I'm going to try Sig Koverall on a new project. Could someone please tell me how to do it?

I know that the framing needs to be treated first. Sig Stick it or Nitrate Dope? Balsa Rite?

I read about tautening and non-tautening dopes. I know I want it to shrink on the initial application.

I have open framework. This is NOT a fully sheeted kit.

I want to cut the Koverall with pinking shears and make small pieces to cover the "rib stitching" on the wings.

Can you fellas tell me all you know about using these classic techniques? I've been modeling for about 9yrs and have plenty of kits under my belt. But, I've always been a plastic film guy. I've been wanting to build more "scale" models now. I'd like to detail a cockpit. I want to use fabric and paint it for my finish. My friend has stuff to paint cars. He has 3 different guns for different types of painting. I think he has a small gun that he uses for trim and a large gun that he uses for fenders and hoods. Don't know what he uses the other gun for.

My friend said that he can get a paint addative thats used on the plastic bumpers of cars. It makes the paint flexible. Do I need that?

What kind of paint do I want to use? Latex? 2-part automotive? Water colors?[sm=tongue_smile.gif]

I would really appreciate a How Too on Koverall. I know how to cover, but I have no idea how to work with this type of material. Thanks for any help.

Rcpilet--Check out the Antiques forum, the YMF thread. I posted a bunch of pictures showing the covering of my UMF in Koverall. It's probably pages 75 or later.

You don't HAVE to pretreat the frame with dope, but it's the time-honored way; Stickbuilder recommends it, but I don't usually do it. One thing you do have to do, though, is fine sand the framework anywhere the fabric will contact it. A Koverall finish is very unforgiving and will not hide any blemishes or rough spots in the wood, except maybe a minor dent, but I'd fill it anyway. The reason I don't pretreat the wood is that I want the material to slide freely over the frame when I shrink it, so it tightens evenly. I use Stix-It only where there will be a seam; on the wings I usually cover them with one piece, so the only place that gets Stix-It is the trailing edge and aileron bays, and around the wingtip. If it's a complex wing, like an elliptical shape, or something like the Stinson SR, two pieces are probably easier.

Even if you want to shrink the cover on first application, I recommend nitrate dope for the first couple of coats. It doesn't shrink much, but has better adhesion and filling properties than butyrate. You can apply butyrate (which has a higher shrink rate than nitrate) over nitrate, but not the other way around. Koverall will shrink well enough with heat that the shrinkage from dope isn't all that necessary. When I stick my cover down, I do so in such a way that It's pretty snug before I even heat it. When I finish one piece, meaning the cover is on, all edges are stuck down and trimmed, I go ahead and iron it and pull all the remaining wrinkles out and get it tight everywhere. Then I move on to another piece and do the same thing. When all parts are covered, I start with the first piece and shrink it again, because the cover has moved and equalized itself, and small wrinkles will show up. You can tell it's tighter the second time around. Then comes the first coat of dope. When it is dry, I check again for wrinkles or loose spots and use a heat gun to pull them tight, even with a coat of dope. I apply rib and seam tapes before the second coat, and apply two more coats after that The third coat can be butyrate if you want, but I get great results with nitrate alone. Butyrate comes in colors as well as clear; if you find the colors you want, you can use butyrate for your color coats. It is also fuelproof if you are using glow power. (nitrate is not fuelproof)

I put the first two coats on full strength, and may or may not thin the third coat, depending on how smooth the first coats are. If you thin it, 70-30 is plenty. I try not to brush over the same spot more than a couple of times; load the brush, and start at the leading or trailing edge and work to the other edge. feather the layer at the leading edge so it doesn't build up unevenly when you overlap it doing the other side of the wing. LIGHTLY sand with 400 grit between the second and successive coats, especially over rib and seam tapes, just enough to remove fuzz and small bumps. Once you have three or four coats, the finish is ready to prime. I am using Rustoleum Clean Metal Primer and like the way it flows. It takes 24 hours to dry between coats (you can handle it after 4-6 hours). A couple of brushed coats with sanding between each one (400 grit is fine enough) or a couple of sprayed coats, sanding the final one, will give you a nice smooth base for your color coat. Are you planning on gas or glow power? This will determine the top coat. Latex is wonderful to use, but requires a fuel resistant / fuelproof clearcoat, and opinions vary dramatically on the best one. Oil base polyurethane is very resistant, but will slightly yellow your color coat. Waterbase poly is not as resistant as oil base, but does not yellow. Thes both work great for a gas engine plane gas doesn't bother them much at all. I am a big fan of Top Flite LustreKote clear for fuelproofing, it's fairly bulletproof against glow fuel, but you have to be careful with compatability. It works well over latex, but it is an acrylic lacquer, so enamels may or may not work. Test first on a scrap. I don't think you need something to make the paint any more flexible than it is already; a bump thet would crack or otherwise damage the paint will likely need more than touch-up anyway.
I've always painted with either a brush or spray-bomb, ihave little experience with spray guns.

Now about you idea for rib tapes using pinking shears on the Koverall. You'll get so frustrated you can't stand it. The material is very sheer, and difficult to cut along its weave. You'll get fuzzing and strings everywhere, plus the tapes you might make from Koverall will disappear when you apply them and dope them once. this is what makes koverall so nice, when you overlap the seams and seal them down, they disappear.

There are several options for rib tapes. If you have some natural Solartex, you can rip the material in thin strips, the finish holds the weave together and it tears along the weave. Notice I said rip it, not cut it. The rip, when ironed down and doped over, will smooth out and mimics the pinked edge better than you can do with pinking shears (unless you are building a very large scale,[1/4 or larger] the pinking is not really visible anyway). Pinking shears would cut the zigzag much larger than scale.

Another option is pink hair setting tape from the drug store, found where the home permanent and curlers are. It comes on a roll, is 1/2 inch wide, adhesive backed, and has pinked edges; the pinks are about perfect for 1/3 scale. Dope will penetrate it (it's a paper tape), and it sands well with a couple coats on it.

Yet another is paper first aid tape. There is 1/2 inch wide, which is also pinked, and the pinks are smaller than the hair setting tape, about right for 1/4 scale. It's translucent white, very thin, and it is also penetrated by dope. It also comes in one inch and two inch widths, but those are not pinked, but do allow for wider strips if you need them. These are what I use, and am using on the WACO.

There is also a cloth first aid tape, thicker than the paper; the 1/2 inch is pinked, as well as the wider widths. I find that it works best for simulating laced panel edges like on an SE-5a. There are pinking tapes in scale sizes available from some guys like Mick Reeves and Glenn Torrance, I believe, but your drugstore is just around the corner.

That's about it as far as my experience takes me. With your modeling experience, you'll get the hang of Koverall in no time and wonder why you ever used plastic film.

Rcpilet,

Just to expand a bit on what khodges said about rib tapes. I haven't tried koverall for rib tapes, but I can imagine the plethora of 'fuzzies' that would accompany the attempt. Solartex works well for rib tapes. Try using a wheeled fabric cutter with a pinked wheel. There are several sizes of pinked wheels, so you can find a pinking size that fits.

papermache

Thanks a million khodges. I know that had to take forever to type that all out. Really appreciate it.

Okay, scrap the rib stitching. Too much work for a "stand way the heck off in the distance" scale. It's just an off the shelf kit. Not a super scale model for static display. I'm reallyu glad you told me about how the seams disappear. I'd have been all day trying to make it look right, and the seams would have been dissappearing. [sm=tongue_smile.gif]

I'll post pics when I get to that stage. It's gonna be this summer sometime.

I am one of those who only uses two fingers to type. Wore a half inch off both index fingers getting that done. My kids were in high school when I started and had graduated by the time I finished.

To expand on the techniques a bit: if you decide to use dope to stick your fabric down, you will have to coat the framework first. Apply a couple of coats to the frame everywhere the fabric will contact it and let them dry, then lay your material on the frame. Start at one end, and while holding the fabric in place, start applying dope to the fabric, working it through to the framework, The coats you placed on the frame will soften, sticking the material down. Work out the biggest wrinkles and folds as you go, until it's all stuck down and the edges are trimmed and doped down. Let it dry and then take your air gun and shrink out the remaining wrinkles. To me, this method is a bit messier than what I described earlier.

Below are some pics showing Koverall and dope finishes with rib tapes. The unfinished wing is the top wing of my UMF WACO, it has two coats of unthinned dope. The rib tapes are the paper first aid tape. The second pic is my Bristol. This has a LustreKote finish over three coats of Koverall, and the rib tapes are also the paper first aid tape. The last two are my L-4, it has five coats of dope thinned 70-30, the paint is Rustoleum with oil based polyurethane clearcoat, and the rib tapes are the pink paper hair setting tape; note the size of the pinks. This is a 1/5 scale plane. I can't really tell the difference between the extra coats of thinned dope, and the others with fewer coats of unthinned dope. Every time you brush on another coat, the previous one will soften somewhat, so don't brush any more than you have to, or it will lump up and streak.

Khodges posts are terrific! Really good stuff. The only thing I would add is, if you haven't used Koverall before, it is very strong and can shrink A LOT with a heat gun, quite enough to crush built up fins and tail-planes. Don't ask me how I know

Thank you guys so much!! [8D] I love these forums.

The kit is a Midwest Citabria that I plan to stretch a little bit to accomadate a 36cc gas engine. I might also do a 25cc Hybrid engine that would run on a gas/glow mix. What would I do then? Gas and glow fuel?

I'm collecting data to try and convert it to a Decathlon. Both the Citabria and the Decathlon were built by the Bellanca company. Also the Scout. The Scout was the first generation and also the smallest. Then came the Citabria and a mild G rating for beginners aerobatics with a semi-symetrical wing. Finally, the largest of all, the Decathlon arrived with the highest G rating of the three, and a fully symetrical wing. The cowls on some Citabrias look like the Decathlons. They have a center "chin" on the bottom of the cowl. I believe this was a standard cowl on all Decathlons, and an optional cowl on the Citabrias with the larger engines. Perhaps the oil cooler on the larger engine hung off the bottom somewhere and that "chin" scoop was on the bottom to pick up air?

My kit has the cowl with the chin on it.

The only other difference I can see are in the turtledeck and the elevator counterbalances. The Citabria has no counterbalances, but the Decathlon does. The turtledeck on the Decathlon appears to have a center "spine" that sticks up higher than all the other stringers on the turtledeck. It has an inverted triangle appearence, where the Citabria turtledeck is flat.

It's hard to find the right pic from the correct view, but it appears to me the full scale Decathoon has a bit rounded fuse on the sides, instead of just a flat slab side. I can't tell if the Citabria is any different. I just can't find the right pictures to compare the two planes. I think I will attempt to use some radius' formers and stringers on the side of the fuse to give it a little bit of a round appearence.

It would take quite a bit of work to change the appearence of this plane to "kinda" look like a Decathlon. But, I'm up to the challenge. Aerowoof told me how to stretch the fuse sides by cutting new ones and changing the location of my window panels without making the fuse any WIDER. I can't make it WIDER or the front window and cowl will not fit. I just want to make the fuse longer, add some cord to the wing and counterbalance elevators.

Oh, and cover it in one of the classic traditions of days gone by. I think it will look really nice when it's done.

Rambling. Geeked-out on my new project. [sm=red_smile.gif] Thanks for the help guys. I'll post pics here or you can read all about it in the build thread I'm planning to do. It's going to be a while though. I have one ARF project to finish up and then I will start this kit. Hopefully, I'll get it started before the end of June. (fingers crossed) [sm=71_71.gif]

Rcpilet---I once had the Dynaflite Super-D kit, and traded it unbuilt. I pulled a lot of info off various sites about it, the Scout, and Explorer. The Super-D is the only one of the three without flaps; it and the Scout both have the 180 hp engine, where the Explorer is 160. The Super-D is 22.9 ft long compared to 22.1 of the Explorer and 23 ft of the Scout. Wingspans are: Super D,32 ft, Explorer, 34.5 ft, and Scout, 36.2 ft. from what I can see, the fuselages are essentially the same, the pics i have show very little, if any differences between them. Maybe your info is better than mine. The cabins are the same width (2'6"), length (8'10"), and height (3'11") on all three. I have a lot of other size and performance specs if you are interested. That ought to be a nice build. I'd still like to do one some day.

One last caution that I don't think was mentioned. DO NOT use a heat gun to shrink the polyester coverings (Stits, Koverall or ETC). You do not have control over the temperature. You may over stretch the fabric which will either result in a crushed structure as learned by johnvb -RCU or the fabric going past shrink into slack again, from which there is no return. Use an iron with temperature control.

I use a heat gun all the time, but you DO have to be very careful. If you find a wrinkle or loose spot after you've doped the fabric, a heat gun is the only way to tighten it up ; if you try to iron it out, especially over a piece of sheeting or rib, the iron can stick to the dope and mar the finish. In either case, you want to avoid seams to prevent them from loosening.