August 14, 2014
- Technique is everything. Painting an aircraft, or a car or even that old china cabinet, like building an aircraft, is a sequence of steps, one after the other, where each step must be completed satisfactorily before you proceed to the next one. How do I know this? By making every mistake it's possible to make and learning from them!
I had painted cars in my teens with some instruction from an older guy who was basically getting free labour in exchange for hours and hours of work. Wow, that's fortyfive years ago! Maybe that explains why I'd forgotten most of the key features of doing a good job relatively quickly. Many of you have painted your aircraft but some may be planning to do this for the first time, so this is an attempt at providing some “beginner experiences” that you might find useful.
- Perfection carries through from one coat to the next. Ditto imperfection.
- Take the time - and use very good lighting - to spot and correct every defect before proceeding. This includes feathering any filled spots before the first coat.
- Learn how to set up the gun and do a test pattern before every session. YouTube helps.
- As a first-timer, you will almost certainly get runs and sags. Don’t wait until they dry; wick them off with a fine artist’s paintbrush dipped in thinner, or lightly wipe with a lint-free cloth. It’s a lot easier to wet-sand what you’re left with, and you’ll wait forever for runs to dry.
- Position your stance so you make the full passage across the area you are painting without having to move your legs. Rehearse the pass before you start.
- If you use a respirator mask, snug it up tight immediately before you start pulling the trigger.
- Spray edges and odd surfaces first to make the final passes straight and well overlapped.
- Follow the manufacturer’s technical data sheet on flash-off time, pot life, and times between coats. Ask for these when you buy your paint or search for them online. Don’t just ask a friend. He may not know your product.
- The total time it takes to do a good job is shortest with multiple light, even coats since drying time is much longer than spraying time if you apply coats too thick. Three thin coats dry a lot faster than one thick coat. Don’t apply too much paint at one time.
- Make sure the workspace is clear of obstructions, well lit, and well ventilated.
- Use a tack rag immediately before spraying each coat to thoroughly remove any dust particles.
- Too much thinner in the paint or too much paint can make the previous coat craze. The only solution to this is stripping it off and starting again.
I used a self-etching primer on bare metal, after applying an acid based Alumiprep coating and rinsing thoroughly. I used a two part urethane for the solid white and a pearl base coat/two part clearcoat for the empennage where I wanted a red that wouldn't fade. My paint store guru told me that any red would fade unless it's under a UV blocking clearcoat.
To requote Theodore Roosevelt from Brady Lane's excellent article “Oshkosh or Bust” in the May issue of Sport Aviation, “there is no effort without error”. He also said something to the effect that you don't succeed by being in the audience but by getting “bloody in the arena” which is how I looked when the red paint I was using tried, and hopefully failed, to flood my sinuses through the sides of the respirator I was using.
I hope you get some value out of these ramblings of a rank amateur. Maybe some day we'll get an article from a real expert painter, or even a series. I spoke to one just yesterday! My conclusion, after trying this myself might be to do all the prep, and then befriend an expert! Technique is everything and there are people who have it already conquered.