Hello from Spain,

I've been learning about resin infusion for the last months but still find some issues I can't fully understand.

I'll try to explain what happened to my last two infusion projects and hope I can find some answers...

One of the projects was a flat sheet compossed by 1 layer of twill CF, 1 layer of matt GlassF, 1 layer of plain kevlar, 1 layer of diolen, 1 layer of matt GlassF, 1 layer of plain kevlar.

The other one was a more complex shape but only compossed by 1 layer of twill CF, some strands of CF to increase strengh in the dessired direction, 1 layer of matt Glass fiber (only in specific points to build up some thickness) 1 final layer of diolen.

Both molds were under 'full' vacuum (-1 bar gauge reading), closed inlet and vacuum ports and left for 12 hours watching fors lacks. No lacks found, pressure kept at -1bar gauge after 12 hours.

Mixed resin (EC infusion with fast hardener), degassed the resin and after a couple of minuts started infusion.

Here starts the headache...

Once the infusion started I could see air boubles travelling across the mould and the vacuum port showed air mixing with the resin while the inlet port showed cristal clear resin flowing into the mould.

This happend in both projects.

The 'full mounting'


Inlet port

Vacuum port

Trapped air

Final results



Air showing, this are the only cosmetical results on the final product, not a real issua as it can be solved with the laquer, but this pinholes shouldn't be there in a infusion project...any idea of what may be happening?


Thanks a lot!!

It is normal to get some bubbles on the resin front and in the vacuum line.  This is the last traces of any air between the fibres coming out.  Also any tiny bubbles in the resin will expand under vacuum.

I cant see many pinholes. Slow the infusion down, or let a little more resin in to make sure the fabric is fully wetted out and/or slightly more resin rich.

Youve done well not to have loads of bridging on that complicated shape part.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Did you close the vacuum first or the resin side first?

Matthieu Libeert
Founder MAT2 Composites X Sports
website: www.mat2composites.com

Thank you Warren. My first thougth was about air trapped in the matt fiberglass, as the movement of bubbles seemed to start over the zone were this reinforcement was added and its the common point in both projects as both have some layer of matt fiberglass but not sure if this could have caused the problem.

The surface is really smooth, pinhole free except for the 3 o 4 you can see in the last photo. Not much gloss finish as the mould wasn't glossy polished. Clear coat time!

It really took me a few hours and a few meters of plastic to get some skills in the bag forming to this complex shapes. Not a pro yet but happy with my improvement.

Thanks Matthieu, maybe this was my second fail... have closed first the inlet port leting vacuum work for a few seconds more trying to fully degass the job... maybe too much vacuum in it?

I have had identical  issues when I have done the infusion in a cold environment, I know your in Spain so maybe this is not the case but issues were identical.

Another idea..

Did you leave a part of only peelplay before the suction pipe to act as a brake? Just 3-4cm are enough, It will slow down the last part of infusion and let the time for the resin to impregnate well the fabric


Alessandro

Thank you all for the answers!

Job haven't left too many time to spend in my 'test lab' but I think I found what was happening.

Andy not a Temp issue this time as we are well above 30ºC .

Alessandro, thanks for the idea, I'll do it from now on because I am doing small parts and the infusion is quite fast for most of them.

Well, I think the problem was the glass mat fibre. Replicated two more flat plates with different fibres but all of them woven fabric and then the infusion was perfectly smooth and with no air bubbles forming.

So, if I'm rigth... can't be mat fibres used into a infusion system?