View Full Version : Best place to purchase polyester resin?

11-17-2003, 01:02 AM
As a first tack and tape project I'm building Bolger's "Nymph". I don't need that much polyester resin but was wondering what is the best place or type of place to purchase the resin, hardener cloth, brushes etc. economically?

Todd Bradshaw
11-17-2003, 01:26 AM
If you value your time, money spent and the hopes of many years of enjoyment with your boat, you'll purchase epoxy resin, rather than polyester. It bonds much better and is available from companies like Gougeon Brothers and System Three. There are polyesters which stick pretty well to wood, but they're few and far between. It would be nuts to buy one without doing a lot of serious testing first and even a good one won't stick as well as epoxy. The epoxy companies are quite serious about building complete systems of resins and mix-in fillers to specifically work on wooden boats. You want to know how many polyester resin manufacturers specially formulate their resins to work well on wood? None of them!

11-17-2003, 09:39 AM
The material list I got with the plans said polyester so I am glad I asked. Is west Marine a good economical source for epoxy resin?

John of Phoenix
11-17-2003, 10:27 AM
I've use West, Raka and Glen-L. Raka is my favorite. Raka is a more forgiving 2:1 mix vs 5:1 for the others and seems to blush less also. They have everything you need; epoxy, pumps, fabric, application tools. Good prices and excellent service.


Keith Wilson
11-17-2003, 11:10 AM
Well, I built a Bolger Gypsy out of Payson's book as my first boat. I didn't know any better, so I used ACX fir ply and Polyester resin. Fourteen years later, the boat is still doing fine, despite indifferent care and being stored outdoors. The daggerboard rotted, the Weldwood glue in the mast gave out, but the polyester resin in the hull is still just fine, thank you. If you use nice clean new fir plywood and work with reasonable care, you can build a perfectly good small boat with polyester resin, although it will be better with epoxy. Epoxy is also less toxic and smells a whole lot better. OTOH, it costs at least three times as much. West Marine is fine for polyester. I use System Three epoxy, which I buy directly from them

If youíre going to use epoxy I recommend System 3ís ďEpoxy BookĒ as by far the best basic reference about how to use the stuff, whichever brand you buy. You con download it from the System Three website (http://www.systemthree.com/index_2.asp) (you have to register to get to that section), or you can get a copy with their trial kit.

If you use Polyester, be aware of the difference between lay-up and finishing resin, which is NOT explained in Paysonís otherwise excellent book. Polyester resin doesnít cure completely if exposed to air, so with plain (lay-up) resin thereís always a thin sticky uncured layer on the surface. This is very good for bonding to the next layer of resin, but nasty to sand (donít ask me how I know this :rolleyes: ). Finishing resin has wax added. The wax floats to the surface, keeps out the air, and allows the resin to cure completely. The wax then has to be removed before painting or putting on another layer of resin.

Bolger has two versions of the Nymph, narrow and wide. The wide one is called the Rubens Nymph; itís identical except that the transoms and bottom panel are a foot wider. IMHO, itís a more useful boat, although it looks a little chunky. The original Nymph is a bit tender; the wider one you can just about dance in and not get wet. I donít think speed is much different; no 7í-9Ē boat is going to be fast. I thought about splitting the difference and making it only 6Ē wider, but ended up building the full-width Rubens version.

If I were going to build another one Iíd do one major thing differently; Iíd get a sheet of 3/4" ply for the transoms and frames. Itís hard to fasten the thing together for taping if you canít screw directly into the edges of the frames, and 3/4 plywood makes it a lot easier. The thicker plywood also lets you cut the frames way down so that they donít get in the way nearly as much; theyíre also less vulnerable to physical damage. The edge of a 1/4" bulkhead is a pretty fragile thing. Weight increases by a few pounds, although eliminating the transom framing partially offsets it.

[ 11-17-2003, 11:12 AM: Message edited by: Keith Wilson ]

11-17-2003, 11:29 AM
Here we go again. Never... ever use polyester resin. The boat will implode when you least expect it causing serious injury and even DEATH to all on board! tongue.gif

Bruce Hooke
11-17-2003, 11:47 AM
Jimnmad -

You've stumbled into one of the great debates of the wooden boat world - Polyester vs. Epoxy resin...

Some good and durable boats have been built using polyester resin. My take is that if cost is critical for you then polyester can certainly work. HOWEVER, you are not talking about a lot of resin here, so the added cost for epoxy will not amount to much. Epoxy has what I think are some big advantages over polyester:

- Smell - I routinely use epoxy in my basement workshop and you don't even notice any smell in the basement let alone upstairs in the rest of the house. I could never use polyster resin in this space both because the smell would be absolutely horrible (if not lethal) in the workshop and because it would permiate the rest of the house and take forever to disapate. I would not use polyester resin in any space that is not VERY well ventilated or any space that has more than a minimal connections to other living spaces. For polyester, a garage with the door open is the least amount of ventilation I would consider and I prefer working outside.

- Epoxy is much more versitile - you can use it as an adhesive (glue), you can use it as a filler, you can use it as a coating, and in many other ways. With polyester you are pretty much limited to bonding parts together with layers of glass cloth.

- Mixing - Some brands are better than others, but in general I find polyester to be a real pain to mix because the amount of catalyst you need is tiny relative to the amount of resin. If you go with poly look for a package that has the catalyst in a dropper bottle and says how many drops to use for a given volume of epoxy. Brands that only use measurements larger than drops make it a pain to mix up small batches. It is also easy to get epoxies with different cure times which can help with providing time for large glue-ups or cutting down the cure time to keep the project moving.

- I know good boats have been built using wood and polyester resin, but having worked on fiberglass boats where wood parts were bonded to the hull with polyester resin and the bond let go over time, I just don't trust wood-poly bonds that much. The places where this happened were largely places where the wood was starting to deteriorate, but it seemed like it didn't take much degredation of the wood for the poly bond to fail.

My favorite epoxy book is The Gougeon Brothers of Boatbuilding, but this book may be more than you need for a simple project such as the one you have in mind.

Keith Wilson
11-17-2003, 11:57 AM
Lest I was not completely clear, the only advantage of polyester is cost. There are, of course, those amazing hallucinations you get if you breathe too much of it, but they're not to everyone's taste. Epoxy is better in every other respect. I don't use polyester any more.

[ 11-17-2003, 11:58 AM: Message edited by: Keith Wilson ]

Wayne Jeffers
11-17-2003, 11:59 AM
Fiberglass Coatings, Inc., has an inexpensive 1:1 epoxy laminating resin that I like.



Todd Bradshaw
11-17-2003, 12:23 PM
That smell that Bruce mentioned is highly explosive. If you use it in your house the explosion will probably kill you before you get high or stink-up your carpets. As Keith said, you can build a durable boat with polyester. When I first started building strippers, it was all we had and some of those boats are approaching 30 years old and still holding up pretty well. The problem is finding a specific formula that works well for what you're doing and which bonds well enough - and that's the tricky part. Many of them will peel away from the wood too easily and others may be too brittle. The polyester that we finally settled on was a production laminating resin which had been formulated for application in the type of typical working conditions found in the Northwestern U.S. (Techniglass 329-2). We were in Illinois, but it still seemed to bond better than any of the other brands we could get hold of. We used a base coat or two on the bare wood of Laquer Sanding Sealer. This soaked in much better than the resin and helped the subsequent resin layers bond to the surface (kind of like prehistoric CPES). The final result was pretty durable and I believe even more abrasion resistant than any epoxy I have used since. You could also sand it with high-speed machines without the generated heat smearing it - something that you can't do with many epoxies.

At that time, we were getting polyester for about $5 per gallon. I had been using epoxy in college a couple years earlier and even back then it was $50-$60 per gallon so the economics were a no-brainer. It's certainly possible to walk into any automotive parts place or marine supply house and buy a brand of polyester off the shelf that will work, but you won't know whether it will or not until you've finished the boat and used it for a while. At that point, it's a little late to re-think the issue. When there are now so many epoxy systems specifically formulated for the exact job you have in mind, experimenting with other resin may well be false economy and something you regret. It also pretty much kills the value of the boat, should you decide to sell it at a later date.

[ 11-17-2003, 12:27 PM: Message edited by: Todd Bradshaw ]

Todd Bradshaw
11-17-2003, 12:40 PM
I did, however, once do a two-gallon solid polyester pour in my dorm room when I was a sculpture major in college. You could smell it about half-a-block away for a while. Nobody else seemed to complain though - at least not after they woke up and got up off the floor...

Bruce Hooke
11-17-2003, 12:46 PM
Originally posted by Todd Bradshaw:
I did, however, once do a two-gallon solid polyester pour in my dorm room when I was a sculpture major in college. You could smell it about half-a-block away for a while. Nobody else seemed to complain though - at least not after they woke up and got up off the floor...:eek: :eek: :D :D

Ah yes, the life of an art major...I was one at one point and then I was married to one for a while. Engineering students can cause a lot of trouble -- much of it intentional and planned -- art students on the other hand often seem to be even better at creating havoc because they usually DON'T intend to!

John Blazy
11-17-2003, 01:25 PM
Here are a few points I've found throughout the years:
First, one disadvantage for me on PE resin is the shrinkage upon cure, then the excessive shrinkage over time that never stops, though the glass holds it anyway. Epoxy doesn't shrink much at all.
On the smell, however, I hired out my furniture parts to be cast by a couple shops that did nothing but PE resin/glasswork. You can imagine the smell. I asked the guys in the smaller shop about the long term health effects, and they said that they'd been working with this stuff since the fifties, without respirators, inside a closed shop (in winter, you gotta keep the heat in for curing) and they seemed ok to me. They were quite sharp, as the main guy I dealt with had just invented the mother of all spray guns for "spraying" a ceramic fiber-reinforced PE resin with the viscosity of peanut butter, and pressurized it to flow through a 3 grand Venus spray gun that had MEK peroxide fluid lines going in, two acetone flush lines, and the main resin/fiber mix going in through 1" DIA SS braided hi-pressure line from a pump that mounted on a trailer that looked like it was from a waterjet machine. The mixing nozzle was in an SS shroud that was under 5000 psi. The mix was 'hot' so he could spray a 'structural' coating 1/4" thick in one pass. He was hired by GE to make molds from parts grown in a tank through stereo lithography, and his apparatus made molds better than water cooled aluminum at half the cost, and less thermal expansion.
I've seen this gun and it almost gave me a woody.

The only health problem he had was when he was making a mold in which he added a blowing/foaming agent into the PE resin for making lightweight parts and was doing fine til he sat down in the shop to smoke a cigarette. He buckled over and had to go to the hospital (picture him laughing as he's telling me this story), and after trying to figure it all out, they discovered that the gas emitted from the blowing agent was harmless in the air. However, it catalyzes to a different form when heated above a certain temp. Basically, his cigarette had turned the fumes into a form of mustard gas.

These are the furniture parts he made with the ceramic-fiber resin (on right side of pic)

11-18-2003, 11:55 PM
Did polyester. Bought if from Fiberglass Coatings on their recomendations seeing that the boat was to live on a trailer and not in the water. One thing I learned was to thin the resin out with styrene - listen, carefully, here it comes, all those naysayers are cracking their fingers getting ready to reply - the stuff is nasty, especially the styrene. But it helped the resin stick to the wood.

Get me straight, next time I'll use epoxy, but then again, I am thinking about buying a bigger frozen snot boat than I can build.

Maybe the polyester resin has longer effects than I expected?