2 systems required
To me overall quality of the glass was not that good. Especially enlight of the overall great quality of the metal product. The wheel pants fit together nicely but the cowl leaves a lot to be desired. Also there are waaaaay too many pinholes.
There are two types of glass disciplines used in Van's kits. (why, I don't know!!!!) The wheel pants, tail fairing and cowl are epoxy glass. The wing tips and empennage glass are vinylesther resin. Therefore there are two prep methods you must use.
As a disclaimer, this is not the only method but it works great for the initial prep and getting it filled for flying. Prep to paint ready requires much more work.
For the epoxy glass parts it is imperative that you clean them thoroughly before sanding. My personal method is to scrub with soap and water and a stiff nylon brush. Rinse and let air dry. Next I give the part a good wet wipe down with acetone and allow to air dry. Repeat the soap and water cleaning.
With a sanding block and 180 grit paper sand everything to take the gloss off. This will open up any pin holes that were not fully exposed before. Clean when done.
Study the part and look for any large voids in the epoxy. Fill with epoxy and micro filler. Depending on the size I used 5 minute epoxy and micro filler to speed the process. With practice you can fill these and not need much sanding at all. Do this for any real obvious areas of pinholes too. Use a plastic squeegee and work the epoxy in by going several directions. I also used Rage auto body filler with good results. This is easy to use and fills and sands nicely. You'll see lots of voids in the cowl where the honeycomb is laminated in.
The best fill primer I've found is the Evercoat Feather fill primer. On my cowl I sprayed the primer on the bottom half and rolled it on the top half. I wanted to see if either method had the time and advantage over the other.
In the end I found spraying worked best because the primer went on smoother and required less sanding.
After spraying the primer on the bottom I had a small cup of primer that I used to rub primer into visible pin holes. This process takes some time. Just when you think you've got'em all, more appear.
Rolling the primer on the top worked okay. This method required lots more sanding. I also "finger painted" areas the rolling didn't cover. Remember to clean thoroughly between sanding and priming.
When you think you have it, put a good coat of epoxy primer on the parts. You'll probably still see some pinholes!!!
This is good enough to get in the air. Paint prep adds many more hours and some additional techniques. It is boring and time consuming but you get out of it what you put into it!!
The wing tips and empennage glass requires slightly different techniques. I held each part to a bright light to find any voids in the gel coat. Any suspect area was punched with an awl to break open the gel coat. There are many areas that don't get noticed.
Sand with heavy grit paper to knock the shine off the gel coat. This may open some additional voids. Fill and sand. When you have everything, prime.
I should also note if you are going to attach and fill the tail glass to the parts make sure you sand the gel coat before attaching. I used epoxy and micro filler when the parts were riveted in place. Squeegee the excess with a plastic card. This way you have a good clean bonding surface on the glass. The metal areas must be scuffed as well for good adhesion.
