Hi guys,
I am trying to prepare composite laminates with resin infusion process. I am using the resin IN2 coupled with slow hardener. Unfortunately, I got many bubblea in two laminates and I do not understand why. I degas the resin+hardener compound before infusion. Here a quick description of the procedure I follow (that is the same of the video you posted on YouTube. 
1) the resin flows through the fibers 
2) I lock the inlet pipe (resin side)
3) I close the pipe outlet (catch pot side) after few minutes. 
I am almost sure that I have no air losses in my bag because I did different verifications. The bubbles appears between point 2 and 3. Do I wait too much between point 2 and 3?  Could be the air trapped in the pipe between the clamp and the resin at the beginning of the process? 
I am attaching some figure of the laminates at the end of the process. Thank you in advance and congratulations for this important forum.

Raffaele

Do you have a video of the infusion? 

Jason

"3) I close the pipe outlet (catch pot side) after few minutes."
It should be few seconds!
If the mixed resin is degassed properly and the vacuum is perfect and drop tested no way there are so many bubbles in your bag...

I’d consider a resin brake next time. From the resin line to the back edge use flow media, then from the back edge of the laminate to the vacuum line have a solid 3 fo 4 inch peel ply only layer. This will slow the resin down, allow residual gas to come to the surface and escape, and prevent resin from making it to your vacuum line before all your fibers are infused.

Jason

You might not believe me but to me, by seeing your pictures after infusion I'm pretty sure you have a leak somewhere. those "cracks" you are seeing in your infusion mesh is 99% of the time the sign you have a small leak somewhere. 
Another possibility is you dont have enough resin in your laminate during the infusion and close the lines, the resin in the laminate will look for an "average of saturation" through the entire laminate using the resin in the infusionmesh as a last resort, causing those marks you see.

If you say you are sure you dont have leaks, did you do an overnight droptest to be sure?

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

Yes, that's far too much air to be caused by degassing, at least if you degassed the mixed system. There has to be a leak somewhere.

Dear guys,
Thank you for your help. Yesterday, I repeated the infusion by using your precious comments. I can say that the biggest problem was mainly due to the fact that I closed the outlet clamp in late (in the case of my first infusion).
As you can see by the pictures I am uploading, at the end of the infusion, I have no air bubbles. Unfortunately the day after I found some thin air bubbles on the top surface of my laminate. 
In your opinion, can this problem be due to the degassing phase? I kept the resin (IN2 with slow hardener) under vacuum for 15 minutes. there were just few bubbles that were coming out at that point. 

I hope you can help me again.