I hate to ask for this. I know its been discussed many times, but can someone give me some links to sites with fiberglassing tips/instructions. I've seen them on RCO, but I need to start before Christmas of 2010. (thats how long it would take to pull up RCO). I started glassing the vertical fin on my Mirage. I have used .75oz. cloth and epoxy finishing resin to do the first coat, but don't remember what grade paper to sand with, etc.

Thanks,

Mark

>>>
I have used .75oz. cloth and epoxy finishing resin to do the first coat, but don't remember what grade paper to sand with, etc.
<<<

Individual preferences vary but after that first coat of resin I sand carefully with 120 grit then do the prime and sand routine.

Mike

Mark,

This should answer all your glassing questions!
http://www.arts-hobby.com/fiberglassing01.html

Todd

Thanks Todd, That is the link I remember reading. I just lost in somewhere along the way.

i have only west systems epoxy would that work in place of the z poxy?

The West systems is what I have switched to recently, it does not seem to shrink as much. BTW I would not sand anything but the edges of the cloth after the first coat. You don't want to cut through the cloth if you can help it so I always put on a second coat of resin prior to sanding.

David Reid

Dave: After you put on the second coat of resin you sand? Then prime, sand, prime, paint? Bkf

You should sand between the first, and second coats of resin. The rule is never apply resin over the shiny unscuffed surface of a previous layer of resin. Otherwise delamination could occur later on due the poor adhedsion to the unsanded surface.

Rich,

Actually it really depends on how soon after the first coat of resin goes on that you apply the second coat. I still usually lightly scuff between coats but it is so easy to cut through the cloth that I don't get over enthusiastic. I have also just put the second coat on without scuffing and have never had a problem with delaminating. Now if you are using a waxed polyester resin......that's a different story.


And my routine is usually more like glass prime, sand, putty, sand, prime , putty, sand, prime, sand, putty some more, sand, prime......... then I paint!!! LOL

DavidR,

Even if you apply the second coat while the first coat is still wet - you should still sand it first. Ain't you even heard of wet sanding.

I gotta think of everything.

I never sand with more than 80 grit too......when I get to the 80 grit......I know it is time to paint! And wet sanding I thought that meant to throw wet sand on the model while the epoxy was still curing....

Thanks for all the help Rich!

DavidR,

You mean I been doing wrong for all these years. Now I gotta go out and buy a bucket of wet sand for my next project so I can do it right.

...so i need sand....

just joking
but now seriously whats the step by step?
is there just a web page?

i guess i need en eye exam
i seem to be blind

I have dirt under my nails, and I'm not sure what(though it is pretty gritty) between my toes. Will this be suitable substitute for sand?'
Seriously, though...I split the difference between David and Rich. Either sand every single spot before applying the second coat of resin, or sand nothing at all. I think either one works. What I have found is that if there is not a consistent texture to the first layer of zpoxy and cloth, that there will be pits with not enough resin in them on the second layer. Not sure WHY it happens, but it frustrates me to hell.

I have a pretty complete section, with a lot of photos and CAD images on my web site. It's more concerned with plug and mold making than fiberglassing a finished wood structure, but you might want to check it out. (This is a personal, non-commercial site... all free) Hope this helps.

Go to htp://www.nextcraft.com/rcindex.html and click the "Design and Building Tips" link

OK I am just sitting here looking at the center section to a Bobcat. I just put the second coat of epoxy on it. The first coat was thinned West systems. I just finished painting a Bobcat that I glassed using Z-poxy and thought I would NEVER get the wood grain filled. This is one that we flew at Superman in primer so it would have PLENTY of time to shrink up.

Like Easytiger mentioned I have done it both ways. I have never had an epoxied surface dealminate. I have tried glassing dozens of different ways and they all seem to work. The only time I ever had problems with delaminating is when I glassed with some waxed polyester and I played hell with that. We placed the plane out in the sun after applying a coat of white primer after the final K-36 primer. The glass blistered up in little 1/8" to 1/4" blisters in small areas on the top and bottom of the wings. The Polyester has its advantages, low shrinkage, but this problem with the delamintaing made it NOT worthwhile.

Art's techniques seems to work well.....although I am not really patient enough to wait 5-7 days before sanding.

Guys &Gals,
I have used West Systems Epoxy and I use another Technique to get the job done faster.

I go to my local fabric store and purchase some polyester fabric. It looks like a silk scarf. Really fine weave to the cloth.

I apply the fiberglass cloth and squeegee the West System epoxy on using a "credit" card sized piece of flexible plastic. Starting from the center of the part and working out to the edges.

Here is the trick part: I then lay the polyester cloth over the WET epoxy and smooth it down with my squeegee. Be sure the polyester is overhanging the fiberglass/epoxy by at least one inch or so.

Let cure over night and carefully separate and peel the polyester cloth off of the fiberglass.

This will leave a surface with a "Million" tiny "Nails" of epoxy sticking straight up from the surface of your part. Use 220 grit Wet or Dry sandpaper and lightly scuff the "Nails " down.

In about 5 minites you are ready to prime.

If you want to vacuum bag you can add a layer of 1/8" felt and do both sides at the same time.

The excess epoxy goes through the polyester cloth and since the polyester cloth will not stick to the epoxy it will peel off. Taking the excess epoxy with it

Try it, it works!

Terry Holston

Fellow modelers,

There are many ways to apply fiberglass to your balsa sheeted structures.

My website (www.arts-hobby.com) describes one of those ways. However, it is not the only way.

I added the step-by-step instructions for modelers who had never done fiberglassing and couldn't find a local expert to learn from. The method I describe works very well and provides a near perfect, long lasting, contest compatible finish. However, it's not the only way to do it . . .

For example, since creating the website instructions using Z-Poxy finishing resin, I have fiberglassed using WEST Systems 105 Resin with 206 Hardener. The WEST Systems epoxy dries much harder, is stronger and provides a more dent resistant fiberglass finish.

Does that mean Z-Poxy doesn't work? NO. It means WEST Systems provides a finish with different characteristics, that's all. Some of those characteristics I find beneicial. Other users may not.

Bottom line is this: you need to use the technique and materials that work best for you. If you have never done fiberglassing before, the instructions on the Art's Hobby website provides you with a process that works.

One more thing, on the 3+ day cure times I recommend . . . I have found the longer I allow the Z-Poxy to cure, the easier it is to sand without balling up or loading the sand paper. I've found that 5 days works great for me (and others who have used it in similar circumstances and weather conditions). If you get satisfactory results using less cure time - Great! Go for it.

Best regards,
Art Gajewski
Art's Hobby, L.L.C.

Hey...Hey, I like it. A cheap and convenient source for peel-ply.

Thats right, where do you think I got the idea? I'm just naturaly cheeeeaaap! Uh, I mean Frugal!

Terry Holston

To Terry: what is the purpose of the polyester layer when you do not vacuum bag? Thanks.

Woketman, the layer of polyester removes the layer of Amine Bloom (Sp) that is present on all cured resin. That is the stuff that cloggs your sand paper.

It also removes the excess resin that will soak through when you squeegee it down.

AND those little "Nails" I mentioned before are much easyer an quicker to sand off than all those holes are to fill!!!

Hope that helps,