If you do a corret degassing (proper chamber, full vacuum) you'll notice that even a crystal clear resin still degasses quite a lot of air. Even if you just degas your resin without stirring and without adding hardener, there will be air inside your resin. This is a physical effect, and absolutely unavoidable. Think of  the ocean: fishes ares able to get oxygen of of the water. And there is no visible air trapped.
This small amount of air is might not be the problem in a infusion, as there is a pressure gradient through your part. Only the resin at the resin front is at vacuum strong enough to pull air out of the resin. But if you clamp of the resin line to early, you'll end up with your whole part under allmost full vacuum. And as the resin does not flow anymore, the small amounts of degassed air have no where to go, but to stay in the cloth. There the small bubbles collect and form greater ones, typically at the small gaps between crossing fibres.
I am 100% sure that more resin/later clamp of will solve your problem, but will end up in a slightly heavier part.
Alternatively you could degas your resin at a higher vacuum, than the final pressure in your cavity, to ensure that there will be no degassing.

Thanks all. I have a small fiddly part to infuse this weekend. I'll use my runny slow cure resin and degas it in my resin trap after mixing to see what happens. Can't hurt but there are so many variables..

Well water at a molecular level is a product of oxygen and hydrogen, so of course there will always be air in the ocean for fish to breathe - without the oxygen you wouldn't have water. It is possible to completely degass an epoxy - assuming of course that it is a 100% solids epoxy; solvents will outgass forever - it just generally takes quite a long time and in most cases takes up far too much of the workable pot-life. It is also mostly unnecessary, as once the resin has 'foamed' and then collapsed, there is only a small amount of air left in the resin. 

The mentioned effect has nothing to do with the oxygen bound in the water molecules. Although water molecueles break up from time to time this creates (small amounts of) oh- and h3o+ ions, and no oxygen.
I am talking about physical solution. Every fluid/solid solutes molecules of the surrounding atmosphere. This depends on the substances involved, and the partial pressures. If you reduce the pressure of the system, you reduce the partial pressure of the surrounding atmosphere. As a result the substances in solution leave the liquid.
In our infusion setup, we are talking mostly about water molecules (as far as I know), which solute quite well in epoxy resin.

I used my resin trap to degas a small batch of resin in a cup. It formed a nice frothy head that subsequently clollapsed when I released the vacuum. The resin was still bubbling a bit after about five minutes of vacuum so I figure some of could be something other than air coming from the resin? A byproduct gas?

Also remember there will be some small amount of air in the fabric that comes out during the infusion process.  You always introduce a little bit through the resin feed  line initially.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant