Question for all you Paint - Primmer experts.

I am planning on Flying initially in WLS primmer before final paint.

My question is: When the WLS is sprayed on it is sort of rough or slightly
"dimpled" for lack of a better word, but once sanded a little is very very
smooth.

If you are going to fly in primmer should you NOT sand smooth the WLS but
leave the "dimpled" finish, or can one sand the surface smooth and FLY?

I guess the real question is: Does sanding WLS open the sealed primmer up or
cause other problems for latter on.

I hope that makes sense.

Jeff,

 

I flew my 320 in smoothly sanded WLS primer (about 320 grit) for over a year.  Final paint prep included cleaning and very lightly sanding the primer.  The resulting finish has held up (base coat, clear coat) for ten years and 700 flight hours.

 

Problems:

 

1. The WLS sanded primer coat was very susceptible to creating static in flight.  I never got the Loran receiver to work in flight although it worked fine on the ground.  Passing my hand along the cowl would cause the hair on my arm to stand up.  In other words, some avionics might not work properly whilst flying in WLS primer because of excessive static.

 

2. The temporary N-number was painted on with Krylon.  While it was easily cleaned off with acetone, it left the primer slightly raised, outlining the prior number under the final paint.  It took about 6 months before the swelling completely disappeared.

 

3. Some pin-holes were missed and appeared after the final paint.  No more than 15 gathered in about 3 spots on the side of the canopy and cowl.

 

Suggestions:

 

1. Don't sand the last coat of primer.  Leave that for the final paint prep.

 

2. If the primer is sanded, perhaps apply a final coat of primer after cleaning and before painting.

 

3. Find a better way to affix the N-number to the primer (decal?).

 

4. I only made changes to "experiments" that involved the cowl (air in and out), a wing tip and the nose gear door.  I should have painted the airplane except for the cowl before flight.  Control surfaces and doors can be easily repainted.  The cowl can always be painted later.  Unless you want to shake out a show plane before painting it or are in a rush to get it in the air, paint most of it before flight testing.

 

The problem are facts and the suggestions are worth their cost - $0.00.