So before anyone jumps down my throat about the advantages of epoxy vs polyester...I know that everyone on here recommends epoxy and love it...etc...etc. However, I have to go with what is readily available to me and stay within my price range.I could order epoxy but I am really considering the polyester. First, I would like to understand the layup process using poly. My understanding is that you can thin the poly out with acetone and it will allow it to soak into the wood,thus increasing its bond strength and strengthen the wood. One question I have is do you allow this to dry/cure out first or do you immediately start laying up the glass? Secondly, do you apply a second coat of poly over the glass once it's cured or can you go straight to paint? The reason I ask all this is because my boat will not stay docked somewhere, it will probably at most see water once a week, and will not be in the water longer than 4-5 hours at a time...and that's pushing it...also it will most definitely be kept indoors when not in the water...this is a fishing boat for personal use not a leisure/house boat or anything of the sort. I doubt very seriously that it will even see water once a week in the summer...it is more likely to see water once every other week. I would really like to learn some more about the layup process using poly before I make a final decision of poly vs epoxy. I know that epoxy bonds to pretty much anything you apply it to but if I can use poly with proper surface prep than I will. I look forward to serious comments and discussion on this so I can make the right decision.
Polyester resin...epoxy resin?
- Thread starter Chulke
- Start date
I guess I'm an epoxy "purist" because of its superior bond strength and forgiveness to error. Even with superb poly surface prep, epoxy will bond and seal better than poly. Thinning the resin won't get you as deep of penetration than if you heat the wood (leave it in the sun for a while before applying resin).
Poly does its best bonding when it's laid up all at once with gel coat. It's still widely used in molding applications. But it does absorb water after a while.
I believe Ron has used poly to build stitch and glue boats so hopefully he'll jump in and provide some thoughts.
I can appreciate building on a budget. But I'd hate to hear you had to scrap a few panels and start over because the catalyst didn't kick right. Good luck!
Poly does its best bonding when it's laid up all at once with gel coat. It's still widely used in molding applications. But it does absorb water after a while.
I believe Ron has used poly to build stitch and glue boats so hopefully he'll jump in and provide some thoughts.
I can appreciate building on a budget. But I'd hate to hear you had to scrap a few panels and start over because the catalyst didn't kick right. Good luck!
I have built several boats with poly, and you can do it
BUT
the reasons to use poly just arent there anymore.
My main reason was price now there isnt much difference ,you can order a three gallon kit from US composites of epoxy for about the same price as three gallons of poly. Less toxic, working time is much better ( with poly you have to fly)it is much easier to get a good finish with a tenth the sanding . I want use poly again.
Ron
BUT
the reasons to use poly just arent there anymore.
My main reason was price now there isnt much difference ,you can order a three gallon kit from US composites of epoxy for about the same price as three gallons of poly. Less toxic, working time is much better ( with poly you have to fly)it is much easier to get a good finish with a tenth the sanding . I want use poly again.
Ron
One more thing
it takes a third less epoxy than poly so I am not so sure if the epoxy isnt cheaper
Ron
it takes a third less epoxy than poly so I am not so sure if the epoxy isnt cheaper
Ron
So how much would you estimate for a 16' Jon boat with a 46" bottom and 18" sides...I plan on glassing the whole bottom, inside and out as well as the seams. I'm going to tape the seams and then lay the glass on the bottom which will lap over the seams and part way up the sides. My glass for the bottom is 60" wide. My current guess is about 3 gallons. 
I can build 2 yaks from 3 gallons so that should be plenty,
taping then glassing to me is not the way to go , run your filets then glass,you might add tape in high wear areas.
Maybe Matt will chime in on this
Ron
taping then glassing to me is not the way to go , run your filets then glass,you might add tape in high wear areas.
Maybe Matt will chime in on this
Ron
The way I do it is glass the hull then install runners and glass over them. They take the most ware so if the ware through you still havent lost the integrity of the hull.
Ron
Ron