Vinyl is kinda a generic name for a family of soft flexible plastics. The base of many of these is PVC or PolyVinyl Chloride. (CPVC, or Chlorinated PolyVinyl Chloride is related, too) Depending on how this stuff is mixed, and there are lots of recipes, it can be stiff or flexible, opaque or transparent, clear or tinted. You see a lot of stiff PVC and CPVC tubing being used for plumbing. Just like the old LP record albums, it is all "vinyl".

For our purposes we use mostly "vinyl" which is more flexible. It can extruded as a sheet of flexible material, or it can be applied to fabrics to waterproof them. There are two major ways to apply vinyl to fabric. One is to paint or soak the fabric in a liquid vinyl base which is then heated to set, or harden the material. Another way is to take a sheet of fabric and fuse it to a thin sheet of vinyl. Sometimes the process uses two thin sheets of vinyl and fabric is sandwiced between them before the whole deal is fused into a single sheet.

Problems for us come from the lack of uniformity in describing the materials. An 18-ounce PVC coated fabric might have a 2-ounce fabric core with the strength of cheescloth, covered by 16 ounces of very soft vinyl, or it could be a core of 14-ounce cordura nylon with 4 ounces of toughened vinyl to seal and waterproof it. And there are hundreds of possible variations with any given material weight. Get a sample and compare it to other samples to make an informed decision before buying any quantity. Or, go with something that has a tradename, or a reputable seller, or something which has been recommeded by other builders.

There are a lot of truck tarp materials on the market. Tom Yost has had good results with those he gets from Mauritzon, in Chicago. Others who have followed his plans have been happy with the results. It is tough stuff.

On the other hand, many people are using clear vinyl which has no fabric core to reinforce it. Without the fabric it stretches more easily, and it can be cut more easily--but it is widely available at Wal-marts around the US at a low price, and it looks really cool to have a clear kayak skin covering a nicely finished wood kayak frame.

There is a cost factor, and it is not always easy to calculate. The cheapest decent skin is the thickest clear vinyl from Walmart. It is a little over $4 a yard and should last a few years. next would be a cloth skin of cotton canvas or duck, polyester, or nylon. After paying for the cloth you have to coat it with a waterproofing material. If you are doing this at home a very common choice is latex exterior house paint; it is cheap and easy to use. For years people have used oil-based house paints on cotton duck fabrics. With the synthetic fabrics they use urethanes, polyurethanes, neoprene and hypalon.

The precoated fabrics cost more, but you get a very good product for your money. You save on the cost of paint and fabric fillers to waterproof the skin. If the core fabric is strong the skin will be strong.

With rare exceptions, Vinyl-coated fabrics are made in factories. Whatever fabric they use for a core can be a secret, or well documented. Vinyl is not easy to apply at home. It is difficult to buy small quantities, and hard to get it to set correctly without an oven. or a bank of heatlamps. If you want to try it, I'd suggest getting a vinyl-based silkscreen ink --also called a Plastisol-based ink. It can be applied with a brush or squeegee, and will eventually dry to the touch, but it needs to be heat set to cure the plastic.

Besides Mauritzon, McMaster Carr sells vinyl-coated fabrics, as well as hypalon-coated fabrics. Their catalog is at www.mcmaster.com.

Hope this helps.

PGJ