Control Line: Aerobatics
Wynn Paul
Paint Finish
The following article on paints and finishing has been in the works since last August with the tremendous cooperation of Windy Utrnowski, which included several letters back and forth for clarifications. He displayed great patience as I kept returning his letters for more and more details. Windy's modeling and stunt career go back to 1959, and his painting career goes back to 1969. He has done extensive work with all custom finishing techniques used on custom motorcycles, as well as painting guitars, custom vans, boats, etc. For the past three years, he has experimented with many two-part finishing systems with both good and bad results. His 1982 Nationals airplane, The Executioner, was the PAMPA Concours D'Elegance runner-up—even after a crash that removed the nose and the top block two weeks before the Nats! To start with, we will describe the finish on the Executioner.
Windy relates: "I started with two coats of nitrate (Randolph dope) low-shrink to seal the wood, then lightly sanded it with No. 320 sandpaper to remove 'fuzz'—but not enough to go through to bare wood. Now, using butyrate dope (Randolph dope), I covered the entire airframe with silkspan. (I used nitrate on the bare wood or Epoxolite because of its superior bonding qualities.) Another coat of clear butyrate was brushed over this. Then, after drying, I applied two coats of filler (1/3 talc, 1/3 clear, 1/3 thinner) with a trace of blue color dope to make finding low spots easier. Finally, a coat of clear butyrate sealed everything."
"Then, I applied fillets using tape to keep them even and used a Half-A prop to spread the Epoxolite to the desired shape. Next, I used an air brush to spray the fillets and surrounding areas with DuPont gray universal primer (auto primer). (I use auto primer because it shrinks very little and will stick to about anything, even contaminated surfaces.) Then, I sprayed the entire airframe with DuPont acrylic lacquer silver. SIG silver is also a good choice. However, I think that acrylics contain more solids and generally cover better."
"At this point, the plane is covered with silver paint; it is ready for 'final paint'."
Final Paint and Masking Technique
For those who have never prepared an airplane with a silver undercoat, silver shows up all the flaws—very emphatically. Usually, you will have to go back over the plane in many places to correct bad spots. Also, silver is a good base for the color coat.
Most of us at this point would now cover the entire plane with the base color coat: white if your name is McDonald, Verwaege, Fancher, Powell, Paul, or Casale; red if your name is Gieseke or Barrett; yellow or orange if your name is Whitley, Admisin, or Bob McDonald; olive drab if your name is Frank McMillan; black if your name is Glenn Meador! However, Windy has another method which is very intelligent and just plain makes good sense. Read carefully what follows.
Windy: "Now, with 1/2-in. masking tape, I masked out my trim and letters; this left me with a 1/8-in. silver outline on all trim and letters. I always paint my trim first inside the 1/8-in. tape borders and work inward with as many colors or patterns as I need. If you airbrush, this would mean one-in. tape around the outside of the silver outlines, which should be enough to catch overspray and save you the trouble of masking off the whole plane to paint the trim."
For clarification: at this point you will have a silver airplane with the color trim and letters (numbers) applied. That original 1/8-in. piece of masking tape is still on the silver, which creates the outline of the trim.
Windy continues: "When all the trim was dry, I covered it with masking tape or paper and removed all the one-in. tape outside the trim borders, leaving the original 1/8-in. tape on the silver."
More from the master: "Now, with the trim completely masked and the rest of the plane silver, I sprayed the final white coat. This method saved the weight of double paint on surfaces and the work of masking off the entire plane to spray trim and reduced the chance of tape lifting the finish in spots.
"Lastly, with all tape removed, I sanded lightly with No. 600 paper using Prep-Sol, iso-octane, or even alcohol. (This makes ink lining and press-on letter application much easier.) The next trick here was to cover any blemishes with gas-caps, 'No Steps,' inkline boxes—anything to detract from flaws. (Also, I suggest 'dark' trim only where the finish will be perfect, as dark colors show flaws more than light colors.)"
Final Clear Finish (DuPont Imron and Other Clears)
"From this point on, I used DuPont Imron," says Windy. Some of the tricks here will apply to a regular dope clear finish as well.
Windy continues: "First I airbrushed all trim edges and Letrasets to build up more material and avoid 'rub-through' areas when buffing. After 24 hours, I applied two light, wet coats of clear in a dust-free environment and let the plane sit 48 hours upside down in the 'Third Hand' (a handy item manufactured by Chuck Delano, 4631 N. Mitchner Ave., Indianapolis, IN 46226, which holds the plane by the engine mounts and allows it to be turned during painting). This made most of the dust settle on the bottom, where it will be less noticeable. I waited a month to insure a full cure, then wet-sanded the entire model to a 'flat' finish with No. 600 paper. Then the fun began with silver polish and rubbing compound to see how much I could do with a buffer. Finally, the small and delicate areas got done by hand ... think of it as jogging by hand ... we all need the exercise.
"Now, if you're like me, you'll take lots of pictures—just in case—and show it to everyone ... then fly it. The Executioner was about two months in the finishing process from bare wood to picture time."
Windy warns: "Let's discuss DuPont Imron and some hints for anyone using it. Imron mixes 3 parts clear to 1 part catalyst and then has a pot life of 4–8 hours when it can be sprayed easily. It does not get thinned. It cleans up with ordinary lacquer thinner. A critical factor is that Imron is extremely toxic. You need to wear a charcoal respirator, even if spraying it outdoors. Spraying without a charcoal respirator is extremely dangerous. Wilson and DeVillbois both make forced-air respirators for use while spraying this material, or you can use a Scott Air Pack to avoid inhaling the fumes. The tack time is very long—up to 24 hours—so a dust-free environment is essential. All resin-type finishes have a time when they start to cure and feel dry to the touch—this is the tack time. With Imron, it's usually 24 hours. There is a thinner made for Imron, but it's not necessary, because its viscosity is correct for spraying as you buy it. The Third Hand is a must, as you would be unable to spray the whole plane at once. We found this out the hard way.
"Imron will go over anything, provided the surface is scuffed with No. 600 paper first, sanding wet with Prep-Sol is first choice; sanding dry wastes too much paper and contaminates the surface. Imron will stick well even to old dope that has been cleaned (Prep-Sol or alcohol) and wet-sanded with No. 600 paper to rough up the surface. (Prep-Sol is a DuPont generic product, No. 3919S, used in auto body work to remove any silicones or finger grease just prior to applying paint.) Iso-octane is a chemical I get from Ken Purzycki. It is a super degreaser for prepping work before applying paint. When sanding with Prep-Sol, No. 600 paper is sufficient, as you only want to scuff up the old material for better adhesion.
"You can run into peeling if you apply more than three clear coats of Imron; it will come off just like Saran Wrap in a sheet! Two coats is the most I'd recommend, as the material is heavy and goes on thick. Be certain to let each coat cure for 24 hours before applying something else. A typical, 650-sq.-in.-wing ship will gain one oz. for each clear coat if sprayed with a touch-up gun by someone with a good touch. For the inexperienced, it could only add about 1/2 oz. per coat. For Wynn Paul it would be about three oz. per coat!" (Thanks, Windy.)
This discourse on painting by Windy Utrnowski (9 Union Ave., Little Ferry, NJ 07643; Tel: 201/440-0905) will continue for one or two more articles. It's great material and will be a big help to all of us.
Contacts
For information on stunt or PAMPA, contact:
- Wynn Paul, 1640 Maywick Dr., Lexington, KY 40504.
Transcribed from original scans by AI. Minor OCR errors may remain.
