I
just completed painting my RANS S-19 which took 2 months and this is an account
of the process.
This is the first time that I tried painting using a spray gun so I had to learn everything from the beginning but the good thing was that I did not have to unlearn any bad habits. I decided to use the Stewart Paint Systems because it was water based and I spoke with other builders who had good results. All of my comments and tips relate to this paint system.
The proper air supply is critical. My compressor used a 220 volt 40 amp 5 HP motor which supplied 15.8 cfm at 90 pounds. I bought this compressor from Harbor Freight with a 20% discount coupon for about $700. There is no way to hook two smaller compressors together and get good results. Details are everything. The air hose was hard connected directly to the compressor regulator (no quick disconnect allowed since that reduces air flow). My only quick disconnect was at the gun. I set the regulator for 80 pounds so the compressor would cycle on at 120 and off at 160. So I had a steady air supply.
I built a paint booth in one half of my garage covering the walls and ceiling with heavy grade plastic and placed a filter at one end and a fan at the other. This booth was my weakest part of the whole system but I was able to make it work. I needed to pay attention to the details of dirt and dust and here is what I did. Before painting, I cleaned everything with a clean lint free cloth (I understand there are now water based tack cloths). I used a broom type vac and then sprayed the floor with water. I dressed in a Tyvek suit (get this brand--a discount suit does not last). Secure good lighting that can be moved around if needed. Very important is a good charcoal respirator with fresh cartridges. I took about an hour to set everything up before I was ready to mix and prepare the paint.
Jigs are an important thing in painting. Every small part had to be secured so you can paint every side. The air pressure from the gun will blow unsecured parts everywhere. If you hang parts from the ceiling, then they should be anchored to the floor so they cannot move. I found the best results where when I could paint parts in the vertical position. I was afraid of runs and sags, but that turned out not to be a problem.
It
cost me $1,500 to paint my airplane plus the compressor. This broke down as
follows: the 2 part poly paint (3 gallons), primer (2 gallons), cleaner,
aluminum Etch, finishline III Spray Gun with 1.3mm tip, and freight added up to
$1,353. The rest of the cost was sand paper, scotch bright, paint filters, etc.
So how did it go? At first, it was awful. I started with the smaller parts, rudder, flaps, etc. I had runs; I had orange peel; I had pin holes in the finish paint; I had too much paint in places and not enough in others. When it is all said, it comes down to practice. The gun needed to be about 5 inches from the target. The temperature is important. The pin holes were caused by the 3rd coat still drying off so in my case, instead of the 15 minutes recommended between coat 3 and coat 4, I extended it to 18 minutes. The good folks at Stewart were wonderful. I probably called them 6 or 8 times and they always answered my questions and gave suggestions. The beauty of the water-based paint system is that, if you are not satisfied, you can take the power washer and wash it off and start over the next day after thinking through what went wrong. This washing off thing has to happen within 45 minutes. Once the poly sets up, the only way to remove it is with paint stripper. (Been there and done that--not recommended). Acetone only dulls the finish--it will not remove dried poly.
The finished product was worth all the work and effort. The Stewart Poly system leaves a high gloss wet finish and the paint is as hard as nails. I cannot ask for a better result.
