Despite all my efforts I have not been able to get a pinhole free surface. The materials are great, and the closest I have come, but to date I have been unable to figure it out. 

This will happen if the 2k is too thick. The solvents don't have enough space to escape.

Hi

I vac bag rather than infuse my parts so I get pin holes.  I sand the surface lightly with 500 grit paper until it is uniformly dull.  I then mix up lacquer with 2 parts lacquer, 1 part hardener, 6 parts thinner.  I then brush this on working the very thin lacquer into all the pin holes.  You will find this coat dries very quickly so you can get multiple coats out of one mix.  I usually aim for 4-6 coats of this.  You will get brush marks but the brush means you can work it into the pin holes very effectively.  Once dried overnight a light sand with 1200 followed by spraying and you get nice, smooth, glossy parts.  When spraying I put a dust coat on and allow it to dry followed by a couple of fully filmed out coats.

If you spray directly I find the pin holes trap air bubbles and the finish is very fish eyed.

HTH

How bad are the pinholes? Seems sometimes actually putting a clear coat on the part can make it look even worse and take a lot more work to get a good finish.. As a few of us know all to well.. 

Here is how my parts are coming out now. I am not using Easy-preg for this and even though it is a plain weave (I have had more problems removing pinholes from plain weave than twill) it has come out well.. It has to be laid up, de-bulked, the breather stack has to be done exactly the same way every time and then bagged and cooked at exactly the same way every time too... I would say how I do it but it took me 6 months to get here and to be honest using easy-preg or Cytec's VTF261 would be easier even though it would be more expensive. BUT if the rumours are true and the VTF material is no longer going to be produced soon (some of the staff from Cytec who make VTF have left recently because they see changes they do not like happening) then we may ALL have to find a material that will give the same results as Easy-preg (VTF261) and at the moment NO company will tell you their product is as good as VTF261. 

These are out of the mould and not lacquered..




I am not saying they are 100% perfect but they are as good as many of the VTF parts I have made and have better resin clarity..

Your parts look great. Mine come out of the mould looking the same, but still have pinholes. I'd love not to fill them, I really dislike the pinholes.  I have to join two halves and finish the join line, so currently I will probably have to gloss coat anyway. 

To get clearcoat to stick properly you need an 'adhesion promoter' sometimes called a plastciser or plastic primer.  Dustcoat it on and then spray.  If your part is particularly flexible you need to add a flex additive to the lacquer.  I did this on an EF80 resin part I made and the lacquer is still good.

Most automotive refinishing suppliers will stock these.

I have also had this problem.

I do a lot of marine parts and in general it seems that the bond between the epoxy resin systems and polyurethane paints is not so good. I spoke with one of the NZ tube manufacturers about this and they simply said to use a quality brand and put it on thick.

I have also done some yacht masts with an adhesion promoter. It seems that this adhesion promoter is more like a thinner and I think is really intended for plastics like car bumpers so I am uncertain if this has worked or not.

One part on my own boat is holding up really well after two years of sun and salt. This part was epoxy coated, sanded and sprayed with a good two part clear. This leads me to wonder if the problem is more the adhesion paints to a sanded fibre and epoxy resin surface as opposed to one that is all epoxy resin as with a coated part.

But then I also hate coating parts with epoxy systems, they generally seem very sensitive, run/drain away, often fisheye as well being really hard to sand so lately I am now working more with coating epoxy parts with a polyester clear, sanding and then spraying 2 part clears.