: Wal-Mart has canvas for only $4.44 yrd. Has anybody used their canvas? I have
: no idea of the weight.

: Do I have to prime the canvas before painting it?

The canvas I've seen at my local Wal-Marts appears to be the same as the 10 ounce canvas I bought at the local Jo-Anns fabric shop. Note, this is 10 ounce, NOT #10 canvas.

For comparison, Sears used to make their toughest blue jeans from 11 ounce denim, and the usually spoecified #10 duck is about a 15 to 16 ounce fabric. The weights refer to 1 square yard of the fbric. The heavier fabrics get that way usually by being thicker -- which in our world means that they would be a bit more puncture and scratch resistant.

I skinned the bottom of my test frame with 10 ounce canvas three years ago, and let it sit outside, thorugh rain, snow and sunlight. The coating on it was three coats of white elastomeric roof coating, on the outside. (snow coat, or snow roof -- by now I can't remember the brand name) What I did not do was coat the inside of the fabric. After a year the cloth developed a good case of mildew, and by the end of the second summer there was substantial rot, which was strangely located in the edges where the fabric was attached to the frame. I suspect that moisture trapped between the wood of the frame and the fabric fed the mildew. Other parts of the skin look darker due to the discoloration, but seem to be strong enough for use.

Scraps of fabric that were coated on both sides with the roof coating (sometimes this happens unintentionally -- yes, I do drip a bit of paint ) did not seem to be bothered by the mildew.

If I do this again I'd either seal both sides of the fabic with the roof coating, doing the inside before stretching it, or, after tacking on the skin I'd apply the roof coating to the outside first and let it cure, and then apply a mildew preventative to the inside. The problems with the second course of action is getting that mildew preventative into the areas that are tight, and need it the most.

This problem is shared with other brands and weights of cotton canvas, though.

Inside storage adds years to the life of these boats. Otherwise, at under $5 a yard, you can re-cover an 18 foot boat for about $30 every other year. At a cost of $15 a year for the fabric it is cheaper than a gallon of paint.

I painted a section of my test boat last year with some marine enamel. I adhered nicely to the roof coating, but it was not as flexible, and cracks developed when the enamel was dry and the fabric was flexed. The cracks would not leak because of the waterproof layer under them, but they would look bad.

Wal-Mart had one other fabric which looked good. It was a polyester canvas, which looked like it was for window awnings. Tightly woven and brightly colored (I got solid blue) I though of using it for the deck. I doubt it would be waterproof enough as-is to be used for a hull, but it might be water repellant enough to work as a deck. Just as long as splashes bead up and run off, instead of dripping inside. If not, then I could coat the inside with my roof coating ( keeping the nice color on the outside) Or, I could coat it with a clear urethane.

Hopefully it would be a bit breatheable, and keep the inside of the boat from becoming a steambath. I think it was the same price as the cotton canvas.

So, is the material any good? Yes. But, being thinner it won't last as long, so you may need to re-skin the boat in 2 or 3 years. If you like the design of the frame you can chose to re-skin with a synthetic fabric, or a heavier, more expensive fabric at that time.

To stretch the life of the thinner material, apply a second layer -- a strip about 10 inches wide centered along the keel -- which is just set into a layer of wet paint or roof coating, and then painted over. The trapped paint will serve as all the adhesive you need to hold that strip on. The thicker keel layer will be more durable and resist scratches better than a single layer of thin fabric.

As for priming: Your first coat will seal the material and serve as a primer. If you want to thin it a bit it might soak into the fabric a bit more. After stretching the fabric over the frame you will have plenty of scraps to test different painting approaches on. Let your tests dry for a few days before you test them for durability and waterproof-ness. You can work on installing your seat, floor boards, backrest, etc. while you wait. when you are satisfied with your tests, put a few coats of whatever on the boat and paddle happily. You'll recoat it next year, and the year after, building up a thicker and thicker layer of paint on that skin. No need to put over 4 coats of the paint on this year.

Hope this helps.

PGJ