does not build up and clog the weave.
    Jay

  9. #9
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    Default Re: Painting wet wood or canvas

    Thanks Jay, that boat is magnificent

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