Hello there,

Did you degas your resin? If not, that will very likely cause the problems.

Hmm. No I didn't degas. The resin I used was quite runny and I didn't stir it vigorously. I didn't see any bubbles but I guess there could have been some I didn't notice. I guess I could degas in my resin trap before infusing next time.

With a long pot life what you can do is leave the resin to stand for 10 minutes before infusing as most the big bubbles will come out then.  Also when the resin gets to the vacuum feed, allow a bit more resin to flow into the catch pot.  Once you clamp off the vacuum feed, allow the resin feed to stay open another 10 seconds or so.  The extra resin often helps avoid pin holes.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

In my opinion a really perfect finish could only be achieved with a properly degassed resin. During the infusion the resin in your part is under lower pressure, wich means the gas bubbles become bigger. Some of these bubbles than fuse, creating bigger bubbles, wich can be seen even after being brought back to normal pressure. Most of the bubbles leave the resin during the infusion, because of the lower viscosity of gas compared to resin. If you look closely, you might see very small bubbles running to the resin front during the infusion, while getting bigger. This extension is caused by the pressure difference. At the resin feed there ist allmost normal pressure, at the vacuum line there is allmost full vacuum. A properlyrics degassed resin does not degas at all during the infusion.

Degassing is totally unnecessary for a perfect cosmetic finish, I do it day in day out and never degass unless I'm doing a structural part. Degassing just complicates things unnecessarily. 

I can definitely say that degassing could be a very important part of the infusion process. Maybe it might work for some people without degassing. Possible factors might be the resin, the mixing techniques, the shape of the final part, etc. At first, infusion worked quite well without degassing. There where some pinholes most times, but far less than in my wet laid parts. But as the parts became bigger and more complicated, the pinholes got more, so I tried degassing. Since then there never was a pinhole again.
You said, that the needle didn't move during cure. This implicates that you part was under full vacuum during cure. Without degassing I would recommend not to do that. The smallest bubbles become 1000 times bigger under full vacuum. If you don't want to degas, clamp of the vacuum line first, and let some additional resin soak in. Than clamp of the resin line. This should help a lot reducing pinholes.

I guess degassing may depend on the resin and how you stir it up- if you trap a lot of air.   

I don't degas and have not had pinholes, but the resin I doesn't give me enough open time to degas.  I wonder if the extremely slow cure time played a part in creating the voids.  Anyway, it won't hurt to degas it next time.

What is your mold made of?  Is it possible that some pinholes in the mold surface allowed air to be drawn up from it?

Thanks for all the feedback.

If you're mould was porous, you'd definitely see evidence of air ingress during the infusion

As Hanaldo said, degassing is largely unnecessary to achieve perfect cosmetics. I too do infusions nearly every day and no longer bother using my degassing chamber as there has been no noticeable difference to parts even when starting the infusion very soon after mixing.

A lot of the trapped air will evacuate during the infusion process anyway and ensuring that enough resin has flowed to wet-out the stack is key to ensuring a perfect surface finish. Using resin breaks and making sure that every bit of your part has fully wet-out (even any excess peel ply near the exit) should ensure that your part comes out without voids, as appears to be the issue you've highlighted. Slowing things down is also helpful when using small-ish moulds