Paint and polish

November 2003 – construction is all done. If I was in a hurry, I could get the thing out to the airfield now. But there’s one more thing I had to do that would make or break the finish and appearance of the plane. The paint job.

On to the computer to sketch up various ideas and pass them around to friends for comment. Finally it’s decided, deep pearl blue with contrasting pearl red, separated by white trim. The leading edges will be prepared by filling all the rivet dents to get a smooth surface and the pearl blue should look fantastic. The rest of the wing will be polished and separated by red and white trim. Cowl and wheel pants the same blue. Tail trimmed with red leading edges and a white stripe. Fuselage polished. The computer image looks great so get stuck into it.

Preparing the cowling

In order to get the shiny metallic finish I wanted on the polyester gel-coated fibreglass cowls, I spent hours filling with a West Systems microballoon:epoxy resin in a 2:1 filler mix then sanding, repeating again and again until the surface was perfect. Here you can see the filling of the rivets around the NACA ducts. I am sure you will like the white spots on the photo. The micro filler got everywhere, including the camera lens.

Ready for paint

Before applying the final colour coats, the gel-coated fibreglass cowling surface is prepared with an acrylic primer/surfacer. This is a special primer that builds up a thickness and can be rubbed back with fine wet-and-dry for a perfect finish. Any blemishes show up when the surface is wet.

One trick is to use two colours of the primer surfacer, for example white and black. Spray white over black or vice versa and wet rub back. Any low spots show up as black or white patches. Normally it is hard to see such imperfections. It isn’t as critical with an aircraft as with a car though. The primer surfacer has a high build so it should be rubbed back well or the weight can be excessive.

After primer surfacer a light final primer coat is used before the colour coats. A thing to note is that the base coat colour often needs a particular primer colour, white or grey for example. The colour of the primer underneath affects the number of colour coats needed and the final colour of the job.

The finish coats

Pearl paint is difficult to apply. It must be even or patches of different reflection come up and the colour becomes blotchy and uneven. I was beginning to wonder whether I had bitten off more that I could chew, but the expense of the paint made me learn fast. Finally a clear top coat is applied. Polyurethane gives a glossy finish but takes a long time to dry.

The wing leading edges

I wasn’t happy with the dimples caused by the flush rivets on the leading edge so decided to fill with epoxy filler. I started by dabbing straight epoxy on each rivet and heating up until bubbles came to the surface and the epoxy filled the rivet. I followed up with filler and then the wet sanding started. The same process as the cowling but much more work.

Painting the wing

The blue leading edges, white and red stripes and polished aft section meant I had to mask out every time a different colour was applied. I used greaseproof paper and ordinary masking tape for large cover but used PVC masking tape for the join between colours. This gives a nice sharp line with no bleed. This is the bottom surface – looking good.

Paint and polish

Now we’re talking. Polishing the aft section completes the planned paint scheme. The leading edge is smooth as glass. The pearl blue paint changes beautifully with lighting and viewing angle. Can’t wait to get it all together.

Big problem

I didn’t know it then, but later on when I got the gleaming blue wing out into the hot summer sun, the leading edge panels got too hot to touch. They popped and buckled like an old oil can. Back to the drawing board. I added a white panel to the top of the leading edges. Unplanned – but the effect is great. No more heat problems and a classy job. You will see more of it later.


Polishing is another story altogether. I bought the recommended Nuvite kit from Sonex but wasn’t prepared for the time it would take. Hours of buffing to get the mirror finish I wanted. I was about to give up many times but stuck at it and saw it through. Here is the front fuselage side partially polished. At this stage I only had a mind’s eye view of the total effect.

The next page in Lynn Jarvis’s Sonex project features Moving.

Lynn Jarvis’s Sonex project

  |  1. Introduction  |  2. Sonex specifications  |  3. Building the Sonex  |

  |  4. The tail and spar  |  5. The wing  |  6. The aft fuselage  |  7. More on the fuselage  |

  |  8. It all comes together  | 9. The canopy  |  10. The engine  |  11. Electrical  |  12. The cowling  |

  |  13. Paint and polish  | 14. Moving  |  15. Finishing  |  16. First flight  |  17. Natfly 2004  |