rustyrivet

My Feedback: (6)

This is a lost art! So I figured I'd look for you old geeesers who know about this kind of stuff. But don't feel to bad, cause I'm 49 and right behind ya, catching up fast!!

I'm going to soon be ready to start doping my 89" enlarged Hog. ( 2 to 3 months to me is soon) I went to the LHS that had none in stock. (Who in their right mind wants to use anything except Monocote, Ultra Cote, etc) The guy there(yep, another "mature" individual) advised that I go to the everyday Fabrics store and buy it there!

He said I should obtain fabric that hasw a content which is aprox, 78% Rayon, and 12% silk.

You guys that have experience with dope finishes: What do you think about this? If I can use Fabric Shop stuff, are there other kinds of material or percentage contents to seek? (100% silk?) Or should I stick with stuff made strictly for R/C?

probligo

If you use "dress shop" silk, then get your wife to very carefully wash the silk a couple of times before you use it. The reason is that many "sewing" fabrics contain a "dressing compound" that could affect adhesion and doping. I would hope that "modelling silk" would not have the same problem.

BTW there was an article I saw years back where a guy covered a C/L stunt model using paisley patterned silk scarves. Amazingly beautiful aircraft!!

The other use I have seen is setting silk into the gel coat of a glassed wing - endless fun

rustyrivet

My Feedback: (6)

Seems easier to locate silkspan, even if my local hobby shop doesn't carry it. Thanks.

ProfLooney

Though I dont want anyone to think im in the old farts or old geezers category hehehe bu all I have ever used is silkspan randall and if you can find it I would just stick with that otherwise I would just go out get a yard of various kinds and see which works out best on some sample pieces

Joe

Flypaper 2

If its an 89 in wingspan I'd be using the silk, much stronger than silkspan for a wing that size. we used to use silk scarfs for such things but now they're mostly synthetics and you don't know what they are made of.

Kaos Rulz

I've covered aircraft using tissue paper. silkspan, and silk. Silk requires more dope to fill than does the silkspan. I've covered two 60 size Kaos's with a product manufactored by Dave Brown called Syyloft. I found it far superior as it draws tight in all directions as the dope dries. Other materials have a tendency to shrink in one direction more so than the other. This skyloft fills with only 3 light coats of clear before the color can be applied. Once finished, this stuff is very resiliant. Obviuosly this stuff weighs more than monocoat, but will easily outlast it.

ED

probligo

I would second the comments by Flypaper.

The likes of silkspan are not (if I have got the right or same trade name here) a woven cloth.

It is an acrylic fibre reinforced plastic film. That is the reason for the "grain" referred to in the other thread on the topic.

True silk (as a woven cloth) is quite a bit stronger and certainly more expensive.

The only alternative that I would consider would be terelene, as light as possible like (heheh showing my other interests here) spinnaker cloth for small sailing dinghies. Some terelene sail cloths have been "heat sealed" which effectively does the doping and everything for you. I have never tried this kind of cloth on any model.

Nylon is NBG because it is too stretchy and it will continue to "give" over time. It is nice and cheap but it is not for the plane that you want to be flying in 5 years time.

gfinan

Randal

Sig Manufacturing still sells both heavy and lightweight silk. Their web address is www.sigmfg.com.. I prefer the Sig Koverall polyester myself, it's a lot cheaper and can still be applied with dope as I do. If you prefer they also make a product called Stik-It that you can apply to the wood so you can iron the fabric on, although it still requires top coats of dope. Hope this helps.

rustyrivet

My Feedback: (6)

Guys,
I haven't hit the fabric store yet, but went back to the hobby shop to talk to a 83 year old geeser who works there only on Thursday and Fridays. I think he spends the rest of the week charging his batteries to keep his body functions going.( God Bless those batteries. What a great generation he's from!)

He offered polyester cloth Sig "Koverall" in stock, as well as the medium and heavy grades of "Silkspan". He advised if I did choose the "Silkspan" to go with the "GM" intermediate grade, instead of the heavier grade "GSM".

It seems too that "Koverall" can be used with butyrate dope alone to fasten it to the frame. And I don't have to buy "stick-it" adhesive if I'm already using butyrate dope. The only thing that concerns me is why this Koverall stuff shrinks with a heat gun?? Now I'm worried I'm getting involved with a material that will change in time, or sag like Monokote.

Pure silk at the fabric store now seems unecessary.

So the question now is : Should I use medium grade "GM" silkspan, heavy grade "SGM" silkspan, or Sig polyester "Koverall"?

gfinan

Randall

I would use the Koverall. I don't use the Stix-It myself, I'm more like you, if you have to use the dope anyway then why not use it to adhere the fabric to the wood . I've been using this technique for years without a problem. Yes, the Koverall and for that matter the silk also is heated to shrink it. After it is coated with dope it will not loosen up like Monocote, etc. It does have a nice characteristic though, if you get a ding in it you can use a heat gun to shrink it out. The silk is also a LOT more expensive than the polyester Koverall. Silk is used more for the WW I era of aircraft. Let me know if you have anymore questions. Good luck, Greg

gfinan

Ed Stefan

Hey Ed, is that you up there, I just saw your post. E-mail me sometime at [email protected]. Do you believe they are calling us old farts?

Greg Finan
Perry RC/Dixie Aeromasters

rustyrivet

My Feedback: (6)

Greg,

When you compare the Koverall to "Silk" . Are you referring to fabric store silk, or Sig Silk Span? If you have used the Silkspan, how do you compare it to the Sig Koverall stuff?

That "SkyLoft" stuff Ed mentioned sounds good, but I'm trying to work with what the LHS stocks. So I'm leaning to Silkspan or Koverall.

PS Personally I prefer to be called geeser myself. Don't feel bad though. Fart or geeser or whatever, they just taint calling me "kid" anymore.

pabdoc

The last plane I covered was a Sig 1/6 scale Citabria, and I used Sig "Super Coverall." It was so easy to work with, that I plan to use it almost exclusively in the future. I bought a big roll of it ten years ago, and still have quite a lot left....are they still selling it?

gfinan

Randall

I use the aircraft silk such as Sigs. The dept, store type has different weaves and has sizing and/or starches on them to prevent wrinkling on the shelf. Please don't get me wrong, the dept store types are usable but don't preform as well.

Silkspan is actually a paper covering with threads of fabric in it to make it stronger (something like the paper that money is made of). Silkspan also punctures and tears a lot easier than the fabric coverings. I used to use silkspan on smaller airplanes where weight was a concern. It is not recommended for models the size of yours.

I would stick with the polyester Koverall, it works just like the silk but is far less expensive. Polyester is what the full sized airplane industry changed to about 60 or so years ago when they stopped using silk. I think with the Koverall you will end up with a nice looking and durable finish. Good luck, Greg

P.S. I have to side with you, geezer isn't as bad as old fart

GeraldO

My Feedback: (2)

Silkspan is not strong enough for an 89" hog. Also someone said that silkspan "is an acrylic fibre reinforced plastic film." this is false. Silkspan is a tissue paper like material and is not an acrylic.

The best silk fabric for covering is "Esaki" silk made in Japan. Sig sells it. It is VERY expensive but will save you tons of frustration if you decide to go the silk route. It is specifically designed for covering model planes. Stay away from K&S silk which is cheaper, made in China, doesn't stay shrunk very well once the dope hits it, and is heavy.

The Esaki silk is so light it feels like it weighs nothing. Yet it is very strong. It will shrink with water and stay shrunk even after doping. Another post said that silk shrinks with heat. This is not true. It shrinks when heated but as soon as it cools it relaxes right back to where it was. So you need to apply it wet, get it reasonably taught and smooth before it drys, and then it will tighten up like a drum when it dries.

Besides the traditional silk & dope, an interesting variation I have tried is to use lightweight silkspan under the silk. First cover with silkspan using the conventional method of applying it wet. It will shrink up nicely. Then apply two thinned coats of dope. Next cover with silk applied wet and dope it down on the edges through the wet silk. When it's dry and tight, apply as many coats of thinned clear as necessary to seal the weave, probably 2 to 3 coats. Then paint as desired

The advantages of this method are that the underlayer of silkspan makes it easy to smooth out the silk as it serves as a "base". Also since the silkspan seals with less dope than the silk, it takes fewer coats on the silk to seal it and you won't get the "puddling" of the dope under the silk that you can often get otherwise. Finally, the covering is VERY strong, practically bombproof. But it is surprisingly light. If done right it can weigh about the same as a heavy grade of MonoKote.

By the way Randall, I'm not as old a "geezer" as you are.

Jim Messer

My Feedback: (2)

I've only been modeling since 1937, so that probably puts me in the "old geezer" category, but I build, fly, and can still compete with dignity. Now on the subject of covering: I only use a dacron fabric that is marketed under such names as Ceconite; Stitts Polyfiber, and Sig Koverall. The first two fabrics are FAA approved for use on full scale aircraft, and they come in different weights.
The lighest range from 1.6 to 1.8 oz./sq. yard. But I go to Aircraft Spruce & Specialties and purchase their "non-certified" dacron, as it is about half the price. I apply the fabric to the framework with regular nitrate dope that has been left open, so as to thicken somewhat into glue. After the fabric is applied, it is heat shrunk using either an iron - or a heat gun. If you use a heat gun, be careful not to overshrink. For first learning, I recommend the iron.

Once shrunk, I dope with three coats of nitrate dope thinned 50/50. After that - paint as desired.

gfinan

Jim

Thanks for mentioning that shrinking with a heat gun is not the way to go.. I forgot that in my last post. Another problem with using the heat gun is that it is too easy to warp the airframe with the excessive shrinkage. I'm glad someone finally backed up my assertion that Silkspan is a paper type of covering.

Randall, as I said earlier, your best bet would to go the with the Koverall method. I'll attach a photo of what Koverall looks like when finished on the control surfaces of my P-40E. Best of luck

rustyrivet

My Feedback: (6)

Gentlemen,

Well, I'm going to try to do business with the LHS who has already sold me the gallon of Brodak's Butyrate dope, and currently can provide me with one of the two mentioned coverings they carry in stock.

It seems the general consensus here is that even the heavier grade of Sig Silk Span designated with the catolog # GSM, is inferior to the polyester Sig Koverall. The suggestion that real silk can be special ordred from Sig is probably over kill too.

So therefore, Sig Koverall it will be!

I'm going to try to stay the course that I am familiar with as when I doped my first Guillows plane some years back with tissue paper. I think Sig Koverall and Butyrate dope will have me feeling at home. This way hopefully, if I keep it simple, and don't start experimenting with special name coverings, fabric store silks, double applications, heat guns, etc., maybe I won't screw up a 12 month long project.

I read over and thought about each and every post and appreciate all the input. I really got a good feel now for what is a good course to follow, and what is best to avoid.

-Randall

rustyrivet

My Feedback: (6)

Greg,

I enlarged your photo to see the close up detail. Boy, do you sure know how to apply that Koverall! I can only hope my simple red and white "Hog" will come out with as nice a finish.

Thanks again.
Randall

PS And you sure know how to rivot and paint over it too!

gfinan

Randall

I think you are going the best route. These methods have been around for some time and work great. The only downside is that it takes longer than the iron on films.

Take your time and you will have a great finish on your hog. Let me know if you need any help, my e-mail is below my signature. Best of luck, Greg

WMB

My Feedback: (1)

Just another question; If the control surfaces are solid balsa, would they get covered with koverall? Mike

Jim Messer

My Feedback: (2)

Yes - cover the solid surfaces.

RCToon

WOW never thought anyone covered silk and dope these days. I come from India where you dont get all the modelling stuff you get in the US. No chance of getting any iron-on covering there. I remember doing C/L stuff with my dad and covering planes with silk. The silk used to be a not being used moms silk saree (a traditional dress in India) or something bought from the local cloth store. The criteria used to be, the grain should be close together so the dope wont seep through! Doing aeromodelling in a place like India (at least 20years ago, I have moved since) was a different kind of art. We made bell cranks from metal sheets, canopies from plastic bottles, mixed our own fuel and repaired our own engines. I have lapped many many pistons for our 2.5 cc and 3.5 cc diesel engines. Remember Allen Mercury anyone? Or DC or ED engines?
We did'nt cover the solid surfaces, just doped them 2 or 3 coats, sanded and painted with nitro cellouse paint! Those were the days, cant get the smell of dope and thinner out of my nose even today.....
btw silkspan is not silk its paper based.

jorgeelizondom

My Feedback: (1)

Is there documentation somewhere on the web with a "How-to" cover with Koverall?

gfinan

George

The only thing I can think of is to get a Sig catalog. It has a complete How-To in it for the dope/Koverall technique. It is really easy to do. If you don't want to buy their catalog, e-mail me and I'll copy the pages for you (Sig shouldn't mind because you'll be using their materials anyway)