Poly -N- Wood -N- Glass Trick?

[pjc]

found this at a wood boat site--site is dedicated to the famous "Mini Max" 8' plywood hydro--mostly completed one once--lost interest (and was broke)--burned 'er.<br />Here's the quote:<br />"If you use polyester resin to tape the seams or glass the bottom, here's the most important tip of all: put UNcatalyzed resin on the wood first and let it soak in. About 15 minutes and you'll see what I mean. Then put on another coat and do the same thing. When no more soaks in, lay down the glass and saturate it, and then and ONLY then brush on a light final coat of catalyzed resin. This ONLY works with polyester resin; the catalysis is conducted down into the resin soaked into the wood. (Not the catalyst, the *catalysis*; the action is conducted by free radicals and is fundamentally an electrical phenomenon. It doesn't depend on movement of the catalyst itself, just the action it causes.) It will not work this way with epoxy resin. The main reason polyester fiberglass fails on wood is that people do not allow for the uptake by the wood, and they starve the layer when the resin soaks in, or it kicks off before it gets a chance to penetrate. Either way, the fiberglass just peels off. Many people will tell you that polyester doesn't work on wood, and then try to sell you epoxy at 5 times the price. If you get good penetration, however, the polyester glass combination lasts nearly forever. "<br />---------end quote----------<br /><br />any opinions if this is viable to glass new or existing stringer, transom, or whatever wood in our projy boats. whatcha think??

 

[Terry H]

Re: Poly -N- Wood -N- Glass Trick?

Never tried that approach but what I do on raw wood is to make a thinned mixture of resin and acetone...thinned to a water consitency...catalyze for the amount of resin used and brush on first...wait at least half hour befor glassing...I use scraper to remove as much excess resin as possible...getting all layers of glass and resin on in short order will give you a primary bond between layers...I don't know if using uncatalyzed resin will work or not, but I do know it will if you thin and prime as I stated...just a Thought

 

[JasonJ]

Re: Poly -N- Wood -N- Glass Trick?

I wasn't all that technical with mine, but I did mix for a slow kick, and was working in cool temps. I used a lot of resin, first brushing a heavy amount on the wood. The wood didn't waste much time drawing it in. I was able to then apply more resin and mat and cloth and all that, and it cured slow so the end result ended up with a good strong bond into the wood without leaching resin out of the mat/cloth/roving.

 

[BillP]

Re: Poly -N- Wood -N- Glass Trick?

I think that is a cool approach and the resin probably will kick somewhat with the later catalized applications. This is one method I'd have to do some "bench testing" with before committing to a real job. I really think doing a catalized thinned coat first is better. I know polyester penetrates enough to peel the wood plys apart with the thinning method.

 

[pjc]

Re: Poly -N- Wood -N- Glass Trick?

I am taking a long hard look at the poly resins for the AB Trihull project. <br />Reason is I expect to use tripple the quantity of resin than I'm using for the Slikker projy. Am exclusivly using epoxy for that one. Mainly cause of the imo complex multiple layups I've gotta do.<br />Since i've all winter I may follow BillP suggestion of bench tests w/ poly. Anyhoo--US Composits offers a real good selection of poly products at very good prices imo. <br />Laterz all--