Patriot

I have read some info on differant kinds of fabric coverings, and would like to use a more modern synthetic fabric to cover my Citabria Pro, rather than silk which is very pricy. I have narrowed my choices down to Sig Koverall and Dave Brown Skyloft. I have heard Koverall is easier to work with, but the skyloft is much stronger. Any advice on which is prefered would be much appreciated.

I just like the fabric coverings because it looks so much more authentic and I like building then with some real craftsman skill rather than slapping them together with mono-kote. I know this sounds odd coming from a guy only 32yo, but I have been building models since I was a kid in the 70's and mono-kote didn't even exist in my small town back then, so fabric (silk) was all we had.

Anyway, you guys can weigh in on what you think is best.

Patriot1970

P.S. I have used mono-kote sveral times and it looks ok, but I have but one real opinion concerning the pathetic nature of cheap plastic film.

MONO-KOTE STINKS !!!!!!!!!!!!!!!!!!!!!

William Robison

My Feedback: (3)

Patriot:

I've never used the Skyloft, can't comment. But Koverall is quite strong enough, and it works very well.

Use it just like you did the silk, except put it on dry. Dope it down, shrink it, from there it's just like using silk.

If you want to iron it on instead of using dope, you can paint the wood with a couple coats of "Balsarite for Fabric," or "Stix-it." Then attach the fabric with heat, and proceed with doping.

Since it has to be doped anyway, I don't see the point of using the heat activated glue for the first step. But some people do.

There are other fabrics that have the adhesive on them, and even some that are said not to need any paint at all. I prefer doping it.

Bill.

vonJaerschky

My Feedback: (3)

I haven't used Skyloft either, but unless you are building a full scale 747, I wouldn't worry about the strength of Koverall! I have used it on my 1/4 Scale J-3 and my Ziroli Fokker Dr1. The J-3 thundered in very heavily a while back. The sturcture underneath was nothing but balsa shards, but the koverall harldy broke open. Go ahead and use Koverall with confidence, it's great stuff.

rc-sport

My Feedback: (12)

Before I dope the Koverall onto the frame I apply 2 coats of dope the frame sandly lighly between coats. The dope on the frame really smooths the wood and helps the dope stick. Becareful when you apply heat to shrink it, it really pulls. I snapped the trailing egde off a wing once.

Patriot

So far I am leaning towards the Sig Koverall. It seems to be the best way to go, since it can be heat shrunk as needed to get the best fit.

BeauMiller

My Feedback: (18)

Patriot,

I just finished covering my Tracer with Koverall and am pleased with the results so far (still need to paint). I did as rc_sport recommends and then applied 2 coats nitrate with light sanding and two coats nitrate/talcum to seal it. The finish is fairly smooth and added about 6 oz total for the airframe (no paint). I'm going to finish it with Sig color dope.

Good luck!
Beau

WMB

My Feedback: (1)

I've got a Koverall provect coming up also. 1st time user, what dope goes on the airframe first? Thanks, Mike

William Robison

My Feedback: (3)

wmb;

See post #6.

Bill.

linclogs

Being a "silk & dope" man for years, I started looking for something cheaper when silk started costing over $10 a yard.

I tried Dave Brown's Skyloft and it is very similiar to silk AFTER it's been applied to the airframe. It is a "continuous filament" nylon product and looks kinda like tissue paper but, unlike tissue paper, it's extrememly strong. It's a little different from silk to work with at the covering stage. You still apply 2 coats of (butyrate) clear dope to the airframe (lightly sanded bwtween coats) and you still apply it "wet" like silk. Unlike silk, Skylot EXPANDS when wet. After covering and doping down, it returns to it's original size as it drys out. That's why you must apply it wet. It won't shrink smaller that it's original size like silk does when wet.

To apply, you cut the Skyloft slightly larger than the part to be covered, then soak the piece in a pan of water for a few minutes. After a few minutes, you take the piece out of the water, let the excess water drip off, then apply it to the area being covered and smooth it out. Mist on a little water if needed until it is completely smoothed out. Then dope around the perimeter of the piece with 50/50 (butyrate) dope and thinner, rubbing it through the cloth (softens the coats of dope applied to the airframe and makes it "stick").

Once it's been properly applied to your airframe, finishing Skyloft is just like silk and dope. Fill the cloth as you would silk, apply your color coats, then spray on a final coat of clear dope to seal everything. I find Skyloft takes 1 or 2 more coats of dope than silk, but the nylon Skyloft is much stronger.

I still prefer silk, but it's gotten really expensive, especially if you buy it in small packages. I think it's over $15 (retail) a square yard now, though there are bulk sellers on the internet.

I've got some Koverall and nitrate dope to try on my next project. I'm anxious to give it a try.

frank 560

My Feedback: (6)

What do you use to spray the dope?

William Robison

My Feedback: (3)

frank 560:

For sealing the fabric a brush works fine.

Spray cans work fine, too, but in the long run it's less expensive to get a compressed air spray outfit provided you will have a lot of spraying to do.

If you'd like to try a spray gun without spending the money, many large metropolitan areas have tool rentals where you can get one for short term use.

If it's a large airplane, taking a lot of paint, the rental and bulk paint might even be as cheap as spray cans for that one job.

You would have to use a fast cure paint though, or the rental charges could get excessive.

The biggest disadvantage of compressed air spraying is overspray. There is an amount with a spray can, but it's so minimal you can use a spray can inside the house for a small job. With a compressed air sprayer you can not use it inside unless you are willing to have a paint mist on everything in the same room. And you have to use a mask. Some paints even require the use of a full respirator, as they are highly toxic.

Can't use the compressed air sprayer outside either, unless you're either way off by yourself, or are willing to endure the slings and arrows of neighbors complaining about all the tiny spots of paint on their cars.

So it comes down to a lot of capital expense, the compressor, the spray gun, a paint booth, cleaning solvents, and so forth, or using spray cans.

And if you say there's a color you want, not available in a spray can, many larger paint stores can mix the exact color you want, and put it in a rattle can, ready for use.

I used to go the compressor/gun route, but having gotten lazy mine is all spray cans now. But compressed air is useful for many things besides painting. I recommend having the compressor, it's just the spray guns I don't bother with anymore.

Bill.

rc-sport

My Feedback: (12)

Beaumiller, I've used both Sig colored dope and I've used Perfect Paint. The Perfect Paint gives a great finish but doesn't hold up well to high nitro. The colored dope will hold up to an atomic blast. I have also used Rustoleum with good results.

linclogs

I brush on the clear "filler coats", then mask and spray the color scheme. Also spray the final clear coat.

I use an old Miller hobby spray outfit. While any type of spray painting results in some overspray, the Miller system doesn't seem too bad (at least when I spray butyrate dope). I usually pull my car out of my garage and park it about 20 feet or so away. Then I mix and set up my paint and spray rig on my work bench (right next to the big overhead garage door) then step just outside the overhead door to spray. Even though the car is only about 20 - 25 feet away, I've never gotten overspray on it. But I'm only running about 40 lbs. of pressure to spray with, too. I know a lot of folks like to paint at a whole lot higher pressure and maybe that's when they start "paintin' the neighbors cars"!

buzzard bait

My experience with Skyloft was different. It drove me nuts trying to fill pin holes. Even after several coats the finish was rough. The material is one of the heaviest on the market BEFORE you put on all the dope. Once you put it on wet you cannot control the shrinkage and it warped my cap-stripped tip ribs. I think it is the same stuff they tack on the bottom of furniture. Dave Brown should be ashamed.

Koverall worked very well for me. It seals much quicker than Skyloft, it is lighter, and you control the shrinkage by how much you heat it.

For small planes (below typical .40 size) Preval spayers are a good choice. They are about $4 each at paint supply shops. Put in any paint you want. Get some disposable paper filters too and don't spray without filtering.

Rustoleum experiences vary. I used it once and it turned into a mess using 15% nitro.

Jim

Patriot

OK OK,

I think I am definitely leaning towards the koverall now, since it really to seems to be prefered by almost everyone.
I also plan to paint with some high quality auto paint from the local auto shop with high flex agents. I explained it to the guy at the auto shop and he said they got stuff so flexible now, they use it on those super flexible ABS panels, like Saturn car doors and even old vinyl roof tops etc, that flexs on a regular basis, so it should hold, and fuel proof.
I have to admit, I am a bit leary about using rustoleum. Something about paint for $3 a can at Wal-Mart. I don't know, maybe it's just me.

Patriot

William Robison

My Feedback: (3)

I've had good experience with both Rustoleum and Krylon paints.

Best to do a test panel with each, let it cure for a week or so, then see what raw fuel does to it.

A clear coat is easy if needed, and $3/can beats the pooh out of $8/can for less paint from a model supplier.

The exception is 21st Century paints from Tower. Very low priced, but not a great color selection.

Bill.

linclogs

Jim, the reason you cannot "control the shrinkage" with Skyloft is because it DOES NOT shrink. It expands when wet, then returns to it's original, dry size. So you have to keep it wet (misting) until the perimeter is down tight. Then let it dry.

You're right about the pin holes. You have to be agressive with the brush and force dope into the last few pinholes or they don't seem to go away! Skyloft is just a little bit different during the APPLICATION. But once you get that part done, finishing is just
like silk.

The roughness can be eliminated by lightly sanding (with 600 wet) after the clear coats have completely sealed the material. Just wet sand it LIGHTLY, being careful not to sand through the clear dope (especially over the ribs). If you raise the "fuzz", that presents a whole new problem. It's hard to get the fuzz to match the surrounding smooth area.

I know Skyloft SOUNDS tricky, but it's not - once you get used to the slight difference in how to work with it compared to other coverings.

By the way, I understand Koverall also suffers from that "fuzzing" problem, too.

buzzard bait

Yes, Linclogs, I understand--I refered to a helpful post of yours when I tried it, which I appreciated. But once it is glued down wet, it will shrink, and you can't control it. It pulled capstripped wing ribs in a full half inch in the middle.

Also, I was shocked when I put the stuff on a scale and found out how much it weighs. It looks light and airy, but it is actually a heavy material. And then it requires a lot of dope to seal.

When I used Koverall I estimated the weight in advance and came out on target. With Skyloft I was almost a quarter pound over estimate (.40 size plane) because of the extra dope needed to fill pin holes. I could have saved about 4 to 5 ozs using Koverall.

I haven't had a problem sanding Koverall after three coats using very fine sandpaper. With the Skyloft I had little threads all over the surface. I could dope them down, but they still looked rough. I'm glad you can get a good finish with the Skyloft on your planes, but from my own experience I would have to be holding a serious grudge against someone before I'd recommend it to him. Jim

Patriot

Ok, so after all this time, I have finally gone out and bought a quart of Sig Nitrate dope and a pack of Sig Koverall. Will be ready to cover soon.
So, here's a question for all of you Koverall experts....

What is the weight of finished Koverall? I know, I know, it depends. But figure if you use three sealing coats of dope and two or three coats of paint, what would be a good guesstimate of oz/yd? It weighs 1.25 oz/yd unfinished, so I am guessing triple that for a finished product, giving about 3.75-4.0 oz/yd. Does this seem like a good guide to go by? Or am I completed messed up here?

Any thoughts?

Patriot

CAM2

I would say this sounds about right. I use two clear coats of dope and two coats of color, and hobbypoxy clear to seal decals/panel lines on my clouddancer. I was surprized how light the aircraft turned out. I love using Koverall.

Patriot

Alright, so I took a few few general measurements of my plane, and I am looking at approximately 4500 sq in. of surface area to be covered. Thus, about 3.5 sq yd of material needed to cover the entire plane. If in fact, finished koverall comes out to about 4.0 oz/yd, then I am looking at a minimum 14 oz in weight added to the plane. So, to account for taping and extra colors for starburst design etc, my guess is I should be adding about another 6-8 oz of weight giving me a total of about 22-24 oz of additional weight to the aircraft. Does 1.5 lbs seem like too much? I am really hoping I can keep it down around 18 oz, otherwise I will be really pushing the weight limit.
So, weigh in Gentlemen!!! Does anyone else have any other weight estimations for finished Koverall?

Patriot

Oodi

I am looking at building my first Balso plane. Following this discussion I feel that Koverall is a good choice of fabric. One question I do have left is about the dope and application process. What is the difference between nitrate dope and butyrate dope?

Adi

vonJaerschky

My Feedback: (3)

Nitrate dope is not fuel proof, and must be coated with a fuel proof paint if it is being exposed to model fuels. Butyrate dope is fully fuel proof. Nitrate dope has a higher solid content, so it is ideal for attaching the Koverall and then as the base coats because it fills the weave of the fabric quicker. You can apply butyrate over nitrate, but not nitrate over butyrate. I have been using Sig Koverall and dopes for years, and have had great results with nitrate for attaching the koverall, brushing on 3-4 coats of nitrate sanding lightly with 320 grit between coats, and then applying butyrate for the colour.

Oodi

Ok, so if I understand right I can get a big jug of plain nitrate dope and thinner. This will do all the coats except for the final coat that contains the colour. How well does coloured butyrate dope cover? Do I apply the base colour to the whole model and put accent colours on top? Should I investigate an airbrush to apply the final coat(s) or is a brush fine?

vonJaerschky

My Feedback: (3)

Yes, nitrate for the base coats, butyrate for the colour. For the nitrate coats, just use a brush, no need to spray. Thin it about 25% (1 part thinner, 3 parts dope). Butyrate dope can be brushed, but it is tricky. You need to brush on wet coats, and make sure you don't go back over it until it dries. You can't just brush it back and forth. It takes a bit of practice to get the hang of. Practice on some scrap material first. Spraying is the best option. You will need to thin it 50%, and don't do it inside! Even outside, I sugest wearing a face mask to avoid breathing the fumes; it's strong stuff. How well the dope covers depends on the colours you use. The darker colours cover very well, yellows and reds not so much. If the main part of your paint sceme is white, I would paint the entire plane white and then put your trim colours over that. If you are doing something like Cub Yellow, I would first put on a coat or two of silver dope, and then the yellow overtop. The silver makes a really good base coat. It takes a few tries to get it right, I wouldn't expect perfect re****ls on your first try. But it's the only way to learn and get better! I've used many finished from Monokote, Ultracoat, Oracover, Solartex, etc, and although they all look good, I always go back to dope for my best finishes. Mind you, I've done quite a few now, and my first attempts were nothing to write home about.