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Oct 23, 2018, 11:53 AM
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Discussion

Silk and dope wrinkles


Hello all, this is my first time attempting a silk and dope covering job. I started covering the stabilizer of my recent build, I got up to the part where the silk is tacked down around the frame on both sides. After the silk had dried, it was pretty tight on both sides with out any wrinkles. I wait maybe half an hour and I go to apply the fill weave coats. I brush on one coat on one side and let it dry and I notice wrinkles begin to form. I do the other side and one more coat on each side. There are wrinkles going cordwise down the bays of the stabilizer. Does anyone have tips on doing the fill coats, to reduce the wrinkles? Thank you.
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Oct 23, 2018, 12:36 PM
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rchopper56's Avatar
I'd wait, your dope may not be dry enough yet. I am assuming that you use water to shrink the silk first before doping.
Oct 23, 2018, 12:47 PM
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Originally Posted by rchopper56 View Post
I'd wait, your dope may not be dry enough yet. I am assuming that you use water to shrink the silk first before doping.
Yes, the silk is wet and I apply the dope on the frame while the silk is still wet.
Oct 23, 2018, 06:47 PM
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rchopper56's Avatar
Did you use†butyrate or nitrate dope? I have always used butyrate because of it's shrinking qualities. I had a silked wing that wrinkled beyond my expiations so I put it in storage. Came back to it around 4 weeks later and the wrinkles were gone.

Gene
Oct 23, 2018, 07:42 PM
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Quote:
Originally Posted by rchopper56 View Post
Did you use†butyrate or nitrate dope? I have always used butyrate because of it's shrinking qualities. I had a silked wing that wrinkled beyond my expiations so I put it in storage. Came back to it around 4 weeks later and the wrinkles were gone.

Gene
I used both nitrate for the initial application of the silk and the fill coats. Will get some butyrate and try that on the fill coats. Thanks.
Oct 23, 2018, 08:58 PM
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I silk and doped several planes in the 1970’s. A year or so ago I bought some silk from a supplier recommended here on RC Groups. (habutai ?) I doped the balsa wing with three coats of clear tautening butyrate. I wetted the silk, pulled it tight in all directions, then applied butyrate dope thinned 50/50 about three times around the perimeter and set the wing aside. The next day the silk hadn’t shrunk even slightly. In fact it was looser dry than when applied wet even though it was securely tracked down all along the perimeter. I brushed three or four coats of 50/50 on the open wing bays and still didnt get any shrinkage. All of the work was performed in 75 degree room with the A/C running. I doped another wing and put it out in the 90 degree Texas sun and still didn’t get any shrinkage. I finally stripped the silk of and went with silkspan. I found that I had to hit the wet dope with a blow dryer to get any shrinkage and make the silkspan tight. Several members said the silk nowadays doesn’t shrink like the silk in the 70’s. I don’t think the dopecwas bad and never figured out the problem.
Oct 23, 2018, 09:02 PM
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Cherokee Flyer's Avatar
They are selling pre shrunk silk, that might be what you got. I got some by mistake and it never shrank.

L.
Oct 23, 2018, 09:44 PM
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I read somewhere that the silk from https://www.thaisilks.com is pre-shrunk but the silk from dharma (https://www.dharmatrading.com/fabric...botai-5mm.html) is not pre-shrunk. The silk I have is from dharma trading. I got really good shrinkage after I did the frame coats. The wrinkles started forming once I applied the first few filling coats.

One thing I realize now is it may be due to the grain of the silk. I applied it spanwise but I noticed on open bays where the grain runs straight, I do not have wrinkles. On open bays where the grain is wavy, I have wrinkles. So I think I need to be extra careful to make sure the grain is super straight when stretching the wet silk over the frame.
Last edited by ianherbert; Oct 23, 2018 at 09:50 PM.
Oct 24, 2018, 05:48 AM
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I bought my silk from Dharma Trading and made sure the grain was running the span of the wing. If I remember correctly, the Dharma info said my silk would shrink 4 or 5 percent in length.
Oct 24, 2018, 04:30 PM
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Though I've never used butyrate dope, but only nitrate, I seem to recall there's a big problem when using one on top of the other. Can't remember which way round though. Probably best not to mix the breeds.
Oct 24, 2018, 04:42 PM
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I’ve never used nitrate dope, only butyrate
Oct 24, 2018, 06:33 PM
A man with too many toys

Nitrate dope and butyrate dope


Use Nitrate Dope to seal the fabric. It sticks better and makes the wood surface harder and more durable. After a few coats of clear nitrate you can paint with anything - color butyrate, Krylon spray, lacquer, enamel, or anything else.

The classic finish is to apply clear nitrate, butyrate color, after it cures for a week spray on a couple of thin coats or butyrate clear. Butyrate is not compatible with other paints so you can't paint butyrate clear over anything except butyrate dope or nitrate dope.

I get my dope from SIG. SIG Supercoat is butyrate dope. https://sigmfg.com/collections/cover...ints-and-dopes

.
Oct 24, 2018, 07:32 PM
Owner of CFC Graphics
Quote:
Originally Posted by Hoot View Post
Iíve never used nitrate dope, only butyrate
Kudos Hoot!

I choose to make my life as simple as possible using silk and dope to cover my models,

Here's what I do.

First of all, I never need or use nitrate dope for anything. Yes, I tried it .

Randolph Dope products? I tried them.

Been there done that also with Randolph Dope.

I switched to Sig products on the advice of another modeler. This was 2012.

Immediately, using Sig products, I noticed a world of difference.

I sold all my Randolph Dope and thinners to a modeler that wanted the stuff. His decision.

I would only use Sig dope products.

Application of applying silk?

It's just about the same as it's been for ever. Or is it?

I used to apply silk the traditional way, damp, and had great success with a few models. Only difference is I pulled it really tight, religiously, towards the tip and pinned it. Many pins. Sometimes some on the LE and TE and some at the fuselage.

Eventually, with some experimenting, I'm now applying silk in a manner in which it's NEVER been applied before. I've already taken criticism for this by some, but so be it. There are many Old Time modelers set in their ways that still have much to learn.

I'm an Old Time modeler also but I'm not set in my ways. I learn fast.

I like testing methods, old and new, just to see if there's a better way.

AND FOR ME THERE IS!!

I apply silk dry with CA. And I've mastered the technique and the silk comes out perfect. I will never apply silk wet with dope again.

I convinced a flying buddy of mine to try my method and now he swears by it. He'll never use wet silk and dope again.

Sure, I had to explain the method and technique to him, but he did it and he's now sold! Wow! A modeler in my corner.

If anyone wants technique info, I'll be glad to carry this further.

Here's my silked models.

The Gee Bee R-3, I used CA.
The ARGO 2, I first used silkspan and dope but removed it, I then used silk and CA
The Gee Bee Z, fuselage and tail feathers, I used CA.

Here's other products I've had great success with.

Deft Wood Sealer lacquer. Minwax Polycrylic water base. Some of this stuff is on some of these models.
Oct 24, 2018, 08:25 PM
Registered User
Aviojet, I've always thought that control line flyers had some of the most beautiful finishes ever seen on model airplanes. Yours are no exception.

I've covered and painted models and full scale with Pactra, Aero-Gloss, SIG and Randolph. They all work. The only issue I've had is that Randolph is gasoline proof but it isn't glow fuel proof. A coat or two of SIG clear over it does no damage and prevents glow fuel from softening the finish.

NItrate first, then butyrate. Nitrate won't stick to butyrate. I've always adhered with nitrate and sealed with clear tautening butyrate, then go to nontautening clear with aluminum powder before colored butyrate. The aluminum powder is necessary for UV protection in full scale planes but in models silver dope can be substituted as either gives an even, opaque base for colors. It's especially helpful with very transparent colors like yellows and oranges.
Oct 25, 2018, 04:30 AM
Owner of CFC Graphics
David,

Thank you for the compliment.

With all due respect, you're working harder than you have to on finishing. Forgive me for saying this.

Here is the issue, ten modelers will finish a model 10 different ways and argue that their way is the best. I don't argue but I explain and show my results in depth.

BTW. I did R/C for just about 25 years probably more, pattern and scale , I've only been in CL 9 years or so. Seems much longer.

A few guys in Brazil, who produce world class models, one does work professionally, are using a 2 part white auto primer. They also use 2 part auto putty, auto base coat colors and a 2 part auto clear coat. I don't think they use silver as a base and I can't imagine why they would? They also wet sand and polish.

I use white aerosol can primer and a gray putty right out of the tube. My days, a lifetime actually, of using professional spray equipment is long over and well behind me.

I will NEVER wet sand and polish a model. EVER.

Just a final 2K auto clear coat, two actually, and I'm done. Yes, aerosol cans.

BTW. I strongly believe a "World Class" finish can be obtained using simple aerosol cans, "If you know what you're doing."

As far as color, I use absolutely no color dope. As I said, R/C I used auto paints and for CL I now use aerosol cans.

ALL my models are painted with aerosol cans.

Well, a bit of air brush if needed for detailed areas.

I live by this rule. "There is no paint product that is 100% fuel proof unless it's a 2 part mix." Reason I started using 2K auto products way back in the early 80's on my pattern ships.

BTW. Every model I have, set up for IC, I'm selling. I'm going electric. But I'll still be finishing my models the same way.

Here's a few more of my models. These are posted here and there in Forums.

For Ian, silk span on all but the ARGO. Silk on the ARGO applied with dope. Finish is all aerosol cans.


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