scraping paint down to canvas

I'm waiting for wind to test my homebuilt sailing canoe. Meanwhile, this is a store bought sailing canoe. OT 150592, 1948 17ft with sponsons. It has several paint layers and I am scraping/sanding (and using an expensive respirator). How much scraping and sanding is too much and how much is too little. See pictures.

 

For a functional finish (as opposed to a super high-gloss finish), if the red paint is holding tight and not flaking off, I would just sand until smooth -- I would not try to remove all the old paint. Two coats of a good paint will cover even the red, although if you use a similar red paint, any future scratches will be less visible than if you use a different color which, when scratched, may have the red remnants showing.

My 2 cents.

 

order of finishes?

Thank you Greg. That is two cents more than I have.
This being my first canvas on cedar renovation I am trying to understand the order of the finishes applied. The Canvas appears sealed with a clear finish. Then a coat of red paint. Then a thick white coat of something appearing to be a filler on top the red paint. Then another coat or two of final red paint. Naturally, a poor coat of red put on much later.
the fellow I got this from had a marine repair shop and said "the filler is 'dusty'." He said to fix it with "epifanes" or "pettit high build primer."
Never heard of them.
I have the wales off and while everything is in good shape I wonder if I should treat the rib tips with something before I put the wales back on.

 

As I understand how things are usually done, a filler is applied directly to the raw canvas--filling in the weave to makeg for a smooth base for paint--followed by a few coats of paint, or perhaps primer and paint.

A high-build primer is intended to fill in very small scratches and other very small dings, and to be easi lysanded smooth. May be useful when dealing with an aold paint finish that has a bit of very fine paint cracking, though the risk there is that the paint may be getting ready to flack off.

I'm not sure how to approach a "dusty" filler -- but I think that if I had the surface basically smooth, I would try an oil-based primer, then a couple of coats of oil-based paint. If your surface still needs a bit a smoothing, a coat of high-build primer, sanding, and then primer and paint.

If the "dusty" filler is actually beginning the process of disintegrating, you may really have to replace the canvas. But since you've gone so far to prep the surface, there is little to be lost at this point by doing a final sanding/smoothing, and then priming and painting.

Some primers aren't much more than thinned paint, while others actually help with binding the paint to the surface -- and I don't know how to tell one from the other. If you have a good sound surface, priming is often not needed. But since you probably want to put a few coats of paint on, the first might as well be the primer for the paint you use.

Epiphanes is a brand of marine varnish and paint -- I have no experience myself with it, but it has a mixed reputaion on the WoodenBoat magazine forums, and I understand that, like most "marine" finishes, it is expensive.
Lots of folks on these forums, and some on the WoodenBoat forums, think the expense is needless, and that other good exterior grade paints do just fine on a canoe. Your dime, your call.

I guess this make it my 4 cents, now.

 

Russ Hicks' article

A recent Journal article by Russ Hicks, Michigan Chapter covers this and may be very helpful. I think it's the Feb '10 issue. Russ rejuvenated an old canvas.

 

I'm may be wrong but in the pictures it appears that the wood hull is covered with fiberglass and not canvas. That would explain the "clear finish" and also why it would be "dusty". If this is the case you can sand the hull fairly hard with a orbital sander and paint it directly with your exterior grade finish paint of choice. Any weak areas in the fiberglass cloth can be filled with more fiberglass and rough spots can be smoothed out with a bit of auto body filler.

 

canvas or fiberglass

Thanks Rollin. I am a little concerned about that but it does seem to be the original canvas with one inch tacks holding it. Still, the canvas gives the appearance of being treated first then filler after paint. Doesn't seem to make sense.

 

filler-paint-filler-paint

I have most of the paint and filler off this canoe. I believe the confusion is that it was filled, painted, then filled again and painted again. I do not know how the factory operated but it does seem they sent it back for a re-fill and paint after it was first done. This may have caused the later problems. Maybe the factory will warranty it.

 

This article concerned me. The author seemed somewhat cavalier about sanding lead-based paint. Although he wore a dust mask, as I recall, he evidently made no attempt to contain the dust. We're talking serious toxic stuff here and I would NOT follow his lead in this respect.

I also questioned his rationale for renewing the canvas on the grounds of preserving a historical aspect of the canoe. I think the canvas can be viewed as a long-range consumable, kind of like tires on a car. I don't think that collectors of antique cars (or at least the ones who actually drive them) go to great lengths to keep the original rubber -- they replace it when necessary. Especially if the canoe canvas contains a toxic substance, it seems to me that replacement is better than renewal.

 

good points

Two good points Bob. I now have a garage floor full of sanding dust and that did occur to me, I view that dust with suspicion. I think I would go with changing the canvas as you suggest. In this particular case, it is a sponson canoe and merely to avoid the work I am trying to save the old canvas.
But for future work, I think changing the canvas is the way to go, except for the sponsons, I think it would be easier. I have several days into sanding and now prepping this old canvas. Could have put new canvas on a lone canoe in an afternoon.
My thoughts. Tim

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