[blndweasel]

question from hotrodders member... posted here because it has useful info on wet layp composite work.

100% wet layup. No vacuum bags here. I sanded the tank down with 150 grit, sprayed it black with rustoleum rattle can paint, roughed up the surface just a little bit more, then layed down a thin layer of thin epoxy resin, let the resin set up (until it reached the latter end of its pot life) then just layed the fiber sheet on top, and the epoxy below will act like a glue. You can basically let this fiber dry for up to an hour or more, getting the epoxy "glue" underneath to set up real good. At that point, you can laminate the outer surface with more THIN epoxy resin. On my gas tank, since I had blending patterns of carbon fiber and carbon/kevlar, it took me over five or six laminates to get the surface smooth. I would recommend keeping it to one type of fiber though, and absolutely no more than three laminates on top.

The reason behind using thin epoxy resin is because of what I mentioned with the bubbles on the firewall. I used thick epoxy resin here, and when this stuff is in the pot mixed up it has the consistency of molasses. This is why bubbles get trapped in it so easily. The thin epoxy resin you have to let set up a little bit more in the pot before you apply it so it doesn't get all runny, but it allows bubbles to work their way out while its drying up.

A simple way of manipulating wet epoxy on the surface of the part is to use a clean, unused bondo scraper as sold at auto parts stores, the flexible plastic kind. You can use this like a spatula to manipulate the wet epoxy, and it shouldn't get caught on the fiber underneath.

You should get a feel for how much you can stretch a single piece of fabric before it begins to distort the pattern. I learned it through trial and error. The gas tank and body panels I did are relatively simple patterns, topologically. The firewall in my vette was much more complicated. I used four pieces of fabric to do this, namely, I split the entire project in half (bisected it) down the middle, and on both the left and right sides I first layed up a piece on the top half, making sure to cover the convolutions and indentations in the firewall upper half. Then I used a second piece on both the left and right sides to cover the large flat areas, making sure to keep the pattern clean because this is the most noticable aesthetic part of the firewall. Then, after cleaning up the ragged edges (some of this was done before the bottom pieces of fabric were layed up), using a dremel tool and sanding drums, also a structured tungsten carbide cutting bit (these things are worth the $15, they cut through dried carbon fiber like a hot knife through butter), I cut out excess material and did the final lamination.

In my case, I used thick epoxy resin on the firewall because I wanted as little seepage and running as possible. I think in hindsight this was a mistake, because when I went to polish this surface, tiny air bubbles existed right below the surface. Thin epoxy resin is harder to work with, produces thinner layers of laminate, but overall retains a more appealing look when it's said and done.

Good luck and let me know if you have any more questions.

Other info... Only sand between laminate layers if you've waited more than 2 hours since the last layer, or if you notice "clouding" in the resin (a result of moisture condensing on the surface of the drying epoxy)

Polish with increasing fineties of sandpaper, all the way up to 1500 or even 2000 grit, then polish with 3M rubbing compound, and finish with 3M finishing compound.

Apply UV sealant if you wish, but I prefer the raw epoxy surface. If you scratch it or leave a mark, just polish it again! Besides I'm not sure how well paint / clearcoat will apply to a polished epoxy surface.

I'm going to post this to hotrodders to hopefully avoid answering the same sorts of questions multiple times...

Cheers!

The blonde weasel

[mxa055]

Hi there,
I know this is a buried thread but wanted to ask a relevant question.

If you manufacture a carbon fiber hood with bagging process using a mold from the current hood, first how are you supposed to form the bottom side of the hood since the mold only takes care of the upper side and secondly how can you attach hinges and supporting frame to the molded hood?

Also how many layers do you think are needed?

[OneMoreTime]

Originally Posted by mxa055

Hi there,
I know this is a buried thread but wanted to ask a relevant question.

If you manufacture a carbon fiber hood with bagging process using a mold from the current hood, first how are you supposed to form the bottom side of the hood since the mold only takes care of the upper side and secondly how can you attach hinges and supporting frame to the molded hood?

Also how many layers do you think are needed?

Actually it will take 2 molds..one for the hood itself and a mold for the underside structure..then the two are mated and bonded..the attachment points are reinforced and in the underside structure to provide points to attach the hinges and hood latch mechanism..

At least that is the way I would go about it..

Sam

[Apache_Boy]

patterntek.com is the website i believe... they actually dip whatever u have in CF. It looks great and I am actually wanting them to do my car.

[DanTwoLakes]

Here you go: CLICK HERE

[Apache_Boy]

Thank You for finding it Dan.

[Classicrod]

Being in florida, Ive seen the patterntek stuff up close. Awesome stuff. A little pricey but really what do you compare it to.

[Whelk]

I ran across this thread a few years ago.

http://forums.corral.net/forums/showthread.php?t=660756

The guy goes into pretty good detail on reproducing all the body panels of his Mustang in carbon fiber.