Talk Composites - The Forum for Advanced Composites

Is this a FAIL? Surface of sheet not flat (cloth texture showing)

http://www.talkcomposites.com/Topic37520.aspx

By Barry Marsh - 7/22/2020 8:44:32 PM







Ok this is my first attempt at a resin infusion.Things seemed to go ok, no leaks and setup kept vacuum over the curing time.
The surface which should have a glossy finish seems to be flat on about 90% of the surface. The other 10% seems to be showing the weave as it is not filled in with resin. I am sorry but I do not know the name for this issue (does anybody know the name of this?).

The part seems rock solid, resin was degassed and the part seems correct on the bondable side of the p[art.

I used 375g 5HS 6k Carbon Fibre for the finished side and 300g +/- 45 Biaxial 3k Carbon Fibre for the layers in between, purchased from easy composites. I also used their IN2 Epoxy Infusion Resin,  SLOW.

The part I made is small, approx 100mm square, this is really just a test piece. I did try to pull the resin in kind of slow (sorry not very scientific) but I have a sneaking suspicion that it maybe wasn't slow enough.

I was thinking at one point maybe thats the kind of finish I should expect from the 375g 5HS 6k weave? Is it possible to get a flat surface and is this a fail?

By Barry Marsh - 7/26/2020 10:40:51 PM

MarkMK - 7/25/2020 7:07:34 AM
I think that Chris meant that you could probably skip using the infusion mesh (flow media) altogether, being that the part is so small. This would give you a very slow infusion that would allow the resin to wet-out the fabric more completely and shouldn't pose any problems if you're using a slow hardener, but it should still infuse in reasonable time on such a small panel

It seems a bit counter-intuitive, but you would likely find things work more smoothly on a slightly bigger panel, as you wouldn't need to worry so much about controlling the resin flow. Infusing small and relatively thick laminates requires more careful planning than something closer to the size of part you'll likely be looking to make in the future







Just to say thank you MarkMK for the advice. I’ll try it also without the infusion mesh to help slow it down.

Maybe testing so small wasn’t the greatest idea.

I’ll do a few more tests small and scale it up when I get it right small.

Thanks for helping out!