> I have found a place where I can get a complete gallon system for $15 Is
> it worth it? what are the properties of the stuff? How does it compare to
> the moden epoxies like west system?

This is the classic fiberglass resin that has been used in almost every ``fiberglass'' item you can buy. It has been around for a long time, and has a long history of use in boat building. In the 2nd version of his book on building strip canoes. Gil Gilpatrick mentions his personal experiences with changing from polyester to epoxy resins. I am guessing that in his first version he mentioned ONLY polyester resin. I believe the third incarnation of this work is now on the market. If so, I'd be interested in seeing if he even mentions polyester anymore. The trend is towards epoxy.

David Hazen's book on strip building canoes is old enough to mention ONLY polyester resin. If you decide to use this stuff I'd suggest you get a copy of his book as it gives a very nice description of how to work with the materials -- and he had full size plans for a couple of strip-built kayaks that come with the book.

On most wooden boats polyester has provided a solid, waterproof, sheathing that extended the life of old wooden boats by decades, and made wooden boats practical home-workshop items. Red cedar is not a particularly good base for it, though. My sources say that there is a problem with resins in the wood interfering with the bond of the polyester to the wood. Apparently, this was well known years ago, and older wood strip canoes (not many people building kayaks then) were made from White Cedar. Pine is another good wood to build from if you are using polyester resin.

Since pine is so cheap and easily available, and the polyester resin so cheap, the combination was well known for making ``cheap'' boats. Unfortunately ``cheap'' may not be the best label to put on a well crafted boat. My take on this is that the boats were inexpensive to make, so people assumed they were inferior. When people went to using cedar, and they had problems with the resin, they may have assumed it was the resin, and not the wood/resin combination.

By the way, the trick I have heard for using red cedar with polyester is to seal the cedar with a coat of sealing lacquer and sand lightly before putting on the first coat of polyester resin. The lacquer soaks in deeply, sealing the wood, and the polyester likes to bond to the lacquer. Or that is the theory at least.

A friend of my has built over 15 canoes from pine and polyester. He refinished the first one he built, when it was about 20 years old. When he did, he used epoxy. He (jokingly) said he was tired of refinishing boats every 20 years, and wanted to use something more durable. If you ask me, I'd say 20 years of use from an inexpensive resin is one heck of a good deal. If epoxy will last longer, then you`re looking at a service life of 30 years or more.

For many people, when dealing with such a span of time, they will tend to go with the more expensive materials. Their rationale is that the cost per expected year of use is very modest. For example: a boat built with $200 worth of cloth and resin that lasts 20 years is only $10 a year. One that costs $300 and lasts 30 years is also $10 a year. Therefore they want the more durable material up front. Either way sounds good to me. If you are on a tight budget then build with polyester.

Epoxy soaks into the wood and seals it from moisture penetration. Polyester sits on the surface and has microscopic holes (like Goretex) which permit water vapor to penetrate. This is a very slow process, and far more common on boats that are in the water all their life (big sailboats). For kayaks that are in the water for a day and pulled out at night this is a nonissue. The longest kayak trip I've heard of was under 65 days. (Even a trip this long should not be a problem, although personally If I was travelling that long I'd use epoxy and put in extra compartments for holding fresh water. Epoxy has the edge when constructing tanks for potable water.)

If you want to get on the water quickly and cheaply, use polyester, lauan plywood, and/or 3/16 inch pine strips. If you want a boat that will last a bit longer and will weigh a pound less, use epoxy resin and okume or high-grade marine ply and cedar.

Some glass cloth is specially treated to work well with epoxy. Others are treated to work well with polyester. Some are treated to work well with either resin. Ask your supplier for the right stuff.

Epoxy resins use a substantial quantity of hardener. Depending on the brand you may use one part of hardener to 1, 2, 3, 4 or 5 parts of resin. Packaging can be confusing if you try to compare brands. Most people forget standard measuring systems (English, or metric) and go with metering pumps. (two pumps of each, etc) With polyester you use a catalyst. The catalyst is concentrated, and nasty stuff. You want to be a bit more careful when mixing small batches as you may be measuring drops (was that a big drop or a small one?) In either case you want to mix the stuff well.

After polyester has set, it will stay tacky for a very long time if it is in contact with air. As a result, it is great for adding additional coats (no sanding needed between coats, and it sets up tacky, but hard enough to recoat in a couple of hours) The last coat however needs some special treatment to exclude the air, so that the resin can harden completely. The usual idea is to put on a coat of resin that has some styrene plastic and parafin wax dissolved in it. The wax floats to the surface, forming a thin, airtight barrier under which the resin can harden.

Because this method is so common, stores will sell two types of polyester resin. One is called a laminating resin, and it contains no wax. I forget the exact name of the other type of resin. I call it a surfacing or finishing resin, but I'm sure that is not the proper term. If you have the second type of resin (the one with the wax in it) then working with polyester becomes a bit trickier. You can put on multiple coats if you put them on while the resin is still tacky. However, if it hardens you have to get rid of the surface wax layer before putting on a second coat. So, either you work fast, and do three coats of resin on your boat in one day, or you work slow, and wait a few days between coats, and do some sanding.

There are alternate ways to exclude air from the final layer. One is to put the entire project in a bag and suck all the air our with a vaccuum pump. (effective, and used in industry, but not cheap). Or, you can wrap the project in Saran Wrap (similar effect, no pump needed. Vaccuum method is superior as it serves to force resin evenly over the cloth, eliminates airbubbles from outgassing, etc). Another way is to spray on a layer of material that will block the air. A commonly used material is the mold release goop that is used when creating fiberglass products from molds. Once the resin hardens you wash off the mold release goop with water and then sand the plastic smooth. Then you can put on a finish coat. Fibreglast says that polyester is resistant to UV, so multiple coats of varnish should not be needed. Check their website at www.fibreglast.com for a catalog, FAQ, etc. They have books and video tapes which will provide much more information, more accurately, and in greater detail than my comments. Trust them more than me ! ! !

I hope this gives you a base of information that you can add to. Best of luck with your building.

Paul Jacobson