Sanding the primer coat

Rusty, I know your very meticulous about your finishes. I also feel that in the stage your in , nice finishes can also result in heartbreak. When your start going for the maneuvers that can rekit an airplane, nice finishes is certainly the last thing on your to do list. When finsihing a plane, most builders put a minimun of 5-6 coats of butyrate clear on the plane first. Why? when thinned down to a 60/40 ratio of thinner being the 60, the dope soaks well into the balsa and strengthens the wood. The dope also seals the wood. When you do initially get into spraying the primer, your going to sand almost all of it off. This will show all the lows and highs. Thin coats are in order as they dry far quicker and make sanding without balling up on the paper much easier.

I use 320 wet to quickly level the surfaces. The problem happens if you break through down to bare wood. In your case if you have no sealer/dope under the primer this is going to happen immediately whereas the clear would give you that much more protection without the weight penalty of the heavy pigment primer.

Flaps and elevator areas are sanded with a flat block to level the surfaces. Holding them up to the light(candling) will reveal all highs and lows. After the primer, I use a silver blocking coat just misted onto the primer. If my plane looks like a piece of mill finish aluminum, I know it's ready for color. I use spot putty to fill in defects that are small and grain areas. Grain will not be filled in with paint. Even silkspanned wood will still reveal the grain in the wood. This is why silkspan works well as it provides a lightweight and strengthful means without adding tons of primer.

My advice if this primer is shot directly over bare wood is to sand initially with 240, spray again and go to 320. A lightweight coat to make it all look even and follow that with a red scuff pad prior to painting. Typically sanding in the direction of the grain but the scuff pad can be orientated in multi directions. Ken