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Sonerai II Recover and Repaint
By Bill Evans, EAA 794228, Chapter 266, Montreal, QC
August 2020 – Over the years I've had aircraft painted by Aircraft Refinishing in Buttonville and others. Albe Pow did a fabulous job on my Schreder HP-11 at his shop in St. Lazare. It had ivory wings and an international orange fuselage. I'm sorry I sold that sailplane now. I'd buy it back if Robert Palfreeman would sell it. The Bakeng Duce was painted by Alain De Hondt, also at St. Lazare. Black with gold, high-gloss. We bought it largely for the paint. I learned to love to fly it, afterwards.
Painting costs increase. I heard $6,000 recently, more depending on the prep required.
When I enlarged the vertical fin on the Sonerai II, I used the catalytic paint from Continental Coatings (Ranthane). I chose the wrong paint; it stayed on and matched, but it was high-gloss and didn't suit the original Polytone semi-gloss from Ray Stitts. So the issue was gloss. My bad.
Sonerai fuselage pre-paint.
This time my friend Gord Larsen offered to help me paint at Lancaster Airparc. The hangar has a 3-horsepower DeVilbiss vertical compressor. You can run all the stuff you want. Pressure never varies far from 120 psi. But there was a caveat: Gord had used Stewart System before to paint his Jabiru 250/3300 and he wanted to use it again. He said Aluminum Metallic but I chose Silver Metallic. It does not photograph well, but in the sunlight, well it looks great to me.
Painting the new cowling.
I don't work for, sell, or advertise for Stewart Systems or anyone else. I'm a homebuilder, not a professional painter. Total cost of recovering and painting my Sonerai II LS was about $1,000.
As I see it, the advantages of Stewart are:
- Paints over aluminum, wood, steel, fiberglass, graphite epoxy, and fabric. I had primer on the cowlings, wings, and fairings. But I'd used Stewart EkoFill as the UV blocker, and since the top coat goes on in four coats, I skipped the fabric primer. Do so at your own risk.
- It has FAA approval for that (all surfaces), but in Canada you don't need approval. The builder decides what to use.
- EkoPoly is a catalytic paint so the unmixed components will last indefinitely, but the paint itself will need to be mixed thoroughly. I didn't find a drill power mixer worked any better than a stick, really! I mix a pint of paint at a time so I can cover either the whole fuselage or the wings with one batch.
- The catalyst causes the paint to set up. But the paint is propelled using distilled water; hence, waterborne. It's in a suspension, so if you stop painting, you should remix what's in the cup. The viscosity is controlled by the water. For some reason between day one and days two and three, the viscosity cup wanted more water to give 22-25 seconds. We adjusted the water a few cubic centimeters at a time. It's not hard to do. (See cleanup below.)
- The paint sets up to tacky in 30 minutes but lasts three hours in the paint cup. My cup holds about 1 cup of paint. That did one coat on one side of two wings.
When I used Consolidated Coatings catalytic paint, Ranthane, I absolutely needed a 3M full face mask with compressed, filtered air and air going into a full Tyvek suit. I had to make adapters to get compressed air to the 3M mask. I used a separate oil-less compressor for filtered breathing air. At 4 psi, when you relax compressed air fills your lungs. You exhale more or less normally. The Tyvek suit is continuously filled with compressed air. You look a bit like Michelin Man, but with that cool air supply on a very hot day, I could paint continuously for about six hours with no real breaks. When you do stop and take off the mask and suit, you are dry and cool and feel fresh. At age 73 that's worth something.
However, with the Stewart System, a face mask with suitable filters, goggles, and gloves are all you need. That is the real reason why Gord uses only Stewart.
Stewart says you must use a scale, but I did not. I used volume but corrected for viscosity with a gauge (below). In my experience on Friday and Saturday, the paint is tolerant of minute variations in catalyst. But you need the viscosity to be correct at 22-25 seconds with a Ford #4 cup. Stewart sells these, so get one. Actually, like the paint manual, the viscosity cup should come with every gallon of paint. Mixed, one gallon of paint gives you, say, six-plus quarts of paint. I also used a paint filter cone to remove any "dirt" right before it goes in the cup. A filter cone is a necessity, one per day.
They said it — one gallon covers 450 square feet. At the time of writing, I've painted fuselage, cowlings, large fairings, and both wings with four coats. Out of one gallon, I must have an imperial quart left, unmixed. I have more catalyst than I'll need. So I have choices for trim.
I tried to buy Stewart locally but they had to order my color from the factory. I called Stewart Monday at 10 a.m. EST; they mixed the paint and shipped by noon. I paid to have FedEx next-day delivery. Tuesday after lunch, FedEx dropped the paint at my door. The shipping added to my costs. The paint started around $300 U.S. By the time it was in my hand, it had cost me $800 CDN. No regrets.
I bought camlocks recently also in the USA, with a four-week delivery. It drove me mad; hence, next-day delivery for the paint. (Yesterday I ordered more camlocks and told Spruce that Stewart delivers in 30 hours. How come they take 30 days? They sent me a tracking number the next day; shipping Monday. It pays to ask for expedited service.)
You spray EkoPoly on in thin layers, so runs and orange peel are less likely. I did not use the correct pressure reducer for a gravity-fed gun, so I had one run at 120 psi but I let it dry overnight and the run all but vanished. The viscosity I used was 25 seconds with a Ford #4 viscosity gauge. The Stewart paint is called EkoPoly: paint, catalyst, and distilled water. You must have a viscosity gauge, because with the same gallon, the viscosity required an ounce more water the second day than the first. At about 25 psi with a filter and water trap near the gun, the paint is more like a fog, so it's much more tolerant of variations in thickness. It's also more tolerant of mistakes. You need a flood light to help you see exactly how the paint goes on. You also need to concentrate on the surface you are painting, not everything else going on in the hangar.
So, the four coats are:
- A dusting coat, say a 12-inch sweep per second. Wait five minutes.
- The second coat is a bit heavier but not 100 percent coverage. I sprayed coats alternating side to side and vertical. You get fewer runs with vertical. The second coat is, say, 6-inch spray travel per second. Don't go back trying to correct. Wait 30 minutes. That's why you have four coats.
- The third coat is at 90 degrees to the second. Don't forget to turn the spray nozzle to change the fan between horizontal and vertical. Again, don't play with going back.
- This coat matters. Maybe adjust your viscosity to 22 seconds, i.e., with a little less water (75 percent water). Also have someone move that flood light so it shines along the surface being painted. You operate the gun so you can see the surface into the light. Why? On the fourth coat, you want 100 percent coverage. So you adjust the movement of the gun so there are no spots or gaps in paint you are laying down. You need to look into the light's reflection to see that. If you can, apply coat four with the surface horizontal for a better flow and reduced risk of runs. I had the wings hung from the rafters so that rotation was possible. When painting wings, overlap the leading edge with each coat. My wing leading edges in fact got eight coats. Once you have that coverage, don't be tempted to go back or to use up that tiny bit of paint left in the cup. When done, STOP. Take a very good look around for small parts, spinners, inspection panels. Otherwise STOP.
If you could measure the paint thickness, you'd realize that the four coats really do lay down a substantial thickness of paint, all of them in one day.
The way this worked was the following: I needed to use the Stewart System to paint the fuselage, which is fabric so we did that first. I also did the fuselage big fairings and cowlings. That took all day Friday. Saturday saw us hang the wings from the rafters with straps, but so they could be turned. One strap was at a spar; the other around a Hoerner wingtip. You need to get the leading edges so they can be painted with each side of the wings. You want double the paint thickness on the leading edges. I used the same four-coat system for painting the wings. It went well enough. Before any of that, you wash the wings with lint-free wipes and pure isopropyl rubbing alcohol.
Fuselage painted with UV-blocking EkoFill.
The third day of painting was a Wednesday, because I found two cracks in a wheelpant and wanted to fix them first, then fill and prime. That took a few days over a weekend. Also on the painting list were all the small inspection panels and hinged access panels. There are four removable flight controls on the fuselage: the rudder, elevator, and two horizontal stabilizers. While recovering the fuselage fabric, it seemed smart to recover those control surfaces at the same time, which I did over the winter. The Stewart glue and EkoFill can be used in your garage, as they are both waterborne and do not appear to do one any harm with the garage/hangar door closed. I brushed them both on. They got painted first on Wednesday, then the fuselage panels, cover, and spinner. Finally, I got to the wheelpants. I was able to hang them from a section of 4-foot scaffolding. It worked well enough.
For cleanup, dispose of any unused but mixed paint. After the first day, I used a pint of distilled water sprayed out the nozzle for cleaning. That was enough to allow me to use the same gun on day two. After day two, I again sprayed it out with water but also scrubbed everything related to the gun with Toluol T11 paint thinner. It causes asthma attacks in some people (read: me). Use thinner outdoors and while wearing a charcoal filter mask. At the first sign of breathing issues from thinner, stop and get fresh air. At the first sign of chest pain, get help.
As I said at the start, I've used Polytone, Ranthane, and now Stewart EkoPoly. Admittedly, no aircraft paint is cheap; perhaps EkoPoly is the dearest of these three. In the world of jet aircraft, which fly many times faster than my racer, the paint such as Dulux and others doubtless cost many times the $800 CDN I paid for a gallon. Would I do this again? I think so. The paint is forgiving; cleanup is friendly. Using a viscosity cup, you get exactly the same paint in your gun each time. That paint in the cup stays liquid and sprayable for three hours anyway. Once paint and gun are set up, your only focus is painting.
Fuselage out in the sun.
The Stewart gallon is supposed to cover 450 square feet, and my Sonerai is, say, 350, but it was all disassembled so more paint was required. At the end of day three, maybe a cup of paint remained unmixed.