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Building Tips and technical articles. => Building techniques => Topic started by: Dave Moritz on November 28, 2018, 08:19:49 PM
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Greetings All:
My brother is recently trying his hand at building balsa stick & tissue airplanes after many years away from the hobby. He tells me that he glues dry silk span or tissue onto the airframes. After the glue dries, he then sprays the covering with water, and then it tightens up after the water dries off with good results. He finishes with dope in the usual fashion.
I've been applying the silk span wet and having good results also. I will admit that wet silk span is harder (for me) to handle, and can see that the dry stuff wouldn't tear, etc. He claims that he always applied it dry, back in the day, and never heard of a wet application.
Am I missing something here? Small versus large craft? Simple versus compound angles? Contest finish versus "good e-nuff"?
A couple inquiring minds await the collective wisdom here. Thanks.
Dave Mo...
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Silkspan expands when wet, then dries to the same size it was before. The one time I put it on dry no amount of tautening dope would tighten it. Every time I've put it on damp it's dried to the perfect tautness.
Different brands may act differently -- my only experience is with Sig. Doctor paper may act differently, too.
Tissue definitely shrinks. It should only go on damp or wet if you're covering a compound curve. For outdoor rubber powered planes I like to shrink it by wiping it down with a cotton ball that's been wetted with 70% isopropyl alcohol. That makes for a nice even application of just the right amount of water when the alcohol flashes off. For indoor rubber or really small outdoor planes you shrink the tissue on a frame, then cut it off, crumple it a bit, then put it on the plane. Otherwise your plane will potato-chip as the tissue shrinks.
I think I'd only use tissue on 1/2-A planes, and then I may use it double-thickness. If you go out and buy it, stick to Esaki -- all the other stuff I've bought recently has been crap.
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The old misty trick!, I do that to silkspan prior to application, and keep it just a bit moist but not dripping wet, until the edges are down. Then it can dry on it's own.
Like Tim says, tissue is a different animal, and getting an even shrink on a stick and tissue aeroplane is mission, I've only ever managed to keep wings straight by clamping them or pinning them to the workbench.
Motorman, what's your beef with using paper? You're using stuff that comes out of a caterpillars butt!
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Silkspan is made up of rotten silk threads. Not unlike expensive paper made from cloth, like our paper money.
Hmm. Come to think of it, dollar bills might be less expensive than silkspan! Too bad they come cut up into little rectangles.
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Holy-moly, there're some fine responses here!
Mr. Motorman: Appreciate your good comments. My brother and I rather see ourselves as "living history, old-timey" builders when it comes to stick built models. Believe it or not, some of this hobby's appeal is in the fussy construction, but always open to change if it becomes too bothersome.
To refine my question for the others a bit. I'm in touch with a budding, thirty-something modeler just starting out with a couple of small free-flight & rubber kits. Is it OK to tell him to apply the (paperish? or silkish?) covering dry and then shrink with water? One is an old kit and another is new. Not sure what the producers put in these old and new kits. By the way, I intend to introduce him to CL after he's had a chance to try his hand at building.
Thanks all.
Dave Mo...
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If they're rubber powered, it's almost certain they're tissue. It should say on the box or in the directions.
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Holy-moly, there're some fine responses here!
Mr. Motorman: Appreciate your good comments. My brother and I rather see ourselves as "living history, old-timey" builders when it comes to stick built models. Believe it or not, some of this hobby's appeal is in the fussy construction, but always open to change if it becomes too bothersome.
To refine my question for the others a bit. I'm in touch with a budding, thirty-something modeler just starting out with a couple of small free-flight & rubber kits. Is it OK to tell him to apply the (paperish? or silkish?) covering dry and then shrink with water? One is an old kit and another is new. Not sure what the producers put in these old and new kits. By the way, I intend to introduce him to CL after he's had a chance to try his hand at building.
Thanks all.
Dave Mo...
Dave, As was mentioned earlier; put it on "damp" not wet!
Here's what I do; Spread out an old towel (new one will get you in trouble with the wife!). Lay the silk span (or Jap tissue) on it and lightly mist it with water. Let the H2O drip, be absorbed, etc., while doping the frame work. Lay it on and carefully and smooth it down. Dope around the edges, wait for it to dry thoroughly, then dope the rest avoiding the edges. Then you can dope the whole thing for as many coats as deemed necessary.
Good luck, Jerry