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SilkSpan and Dope Repairs

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SilkSpan and Dope Repairs

Old 02-24-2004, 12:58 AM
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Al T
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Default SilkSpan and Dope Repairs

Hey Guys
Looking at a silkspan and dope finished airplane. It's seen better days, I'm sure of it, but I would like to try and save it versus covering it with heat shrink film or something. The structure is sound. Looks like it's all hanger rash.
1.The finish has a few areas were it is heavily cracking and flaking off. How easy would it be to repair and how would you recommend approaching it?
2. A few areas have the dope finish splitting open and starting to curl up. Can it be flatened, resealed and blended together and if so what would be the recommended way?
3. I see isolated spots on the wing and tail were the silk span in the open structure has been stretched and sagging. Maybe someone grabed it there a little to firmly. Can it be retightened by sanding off the dope and wetting the area to shrink it?

Any help or suggestions would be greatly appreciated.
Thanks in advance

Al
Old 02-24-2004, 01:46 AM
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Default RE: SilkSpan and Dope Repairs

Sounds like the old Aerogloss. I've seen this finish do that when applied over a non Aerogloss clear base. Or it may have been an attempt to use automotive lacquer over the clear base.

You could try to remeld the top color coats with thinner but I think it'll just make a big mess. Silkspan is still available from Sig as far as I know as is good old dope. Perhaps it's worth a recovering job using the original materials.
Old 02-24-2004, 02:59 PM
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Default RE: SilkSpan and Dope Repairs

Hi guys,
Slightly off topic but perhaps inspirational.

I just returned from the VRCS reunion at Spring hill where a fellow brought 3 newly built & absolutly beautiful silkspan & dope planes.

The Mambo RC Trainer
Veco Smog Hog
Ed Kazmirski's Orion Pattern Plane

Perhaps someone will post pics.

Good luck (Silkspan is alive & well)
Bob G
Old 02-24-2004, 04:06 PM
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Default RE: SilkSpan and Dope Repairs

If you can post pics... we can tell you if its easier to repair the old covering and finish... or strip it and recover.

I've had decent luck restoring a couple of old models using 75% acetone 25% clear dope to get lightly cracked dope to blend back together and stop minor peeling.

Because of potential incompatibility of dope thinner to the old dope formula (don't know for sure which brand was used on the model when the original finish was done... you don't want to use "Dope Thinner" Use acetone. (universal dope thinner... works with any brand, Nitrate and Butyrate)

Dope is definitely still available. Some old die-hards still love it.

for patching holes... you TEAR silkspan to slightly ovesize, and dampen the patch with water, then blot on a towel. Lay the patch in place and pant the edges down with 50% clear, 50% acetone. When that all dries, it will be a bit cloudy... paint again with 50-50, and that will go away. then paint to match the original. It will blend right in.
Old 02-24-2004, 07:09 PM
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jessiej
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Default RE: SilkSpan and Dope Repairs

[Dope is definitely still available. Some old die-hards still love it.]


I still love it, and "old die hard" is one of the nicer things I've been called.[sm=wink.gif]
Old 02-24-2004, 07:35 PM
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Jim Finn
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Default RE: SilkSpan and Dope Repairs

Doping a plane today! Yes I am old but silkspan and dope I learned after using ultracoat. I am now using polyster dress lining material and dope on a 78" wing. Lightest covering I have ever seen!
Old 02-24-2004, 08:40 PM
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johnvb-RCU
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Default RE: SilkSpan and Dope Repairs

Hi Jim. Polyester dress lining material? My daughter came home the other day with some stuff called Polytrace. It's a white polyester fabric which looks like tissue but seems to have threads in it. She told me it's used for tracing patterns. At about AUS$1 a metre the price is good compared to Airspan etc.. Does it sound like the stuff you're using?
Old 02-24-2004, 08:58 PM
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Default RE: SilkSpan and Dope Repairs

One thing wasn't mentioned very well from what I read.

Do you plan to use the model once done, or just put it onto display?

If you plan in flying it, the old silkspan will fall apart after a few uses. At best they used to indicate about ten years lifespan for the covering. Just then, go ahead and strip off all the older covering and go new again. You cannot put the natural moisture back into the silkspan fibers to regain strength.


Wm.
Old 02-24-2004, 09:26 PM
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Default RE: SilkSpan and Dope Repairs

ORIGINAL: johnvb-RCU

Hi Jim. Polyester dress lining material? My daughter came home the other day with some stuff called Polytrace. It's a white polyester fabric which looks like tissue but seems to have threads in it. She told me it's used for tracing patterns. At about AUS$1 a metre the price is good compared to Airspan etc.. Does it sound like the stuff you're using?
I like the sounds of this. If it's used for tracing patterns then it sounds like it's more paper like. If you wet it can it be stretched slightly as if you were pulling it around compound curves? Also is it pourous so the dope will bond well?
Old 02-24-2004, 09:26 PM
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Default RE: SilkSpan and Dope Repairs

Yes... if the covering has gone brittle... and you want to fly. strip and recover. (its a mess... but its educational )

The polyester material mentioned is useable. Its a bit heavier than SilkSpan heavy "tissue" when you get done. Its a little lighter than a medium silk though. the polyester can be heat shrunk after adhering it to the airframe

This is basicly the way the "Stits" covering system was developed. Someone (his last name was Stits...) decided to try a polyester dress material in place of "unbleached muslin" which was the basis of the covering on many full scale aircraft in the 1930's. The experiment was a resounding success...
Old 02-24-2004, 11:44 PM
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Al T
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Default RE: SilkSpan and Dope Repairs

Hmmm......a lot of very good points. Yes the intent is to fly the plane versus just display it. It's good to know that silkspan and dope only have about a 10 plus year life.

Any suggestions on how to make the stripping (oh yeah baby take it off...take it all off!) process easier. I recall doing a repair way back when and it came off in tiny bits. I spent a lot of time picking off little pieces off teh wook. I would sure like to avoid this again.

Al
Old 02-25-2004, 01:21 AM
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Default RE: SilkSpan and Dope Repairs

Assuming the original builder used dope to adhere the silkspan you can use acetone or good quality lacquer thinner to soften the dope in the tissue enough to release it quite cleanly. But don't just slosh it on as they may have used Ambroid or Sigment to build it with and the thinner will melt the glue as well then.

I find acetone evaporates too fast so I suggest you try some GOOD lacquer thinner from an auto paint supply outlet rather than the typical hardware store stuff. Lacquer thinner is a generic name for a soup of other basic thinners and like most things you get what you pay for. The auto paint supply stuff is the Real McCoy. In fact it's so good that a buddy of mine has had great luck using it in place of dope thinner for thinning both nitrate and butyrate dopes. But check it first for a bad reaction that produces a gelling of the dope. The brand of lacquer thinner is important in this case.
Old 02-26-2004, 12:18 AM
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Default RE: SilkSpan and Dope Repairs

Say, Bruce, the best of the auto lacquer thinners that was a favorite of the CL Stunt crowd has been D/Cd by EPA regs. Its replacement is not as good. Current recce is to use the branded thinners for painting and cheap stuff to clean up. I use Brodak dope and it loses its gloss if used with any other thinners.

The polytrace sounds like a material called Polyspan that several places sell for model covering. It is really nice once you get used to its quirks. Here's a link to some info about the stuff:
http://www.tomsbuildingservice.biz/p...r%20Tissue.pdf
I have used it and it makes a really strong covering, much better than silkspan. The disadvantage is that it doesn't do curves well. You just about have to do wingtips with patches of silkspan.

Kelvin
Old 08-04-2022, 06:26 AM
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JSlade
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Default RE: SilkSpan and Dope Repairs

Just wanted to mention that the link in the last post is now dead and that website is not longer up.
Old 08-04-2022, 07:45 AM
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You can still get model airplane dope through Sig and Brodak. Lately, I've been getting my nitrate dope from Aircraft Spruce. The price is about the same but they ship quickly..
Old 08-04-2022, 12:41 PM
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I get nitrate dope from Wicks Aircraft Supply in Indiana.
Old 08-04-2022, 01:40 PM
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Default RE: SilkSpan and Dope Repairs

Thanks for the replies guys. I've got an old Ringmaster Senior that I built about 50 years ago that's a bit worse for wear from being mishandled. Now that I've got it back and time to fix it, I was looking for tips and tricks for removing the tissue / dope covering from the airframe. Lacquer thinners is working well for that. Just have a few repairs to do next before covering the wing with the silkspan that I was able to pick up at a local shop.
Old 08-05-2022, 05:46 AM
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Default Silk and Silkspan

Originally Posted by JSlade View Post
Thanks for the replies guys. I've got an old Ringmaster Senior that I built about 50 years ago that's a bit worse for wear from being mishandled. Now that I've got it back and time to fix it, I was looking for tips and tricks for removing the tissue / dope covering from the airframe. Lacquer thinners is working well for that. Just have a few repairs to do next before covering the wing with the silkspan that I was able to pick up at a local shop.
I wonder if most folks today are aware of the difference between silk and silkspan? I hear many refer to silk as silkspan. They are very different. Silkspan is really paper, what was once called Japenese Tissue. The same stuff as is used on Oriental paper umbrellas.
Old 08-05-2022, 02:48 PM
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Silkspan is totally different from Japanese tissue, and modeling silk. Silkspan came in three weights 00, M, and GM as I recall. Silkspan is a natural fiber type paper, and has a grain like most paper products. Having a "grain" means it will tare easier one way then the other, and it will shrink more in one direction then the other. It was only available in white, although some kits had red silkspan. Modeling silk came in one yard packages in white, and a few colors, however white silk could be special ordered by the bolt for inclusion in kits, or resale. The premium Japanese tissue was Isaki which is no longer manufactured, but many free-flight modelers still have a personal stash.
Old 08-05-2022, 05:04 PM
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Question Silkspan VS Japanese Tissue

Greg,
I humbly accept your description of Silkspan and Japanese Tissue, but I scratch my head wondering what really is the "total" difference between them?. Silkspan and Japanese Tissue are both made from natural fibers, they are both considered paper, both have a "grain" and both are used to cover model aircraft.
Old 08-05-2022, 09:07 PM
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Starting with tissue. Think about tissue used in gift wrapping. Most of us refer to it as domestic tissue, because a lot of it is made in this country. Domestic tissue is available in much more vibrant colors then Japanese tissue, but is about twice as heavy. I just picked up 50 sheets of domestic tissue at Target for about $8.00 Japanese tissue is the preferred covering for small indoor models, particularly scale models that are often weighed in grams. The last prices i heard for Japanese tissue was $1.00 a sheet. Sheets of Japanese tissue are smaller then typical sheets of domestic tissue. Frequently this tissue is pre-shrunk off the model, or shrunk with alcohol to prevent warping of fragile structures. The lightest weight silkspan is about like newspaper, and the heavier grades are heavier, and stronger. The heaviest silkspan is close to silk in strength, but will tare more easily then silk. When silkspan was substituted for silk it was a common covering for ..35 cu.in. controline stunt planes in the 2+ lb. range. Generally silk would have been the preferred covering for such models, but was more expensive then silkspan. In my younger years I used a lot of silkspan because that was what I could afford.

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