What is the best way to finish a model covered in Koverall?

I have had good results with nitrate dope over the fabric, then latex paint over that. For glow fuel, you will need to over spray with urethane to fuel proof it. For gas, no over spray is needed.

Really, there are lots of possibilities for finishing. Have fun!

What kind of urethane are you using? How many coats? Does it need sanding or polishing in the end?

I have a model 75% covered with Koverall, sealed with nitrate, primed and base color applied. I am hung up there. I am uncertain on the clear finish. You say urethane. I want a nice looking finish. I have heard that water based poly works well also. Will I need to sand my trim lines?

If you paint with dope than stay with the dope. If you started with latex then stay with latex. It doesn't matter which system you use, Randolph dope, Poly Fiber (Stits Lite) or automotive paint, You get in the most trouble painting when you start switching paint systems. Since it has nitrate paint on it, paint with butyrate dope next and stay the course with dope. Dope usually reduces 50/50 with thinner, by the way.

I use the nitrate dope to adhere the Koveral to the structure and to fill the fabric weave (slightly). Also, doping Koveral makes it much better handling, as for cutting it, positioning, etc. Latex finish over nitrate dope works very well.

I have found that latex paint over dope does not hold up well. It chips off.
Jerry Nelson recommends you use a foam brush to apply his water based paint for the first two coats. That allows his paint to grab the fabric better. I think this applies to latex as well.

I have used the foam brush on my last two projects (latex over dope) with good results. The newest one is a Dynaflite Decathlon I have been flying since March of last year. The other is a 4 yr old Dynaflite Chipmunk I sold last December. Neither has had any paint chipping or any other paint issues. I am about to cover and paint a Sig 1/5 Cub and will be using this technique, as well.

In your experience with the latex paint chipping off, how was it applied? How much dope was underneath it? I am curious.

I had put on two coats of nitrate dope. The paint was applied with a foam brush.

I finished my 1/5 Sig Cub with 4 coats of nitrate dope followed by Rustoleum spray bomb (acrylic enamel), and topcoated with Minwax oil-base polyurethane. Portions of the plane (underside of wings, fuse, and tail) were done with nitrate dope followed by Top Flite LustreKote (acrylic lacquer) which also got a topcoat of oil-base poly. After 2-1/2 years, the finish is just like new, except on the underside of the boot cowl where the exhaust mist has caused the oil-base poly to wear through in a couple of places. The LustreKote underneath it is perfect.

I recently played with a piece of Koverall I attached to a frame and stretched. I painted it with latex interior house paint; the first coat was applied to penetrate the fabric, the second coat filled the rest of the weave, and the third coatsmoothed the finish to the point you could barely see the fabric. I let it dry for two days, then pulled the fabric off the frame, wadded it up, and then smooothed it out. The paint did not crack at all. I plan to cover my BUSA Bristol with Koverall and finish it this way, and then clearcoat it with LustreKote to fuelproof it.

Be aware thet oil-base polturethane is more resistant to glow fuel than water-base; oil-base will "yellow" the finish somewhat, water-base does not. I have seen on many of the models in my club that long-term exposure to fuel will break down oil-base polyurethane in areas that receive a direct exhaust spray. As an example, one of the guys has the BUSA DR-1. The landing gear winglet finish came completely off in about a year and a half with a glow engine, and the exhaust ended about 6 inches from the top of the winglet but was directed straight at it.

That's a puzzler. I also used 2 coats of nitrate dope, thinned 50/50. Also, the latex was thinned using windshield washer fluid and required several coats to cover. On the Decathlon, I also added Floetrol to the latex. The latex paint I used was semi gloss and satin finishes.[sm=confused.gif]

Try Klass Kote, it works very well right over the dope filler and lays on very well with a soft brush.

Let's see...Polyure..., Krylon, Latex house paint, windshield washer fluid, Floetrol, Rustoleum

I paint my automobiles with automotive paint. I paint my house with house paint. I think I'll paint my model aircraft with some concrete floor paint, some waterbased or waterborne house paint and OH, it has to be fuel proof. Then I'll use something at Home Depot that somebody says worked on his Super Duper Whiz Bang Flyer.

Between Jerry Nelson's paint, Sig Dope, Klass Kote, Monokote paint, Lustrekote, Randolph Dope, and Stits Lite paint for aircraft, it's going to be real interesting to see how long this thread gets on ways around using proven systems designed for Alcohol or gas powered aircraft.

Koverall is polyester. Fill the weave first, this can be with POly Brush or Nitrate dope. The idea is to try to establish a chemical bond. this can only be done two ways: chemical or mechanical. Chemical is Poly Brush, Mechanical is to saturate the fabric with Nitrate dope or whatever else you are using in this case.

Dope was used in the Olden Days to shrink the linen or cotton. It worked great because it could grab all the fibers in the threads and pull tighter and tighter. Dope shrinks through its entire life, even non-taughtening dope.

When the aircraft industry switched to Polyester ( just before jumpsuits in the 60s ) the dope didn't bond as well. Polyester is basically monofilament line woven into fabric. It's very slick with no little fibers to grab. That's why you need to Saturate the fabric. With the Stits system the chemicals all bond together beginning with the fabric and each suceeding layer.

A little known fact in the aircraft paint is the Randolph Butyrate Clear is actually half Nitrate and half Butyrate. Again, sneaking up on a chemical bond. When you apply Butyrate Colored Dope it bonds to the layer underneath, hopefully.

Chemical or Mechanical, try to get a bond so it doesn't fall off. Makes the builder look really silly at the flying field.

Anytime you're using waterbased paint you can use either foam brushes or small rollers. They work great on waterbased products but NOT with solvent based products like dope or lacquers.

Has anyone done a weight comparison on 4 coats of Nitrate, couple coats of Latex house paint, a coat or two of Polyurethane, and the other methods available?