Question for the fiberglass experts

WingsOnWheels · #1 03-28-2013, 07:13 AM

I am working on a layup where the top layer will be carbon fiber. As long as I don't screw it up I would like to show the CF by sanding and adding a clearcoat to the finished part.

Is it a good idea to still use peel-ply on top of the layup? I figured the peel ply could soak up some excess resin and leave a more even finish, but it may be a pain to sand it smooth enough to cleacoat.

Also, the part is mostly flat can I use one large piece of peel-ply, or should I stick to strips. The strips will probably leave a seam mark, but one large piece may be difficult to remove.

Maybe I'll build a composite plane one of these days. I don't know what I am doing, but having a lot of fun doing it...haha

Thanks,

g zero · #2 03-28-2013, 07:39 AM

I would use some thick clear plastic wrap , like constuction vapor barrier . Easy to see the epoxy under as you squegge the last layer .Just did this on my 8 windscreen bezel .
Tom

RV7Guy · #3 03-28-2013, 09:24 AM

If you are going to clear coat there is no need to use ply peel. Brush on your epoxy without using too much. From there you can sand from 320 down to about 600 to get the finish you want. Then go to 320 again before clear. Add lots of clear and wet sand down to 3000 if you want that glass look.

I've made several carbon parts for my plane with this process. Works great.

WingsOnWheels · #4 03-28-2013, 10:57 AM

Thanks all for the advice. I'll leave the peel-ply on the shelf!

deek · #5 03-28-2013, 06:53 PM

3 LongEZ's builder here so my advice would also be to leave the peel ply off as it tends to create waves in the layup under carbon. Also, wet layups with carbon make it tough enough to judge wetting out even without peel ply. If this isn't primary structure you will save yourself some work by keeping it "lean".

WingsOnWheels · #6 03-28-2013, 10:12 PM

Quote:

Originally Posted by deek

3 LongEZ's builder here so my advice would also be to leave the peel ply off as it tends to create waves in the layup under carbon. Also, wet layups with carbon make it tough enough to judge wetting out even without peel ply. If this isn't primary structure you will save yourself some work by keeping it "lean".

Very good advice also. This is not primary structure, so going a little light on the resin for the last layer is a good idea to improve the finish.

FresnoR · #7 03-29-2013, 09:51 AM

Make sure you use the proper epoxy. They have some mixes that are extra clear for carbon fiber use

WingsOnWheels · #8 03-29-2013, 01:00 PM

Im using polypoxy which is pretty close to water clear.

Cfrisella · #9 03-29-2013, 01:36 PM

If the shape allows this is what I've done. First make your basic part with fiberglass or carbon to your working thickness. Then sand and fill the surface like you were going to paint it. Then, apply on more layer of carbon to serve as your cosmetic layer. Only put enough resin on so the material is saturated but not puddling. Once this is cured sand it down and apply ebony colored timber mate. Then dry sand with 320 or so. Don't wash in water but acetone is fine. Then clear coat and see how looks. Your parts will look like they came out of molds.

WingsOnWheels · #10 03-30-2013, 02:50 PM

Thanks everyone for the advice. I did my layup last night and it came out great. I hope I made it strong enough, but I can always add another layer if need be.

From bottom to top, here is my layup.

Lightweight BID - 5.79oz cloth
Carbon Fiber - 5.8oz cloth
Heavyweight Double-bias nitted fabric - 17.6oz cloth
Carbon Fiber - 5.8oz cloth

Everything was done in one shot, whle the resin was still liquid. I really like that PolyEpoy since it has a very long pot life. It is really easy to work with and wets out very well without being too thin.