JBecker

Here's a pretty good article on how to dope and silkspan a model. I don't believe too much different than dope and Koverall. I followed these instructions for covering my waco with silkspan. I had never done this before, but was very pleased with the ease of application and especially the results. Jim

http://www.ezonemag.com/articles/1996/silkspan.htm

Tommy Meisel

I've used Koverall for some years now, and it is indeed a great product. I would use silk if it weren't so expensive.

There is one aspect of working with Koverall, or any of the polyester fabrics, which no one has mentioned yet, and that is its ability to dull a razor blade very quickly. After trimming about two feet, the blade dulls and then you start getting threads pulling out of the cut edge, which are a real pain in the rear. Get a box of 100 double edged razor blades (about $6 at a discount place) and figure on using about 20-25 blades in covering a good size model. It is only a few bucks worth of blades, but it is so much easier than trying to stick down and sand down all those fabric threads!

chazmen

My Feedback: (1)

If you want a good source of silk try thaisilks.com or thaisilk.com I forgot which. I have used their silk on three planes now and have had good results. The silk I used comes in a ton of colors and you can get a bunch of samples from them. The price is a fraction of Sig and the yards are more than 36 inches wide.

there is still nothing like a good silk and dope finish as far as looks go besides that I dont have to reshrink it every couple of months.

bacothran

This is my first time using RCUniverse.com and WOW! what great information! I am a first-timer when it comes to balsa model airplanes. I inherited a 50+ year old Cosmic Wind Minnow and am in the process of restoring it. I have all the old paint removed and am "filling the holes" and sanding it now. When my now-deceased uncle first built this plane he didn't use any type of silk except as wing coverings. He simply painted a primer right on the wood. That is what I was preparing to do until the helpful hobby store man told me to different. Actually, he wasn't really helpful and not real nice either. But he did get me thinking about covering the plane with a silk-type material. Being a novice, and after reading all the responses, I think I'll pursue the Sig Koverall and Dope method. This plane has lasted 50 years and I've discovered that it is a rare model. I want to "do it right" so it'll last another 50 years. Any information will be greatly appreciated.
Thanks,
Barry

VoughtF4U

My Feedback: (1)

I am getting ready to cover a Dynaflite Super Cub and a Hostetler Gee Bee R2. I am using some leftover ceconite and paint from when we recovered our full scale cub. However, i don't have enough to finish the Gee Bee with. I am planning on buying some Sig Koverall. However, I have a couple of ideas I thought I might ask about first.

First, has anyone used exterior grade latex paint to paint the Koverall instead of doping it? I have heard that this seal the cloth like dope will and comes out just as light with great results. I have heard you do not have to dope the surface first to seal it. Just spray it with a latex primer and then shoot one or two coats of latex paint for color. I am looking for someone with experience to back this up though before I try it on my Gee Bee.

Second, has anyone ever used a polycrylic coating and the Sig Koverall in place of fiberglass cloth? I am wanting to use dope to stick the Koverall onto my fully sheeted wings, and then use a couple of thinned layers of polycrylic over the koverall to make a really hard surface. This will then be painted with latex paint. I can't think of any reason why either the latex paint or the polycrylic wouldn't work with ceconite or koverall, but maybe one of you guys have experience and can confirm this or let me know why it didn't work.

Sport_Pilot

IMO, Koverall is a bit heavy for a AstroHog. Sig silk is light, probably lighter than monokote. Then there is the Thai Silk but the one example I have seen is thicker than Koverall! You can get some very nice examples of silk at the fabric store. Look at the crepes and chiffons. Don't get the krinkly stuff, don't ask me how I know.

Sport_Pilot

You can get fiberglass as light as .5 Oz/ Sq. Ft. which is lighter than Koverall so I don't see the value of this. However I have used Koverall over an open area and put fiberglass over it. So I guess you could cover your wing with Koverall and glass it too!

jettstarblue

Everyone,

About the only thing I'd like to add here is, try Balsarite to stick down the Koverall-use it like dope, or let it dry and use it as an iron on. (Paint it on, let it dry, lay on koverall, iron down.)
Also post #16 says it all when it comes to polyester fabric covering. I buy and use the lightest cloth on my full size, and models. Very cost efficient.
Also, on the subject of F/G versus polyester, I tried to use Ceconite and finishing resin like you would with fibreglass, and the results were, horrific. The ceconite does not accept the resin like F/G and you will have a de-lam sitiuation on your hands in no time. In the world of composite planes, this is known as peel-ply, you put it on over your last fiberglass layup, and when it's set you peel it off and you have a perfectly preped surface for your next layup. (wish I had known that before) In the same vein, F/G is not a suitable covering over open areas, even though you can get some really light F/G cloth, it doesn't work.

Jetts

Flyboy Dave

My Feedback: (21)

Yo Guys....If Koverall was used as a substitute for
thin glass cloth, and doped down good with two or
three coats....could automotive spray enamel be
applied to the piece....with or without primer ???

Dave.

FHHuber

I'm an old-time silk and dope user. and I'm under 45...

I buy my silk cloth from www.thaisilks.com 10 mm "Habotai" is what I use the most of. I get it white, hand wash it, rinse thouroughly and immediately apply it. (why get it wet twice?)

For best results you'll use a combination of nitrate and butyrate dopes. Nitrate gives better adhesion and better grain sealing. It also seems to give a more even shrinkage (but that may be a side effect of the better adhesion and my techniques...) The butyrate is required for fuel-proofing if using a glow engine.

Full scale aircraft dope is fine for models... usually its nitrate. (when you can find the stuff... They're all switching to Stitts and similar, which is NOT dope.)


You can use the Stitts method too.. its a dacron, glued on and then shrunk with heat. (I've got the EAA builder's supliment explaining it... dress shop stuff is fine for models.) The paint is not necessarilly resistant to nitro... but a clear coat on top cures that.

jettstarblue

Dave,
Should be no problem. Nitrate works better to hold it down, (put it on) . Butyrate is for sealing, and shrinking. I would use primer first, or a very light wet sanding at least, before painting.
By the way, the best fuelproof paint I've used is "Painters Touch" (Rustoleum product). Goes on better than most, comes in spray, and regular cans, and lots of er, uhm, unique colors.


Jetts

Sport_Pilot

The Koverall will be heavier than Sig Silk, Sig Silk is available not custom ordered but it is expensive. There are other choices of silk though 10mm Thai silk will be heavier than Koverall. Fabric store silk thin enough to see through will be fairly inexpensive and weigh less than Koverall.

jetstarblue,

I think peel ply is impregnated with a release agent. I know from experience that epoxy and fiberglass will adhere to Koverall. I had a plane that was converted to a taildragger that kept cracking or breaking off the tail boom. The lightening holes made it too fragile. I covered the holes with Koverall and dope and covered over with ultracote to match, only to have another crack. I then overlaid the Koverall with fiberglass and have never had a problem since. So you can fiberglass open areas and fiberglass will stick to Koverall.

http://www.aircraftspruce.com/catmai...st=cathome.php

Notice that this product will work with epoxy?

Flyboy Dave

My Feedback: (21)

....one other Dumb question, if you please....
What the heck is "Dope" anyway...??? Enamel....
laquer....acyliric....?

I used that stuff before Mono-cote was born....
and I still dont know what the heck it is !

Flypaper 2

It's a form of laquer. Been around since ww1

Flyboy Dave

My Feedback: (21)

Would it be better then to paint over it with laquer
and laquer clear-cote ??? Or would you
even need primer.

Another dumb question....do car painters use one
primer for a laquer job, and another for an enamel
job ? (sorry for being such a dummy) :stupid:

Dave.

Flypaper 2

You could use Butyrate dope as a finish as it is fuel proof and glossy.

Sport_Pilot

It is also compatible with acrylic lacquer used to paint automobiles which is also fuel proof. Most paints will go over a lacquer primer which most primers were till the EPA got into paint vapors. Now days the body shops must use a primer made specifically for the paint used and must meet EPA specs.

Nitrate dope which is what they used in WWI till the 30's is not fuel proof and highly flammable even after drying. In fact dried nitrate cope is the same substance as gun cotton an early form of smokeless gun powder. In fact historians have now decided that the Hindenburg did not explode because of leaking hydrogen gas but because of the aluminum nitrate dope used on the fabric covering. Aluminum and nitrate is a good solid rocket propellant! I remember years ago soldering a control linkage on a control line plane with a propane torch. The plane had been primed with nitrate dope but not painted over. The flame didn't even touch the surface but the plane went poof in a quick yellow flame scorched the entire plane and burned some of the silk and between the wing flaps at the hinge line. Good thing I had some water handy that I was using to shrink the silk.

jettstarblue

You can get colors of dope. Sig is very good, aerogloss by Pactra is O.K.
If you put the colored dope over top, you won't need a primer.
You shouldn't need to clear coat it either, unless you are going for the super gloss finish.

Jetts

Flyboy Dave

My Feedback: (21)

Ok...I was planning to dope the material down good
with about 3 coats of clear dope, and then painting
it. That's why i was wondering about the "dope", and
how to paint over it.

This is my first "real" paint job, done this year...and
it is wood....sealed with sanding resin....primed, and
painted with spray enamel....and an enamel clearcoat.
It came ok, as you can see.

However, I want to build a few planes that are completely
covered and painted the "old fashioned" way, and without
having to cover the open-framed wings with the plastics.
I have a Top Flight Cessna 182 kit, and an AK Mig 29 kit,
and a couple Bridi pattern kits that I wish to paint, and
just do my thing.

I don't want to have "spider-webbing" later....because I
applied the wrong paint....over the wrong paint.
Any, and all help will be appreciated....

Dave.

Flyboy Dave

My Feedback: (21)

Still wet....came out ok.....

jettstarblue

Dave,
That should do it, stick it down, 2-3 fillcoats, (clear) then paint or colored dope to finish. You can use just about anything over the dope base, and it shouldn't crack. Another thing is a drop or two of castor oil in the dope will keep it flexable on the open areas.


Jetts

GSNut

My Feedback: (8)

If you want strength and a lighter finish with out the extra weight of all the primer and paint.

Try this...

Apply the Sig Koverall (I have use thin CA) and get it shrunk to your satisfaction...once it shrinks it becomes very stable and will not streach unless forced to do so.

Now apply only one coat of thinned out fuel proof dope and let it dry. (Do Not fill the weave of the fabric, let it breathe)!

The whole secret to this process is this:

Now cover the Koverall with your base color in Monokote, being carefull to let the air between the two escape. So as to not have any bubbles...if you do then a pin ***** an a bit more heat will take care of it. To emulate a fabric covering just heat the monokote and using a soft cloth or miten press the monokote into the fabric weave of the Koverall. Of course you can add the stitches and such before you use the Monokote.

Ok, now that you have a beautiful 2 ply finish which is very temperature stable and almost bullet proof. Don't worry about the monokote relaxing over time as the Koverall stablizes it.

The trim colors can be applied ala your favorite method.

I wash the trim area with a lint free, soft paint cloth dampened in MEK, lacquer thinner or acetone. Do not use enamel thinner as it contains oils and solvents. Then mask off with black plastic electral (can you say the cheapest) tape or liquid mask for the insignia stuff. Or it can be trimmed with more Monokote.

I use Rust-Oleum or Testors Plastic enamels in the spray can for this.

Try it you might like it, Mikey did as do I.

From Older than Dirt!
The Old Phart!
Cheers
Doug in Denver [email protected]
IMAA 345

rustyrivet

My Feedback: (6)

Man, did I obtain a wealth of info and opinions here to ponder over, since I posted this question in November. After also consulting with Sig Manufacturing, here's the final dope method I'm using on my 89 7/8", 18lb Astro Hog:

1) Apply Sig "Stix -It" only to the perimeter areas that will hold down the covering. No other bare wood is pre treated, or doped.

2) Apply Sig Koverall, and use a heat iron to hold it down at the stix-it areas. Use heat iron over Koverall as if it were monokote, to shrink it into place and ready it for the dope.

3) Spray the koverall with a 50/50 mix of butyrate and thinner. . Apply as many cotes necessary until Koverall weave is gone.Sand between cotes.

4) Spray red and white Rustoleum Gloss paints for finish. (Which is glo proof.) I've used this paint in the past. It's cheap and readilly available at Sears Hardware.


I have been assured by Justin at Sig that neither the Koverall with a heat iron, nor the butyrate dope will shrink enough to cause damage.

I don't doubt that many of the forementioned ideas would
work, but after 10 months of building this thing I want K.I.S.S when it's time to complete it with no major screw-ups!!!

Any questions, ask for Justin at Sig Manufacturing @1 641 623-0215

Ikaros

Real Silk is recognized by burning a fibre of it.

If it smells burnt hair, it is silk, otherwise not.

There have been or still are, synthetic silks aviable too, quite usable but not as good as ordinary silk.

Silk intended for cloths are too heavy for any but the large 1/4 scale models.

If heavy silk is needed for a large model, then concider using nylon instead (cheaper).

Only drawback with nylon (besides not being suitable for small models) is that it gets fuzzy when you sand the overlaps.

Silk may warp a ligt-weight structure beyond repair if used improperly.

Main reason is that the dope might be too powerful in its shrinking properties.

I am used to think of two kinds of dope : shrinking and non-shrinking.

Shrinking dope should not be used over balsa. Exception: wing ribs. Never on a sheeted surface, never.

Shrinking power can be controlled by either mixing with non-shrinking dope or by adding a very small amount of castor-oil.

You guys can enjoy butyrate-dope for painting, I can not, it is very hard to get here.

On the other hand, I can get 1 Kg lids of super-quality Cellulose Laquer (dope) of both kinds for a reasonable price.

Cheers,
Ikaros

Ikaros

When looking at the qualitys of (OK I mention that first to please you American lads and girls)

MonoKote
Oracover (besser, jawohl)
Solarfilm Polyester (good stuff, very light and cheap, strong too)

Then concider using Litespan and stuff for small models where you would have used japanese paper (tissue hrmpf , though tissue was what made up my body) in past times.

Using a covering that requires doping other than genuine Silk made of silk worms, well, I see no sense at all except in the rare situations when nylon could come in question.

I like silk because it is strong, light, easy to make finishes on, easy to apply, easy to hide overlaps, and it is beatiful if it is not painted but only doped and protected.

It withstands 30 years or more of existance without sagging at all. It is better than real airplane covering maybe.

However, like the rest of the sinners, I quitted using it, I can no longer stand the headache when I dope it.

Cheers,
Ikaros