Basic Question -Layin Up

I am completely new to fiberglassing and I would like to inquire.

I am replacing the floor in a 1955 Flying Scot 19' dinghy. After all the removal of the old floor and its balsa core - I am at a point to start placing back with new products.

I was advised by a friend to use "polyester resin" to build back the layers of balsa core and several layers of "mat" and "roving". This individual indicated that I should use "West Marine - Boater's Resin".

When reading on the product it indicates that it is the "final Coat" resin which contains "wax". I have understood that this will require sanding after each coat of resin has been applied.

Additionally -I understand that "Un-waxed" resin will not require sanding and will remain tacky.

So - my question is - which type of "resin" should I really be using?

Any advice or comments - would be greatly appreciated.

Thanks

 

Hi tradams52, the wax is called amine blush, I am using west system epoxy with 205 hardener and find if you let each coat set for about 3 hours you can add another one on top and so on without any sanding for the last coat I use 207 hardener it takes a bit longer to set but leaves very little amine blush. If your hardener is leaving a blush try giving it a wash with soapy water before you sand as the blush will just clog up your sandpaper.

 

Response to sean-nós

I have researched 'West System' epoxy to determine if it as compatible with polyester resin (the original hull was made with polyester).

At "Evercoat" they furnish lots of technical data on all their resins (on both Epoxy and Polyester) and I read where epoxy on polyester is NOT a good.

I guess what I am trying to find out is "Should I be using polyester 'laminating' resin vs. 'Final' coat resin". ??

I do appreciate your response -but I also can not afford West Systems Epoxy $98.00 gal. This is a simple area of 24" x 170". But Thanks!!

tradams52

 

Ok its simple !!
Polyester is the bottom of the barrel so just about every small boat will be made from polyester !!
Vinylester is the next step up the ladder and is a much beter quality resin and more chemically resistant etc etc . poly and vinyl wall stick pretty well to each other .
Epoxy is the odd ball !! it will stick to either of the other two But the other two dont stick to Epoxy .
If what you have is polyester then use ployester to do all your rebuild and what ever. its easyer to clean up with acetone and clean all you gear as well !!. where ever you are adding new glass , sand and clean and grind 100% clean back to raw glass before you add the new glass to do your repairs .
Theres a list of glass as long as your arm Chopped strand matt and woven roving are the normal standard every day repair and rebuild anythin types of glass you will probably be sold !!. If you need any more info on what you are doing post some pictures so it takes all the guess work out of the chatter and endless advice you could end up with . Can get a little confusing as every one has there own methods ! they all work just some are better for some things than other !!.

 

And that's only the resin; add about $40 for the hardener. I've been using 635 Thin laminating epoxy from U.S. Composites on my hull extension project. I've had difficulties using their medium hardener and have half a gallon of their fast hardener on the way. Hopefully, it'll work more like West System's 205 which I have lots of experience using. If you don't have hard, sharp corners to go around, USC's medium hardener 3:1 might work well for you.

 

Only novices buy West System 105 (and pro's looking for a special formulation). There are several discount epoxy formulators, that offer epoxy for considerably less. try Bateau.com's Marinepoxy, which is about $60 a gallon in small quantities, including the hardener. With some shopping around and buying larger quantities, you can get about $45 a gallon pricing at the retail level.

The friend that suggested you use polyester likely did so, because they know little of epoxy and it's what they're familiar with. It's easier and stronger with epoxy and you can get everything you need shipped to your door, by the big brown truck.

 

No reason to use epoxy, and no reason to use West's overpriced products. Go to any marine supply house and buy UNwaxed polyester. You don't even need "final coat" resin on the final coat. If you can spray it with water and keep it wet for a few hours (or arrange to have it rained on overnight) the deprivation of oxygen will cure the surface nicely.

 

To Tinhorn, PAR and TomHerrick -

Very good information and I thank you for your input. Your advice is very helpful in my stituation -I guess I start looking for some "thin" laminating resin and return 2 of the 3 gal of "Final Coat" resin that I purchased.

Thanks again - I'll try to get some photos up -but my back blew out on Tuesday with three bulging discs -not something I need to have happened right now.

Thanks again for your valuable input.

tradams52