Manufacturers please help

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#1

I was recently informed by my supplier that Duratec is now making a UV resistant clear gloss top coat. This is fantastic news!

Now… that one problem has been solved by Duratec… can someone create a chemical that can eliminate pinholes in cured carbon fiber parts? Pinholes are very hard to fill and most clear top coats do not like to penetrate into pinholes found in carbon fiber parts. We do many clear finish carbon fiber parts where our customer demands a perfect or near perfect surface finish - free of pinholes.

If I spray acrylic urethane over a part the pinholes do not go away… they simply pop through the clear layer also.

Can someone formulate a solution to the problem? I’m sure there will be big demand for such a product.

We can’t vacuum infuse everything.

#2

This has been discussed here before, spray the clear into the mold first

#3

When you spray the clear in the mold first do you allow it to completely dry first or just tack up prior to laying the fabric?

#4

I will give a try sometime, thanks

#5

i dont get how spraying clear in the mold first helps, wont the results similar to using a clear gel coat? wont those “pin holes” just be trapped between the first lay (clear or gel coat) and the CF?

#6

Yes, but you can’t really see them when they’re trapped between a flat layer of clear.

#7

Not necessarily.

Part of the problem with getting pinholes is in the mold release. The surface energy of the mold release is what makes it work. It also causes fisheyes when you try to paint thin resin onto the mold. It is almost like the surface is trying to throw off the resin. (Also why water beads on a released surface).

With the clear covering the mold release it allows the resin to wet it more completely. It won’t automatically solve all of your problems but it will make a huge step towards more cosmetically pleasing parts.

I hope that this is lucid. Not enough coffee yet this AM.

#8

You may also want to try calling Loehle Aviation. They have a product called Wonder-Fil. It is a paste you rub into your surface, let dry, then buff off the extra. The paste will fill in the pin holes (leaving white spots where it fills holes). You can then spray a poly’ clear over the surface. The filler will go transparent and disappear once the clearcoat wets it out. It works with a very fine fiber like compound that helps to not break the surface tension in the topcoat. Thus, no pin holes. I personally have had very good success with it on non-gelcoated parts.

#9

Before I did all the painting/clear in the mold I used to do the following:

Mix a batch of 2K Urethane, add a little bit of cab-o-sil, brush/wipe it onto the surface, IR force cure it/heat force cure it, sand it flat, then spray it. The brushing/wiping seemed to fill the pin holes when spraying would not.

#10

Spray gun in one hand, squeegee in the other…duratec or urathane