Hey Hanaldo,

thanks for your input. Did you already repair Moulds with a sealer? How do you do that? Sand with about 800grit and then seal?

Yep I have. Just filled the pinholes with a high temperature epoxy gelcoat, sanded flat with 1200, then sealed with the tool sealer. On a low porosity surface, you can skip the spray applications and just wipe it on.

Sound good.

I tried the xt135 this morning but I had really big issues getting the blue film off the surface ply. It seemed like it’s „baked“ together. Was this the same with yours?

I also had ambient temperature (20) and fully frosted storage... I am a bit worried that the material is bad, perhaps from the transport.

No, that's normal. The hardest thing about working with pre-preg is removing the backing film. You'll get the hang of it with a bit of practice - try using a blade to 'flick' the film away from the carbon.

I know that from the component prepreg but this time with the tooling stuff it was nearly impossible to peel it off without delaminating it. I had to cut of lots of pieces which were so damaged that you could not use it... so it was way „Harder“ than with the component prepreg. Only the bigger pieces worked pretty fine!

The tooling pre-pregs are very resin rich, so they are much tackier and harder to work with than the component pre-pregs. I remember having the same struggles, it is normal. You just have to try to get between the resin and the film, dont try to pull the film off if you havent got under the resin. 

On some pieces I did find it easier to leave them over sized initially, then cut them down a bit once the film was removed. That way I could cut off the outer bits where the resin had come away.

Happy new year!

Ok did now two Moulds and I had the same problem in both cases - lots of pinholes and it seems like there was no resin at all on some places where you only see glass scrim. But this happened not in the corners but in the flat areas!? I really do not know how this could happen. I even made 4 backing layers so that there should be plenty of resin.

So did/how did you manage the surface imperfections? Filled it up with high temp resin and flattened down? Looks like a lot of work with all the pinholes... or did you only use board sealer to seal the holes? I tried to flat one of the moulds down a bit with 1200grit to use the sealer later but I do not know if that was a good idea because now it looks like the pinholes doubled.

The tool sealer wont fill pinholes, you need to fill them with a high temp gelcoat first. It is absolutely a lot of work, wont lie to you there. 

Exposed scrim sounds like you over-handled the material, which isnt surprising given the difficulties you were having with the backing film.

The EL160 is the resin system that you would be best advised to use as the low viscosity should fill in the pinholes better. You could use the gelcoat for bigger voids. Fill the pinholes after the 65 degrees cure allow to cure at ambient and then run the post cure cycle. Only run the suggested XT135 post cure cycle. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant