Re: Polyester for wood waterproofing
I don't doubt you once talked to a chemist in the field of polyester, the difference is I work with them every day and while not a chemist myself I have a great deal training and experience in that field.
If it were possible to remove all of the acetone (and you can't) then it wouldn't be quite as bad, but even when atomizing gel coat or resin through a gun there is a residual amount left in the mix. This acetone inhibits the cure by not allowing the crosslinking to be as complete as it could be. Picture a ladder with many rungs, these rungs would be the crosslinking, when acetone is added you're removing rungs from the ladder and making it weaker, the more acetone, the fewer rungs left. It's a little different with styrene, with styrene you may still get the crosslinking but it's not the same, as strong or water resistant as without it.
People always want to use the best products possible for the best results and then insist on using them in a way that compromises the product.
If you do this to the first coat that soaks into the wood, then what's in the wood is of poor quality and you're building the rest of your boat on this faulty foundation. It's the same with using the water thin resin on the cloth, you just put junk down on the cloth and then hope the rest of the laminate makes up for it.
It's like Phen-Fen, it worked very well for weight reduction and seemed like the answer to everbody's problems, plus it worked like an anti depressant. It wasn't something that was studied or recommended, doctors and others just made short term observations of people on the drug combo and on the surface it appeared to have no down side. Long term it had horrible complications like heart valve damage and related issues. Heart surgery and law suits followed.
And then back to the polyester isn't water proof comments, nothing is water proof, somethings are just more water resistant than others.
Epoxy is more water resistant the polyester, but it's not waterproof. Wood does not rot because polyester was used and a few water molecules migrated through the laminate, it rots because water got in from poor workmanship, unsealed screws, poor design, or damage, it makes no difference whether it's epoxy or polyester, the same thing happens. A typical boats lasts 20+ years before the wood rots and that's on a cheap boat, the better ones last longer. When the boat is taken apart it's usually clear as to where the water got in, and it wasn't through an intact laminate.
Epoxies are great products and there are situations where it's very important to use them, but typical boat repair isn't one of them. If these were high end go fast boats with mega HP, designed to go as fast as possible and used fibers other than glass in their construction, then epoxy is the best choice. On a normal pleasure boat with moderate HP polyester is more than tough enough. Not even the bass boat industry uses epoxy in their overpowered, light, testosterone powered rigs, it's just normal polyester. If I saw a huge number of polyester boats fall apart unrelated to wood rot, then there might be an agrument for epoxy. But even boats in which every bit of wood has turned to pulp still float and get used everyday. Just look at the number of posts with someone saying they only have a soft spot in the floor and when they take it apart they're shocked to find all the wood is rotten.
PS. I checked out Fiber Glast, it appears they give some good advice, but they don't formulate, make or blend resin (there are only a very few companies that do and I work for one), so I don't think the person you talked with was a polyester chemist.
