Thought I'd see if there are any glassing gurus out there in the World... and hopefully get some opinions. I have not had ANY chance to work on the car due to 'other' important issues. Suck when the car gets put on the back burner!! Anyway... I am in the process of rebuilding our RV due to water damage. I’ve gotten all the rotten wood out and am currently in the process of thinking about how I am going to build the front cap. The siding was constructed using FRP (Filon) laminated to plywood. My plan is to take the Filon material and basically glass it onto a wooden frame (see pic). I will be making some curved pieces of wood blocking that will go along the top so that when the Filon material is laid onto the wooden frame it will create the sweeping curve you normally see on the tops of RV’s. I was originally thinking of attach it using epoxy resin and fiberglass from the inside and plan to totally conceal all the wood in epoxy/fiberglass to protect it and will serve as a good water barrier. My main question is… which resin would be a better choice to use? Epoxy, polyester or vinylester? My initial thought was to use epoxy because I was not sure if the other resins will shrink at all causing the Filon to distort and not sit flat on the wood frame during the curing process. I want the Filon to sit perfectly flat on the wood frame and cave in or be sucked in which would result in being able to ‘see’ the framing from the outside (does that make sense?). On the other hand, if I could use either poly or vinyl resin, I’m thinking fiberglass mat would make for an easier application and can build up quicker. I also read that poly doesn’t really bond with wood like epoxy. Any help or suggestions would be greatly appreciated.

Thanks,
Rob

First off...I'm way far from being an expert. I'm an amature with enough experiance to be dangerous.

So are you saying you want a curve in the leading edge gap?


The usual method is to make a reverse mold, time and costly.

Option two

You could take a light bendable flex plywood, we used to call it wiggle board and then using a few ribs bend and nail it making the finished shape.

Then paint on a thin layer of epoxy, lay out some S-glass and there's a special roller to flatten the mat and work the epoxy in.
Then carefully paint on a bit more epoxy. This is tricky because the FG mat likes to slip around.
For simple curves and flat surfaces use the woven mat, compound curves the fiber mat. Try to keep compound curves to a minimum.

The only way to get a super smooth finish at this point is to bag it and put a vacuum pump on it.
On the cheap you just use plastic film, tape it with a few hoses. The tape will not stick to wet epoxy, so you have to plan and prep to do this.
You can use a old fridge compressor for the vac pump.

There's more to it, but if I can I'll help as you go.
Epoxy is weird, it flows, if you try to build up with it you come back 10 minutes later and it all flowing down like a melting wax figure.

I liked working with Epoxy better but it costs more. The medium cure give you like an hour worktime. 24 hours to cure. If you're getting the gallon bottles get the measuring pumps.
I got my stuff at http://www.uscomposites.com/
This is an example of wiggle board, it only bends one way http://www.andersonplywood.com/410/bending...forming-panels/

BTW unmixed epoxy lasts forever, so don't worry about getting too much. I've had my pumps in a few years and they still work fine.

I can't help you directly but I suggest you take a look at the teadrop trailer forum. Lots of great information on fiberglass, wood, and waterproofing. It's also a great way to blow a lot of time.

http://tnttt.com

Go to a wooden boat building forum and get educated.
The method and specific brand of epoxy will be clear.

Thanks!! I am actually leaning towards going this route and getting some bendable plywood for the curve. Then making my sure the whole surface transitions from flat to curve the way I like and then cover it with Filon using contact cement.

That's where my epoxy F/G knowledge comes from, I'm building a canoe.

You can use the Epoxy as a glue.
You also could just cover the whole roof with mat and epoxy bag the whole roof, then paint it with white gelcoat.


Just putting this out there as a cheaper covering...you could use Gaco Roof

I have Gaco Deck on two decks, which is the same stuff, it's just coloured and has some walnut shell in it. Tough stuff so far, two Canadian winters. Suppose to last 50 years.

It's how I'm going to replace the roof on a tent trailer I have, I'm just going to build it out of plywood, much like what you are doing and then paint it with the Gaco Roof.



https://www.youtube.com/watch?v=WSWFKrSh9xY

Epoxy, polyester etc is like asking if a /4 or a /6 is better when you ask boat builders.

Thanks for the tips!! I actually already bought the EPDM rubber roofing materials.

This is how I built my small two decks.


https://www.youtube.com/watch?v=hPKm3_O-LZE



https://www.youtube.com/watch?v=pTxp9iuT8tk

You beat me two it

Although I've read in several places that epoxy is the preferred resin when applying directly on wood. And when using as a glue.

I guess I'm over thinking this a bit cuz I don't want to screw it up. Materials are expensive and there's no second chances. And there are so many ways to fiberglass it's just a matter of picking one that makes sense.

There is a debate? Epoxy is way nicer to work from a safety perspective with since you don't have to worry about the styrenes/peroxides, it is much tougher, and lasts forever. Why wouldn't you use it? As far as I know the only good thing about polyester was that it cures slightly faster and is cheap.

Carbs

Polyester cures a lot faster and is cheaper and it is also more rigid. The fast curing is preferred when using production molds, also polyester is way better for thick glass mat layups, prefered for chopper gun, etc.
Needs a gelcoat

Epoxy is waterproof, fuel proof, is a waterproof glue, easy to work with, safer, clear, food grade flexible, doesn't need a gelcoat, etc.
For some things it's too flexible.

Both types have their place.

Sorry but that's rubbish tell me your experience with these products.....

Epoxy.

To answer you questions on comparative shrinkage - most polyesters will shrink between two and a half and three percent on cure, vinylesters about one to one and a half percent, and most epoxies will shrink less than 1/2%. When working with wood, epoxy is the best way to go because of bond strength, especially if the finished product is going to be a dark color.

Great!! Yes. This is very useful information!! Thanks!!

Well... the bendable plywood did not work

I ended up getting a 6" diameter sewer drain pipe and cutting a section out of it like so:

Wow,you are all in!

What type of RV, just curious

What kind of RV?

We had no choice... We tried to sell it but nobody was interested in a water damaged toy hauler, go figure. Having it fixed by someone or some establishment was out of the question. It would have cost more to do that than to buy a new one and we couldn't afford either. So, we got stuck with fixing it ourselves. And let me tell you... what a can of worms!!! The way they build these things are so crappy it should be illegal!! They are really made to fail in everyway possible!!

To answer your question... it is a 2004 Desert Fox 28KS Toy Hauler.