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Building Tips and technical articles. => Paint and finishing => Topic started by: Mike Griffin on August 17, 2019, 04:57:34 PM
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I have never used non tautening dope and was wondering if it will shrink the tissue tight?
I am using colored SIG Tissue because I like the translucent appearance. I have used this before with tautening butyrate on wings and solid sheeting surfaces with no problems.
I am now building a plane that has built up flaps, stab and elevator. If I cover with the tissue and use NON tautening dope, will the tissue shrink tight enough? I am afraid of warpage using tautening dope.
Thank you
Mike
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Keep in mind I build small...1/2A. Non-taughtening dope will shrink the tissue, just not very aggressively. As long as the tissue is wrinkle-free at installation/application time, and snugs up when water-shrunk, then it should snug up just a bit more later as non-tautening dope is applied.
On a couple of my models, the tissue sagged upon initial application, but then tightened back up over night. Another application, and it tightened back up over night again. After a few cycles, the tissue will have enough dope that it won't get so soggy on subsequent aplications of dope, so the bagginess stops. I notice this most on the models I use gift-wrapping tissue on. The behavior isn't as extreme on models covered with "real" model tissue since there is a grain that can be leveraged for it's shrinking properties.
My worst offense was in my 1/2A Mosquito...I need to post the damage on the RCG thread for that one. It looked good on initial papering. But then it bagged during the sealing phase. I got too "ambitious," and really laid the dope on. Each coat bagged...a little less each time. The last coat didn't change much beyond the previous one, do I stopped for the night. The next day I checked hoping to find tissue drum tight...which I did see. But it also curled up the trailing edge of the outboard wing! Patience would have gone a long way on that one.
I may try to mix non-tautening with tautening hoping for that middle ground between a sloppy bag and a Pringles chip.
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As long as you shrink the tissue beforehand, yes, non-tautening (Sig Lite-Coat, in my experience) will work just dandy. I mostly know this from rubber-powered models, but there it is.
I wouldn't go very big on a model covered with tissue without either doing tissue over mylar (which I've never tried, but which the free-flight guys seem to like), or double-coating with tissue (which I've also never tried).
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Keep in mind I build small...1/2A. Non-taughtening dope will shrink the tissue, just not very aggressively. As long as the tissue is wrinkle-free at installation/application time, and snugs up when water-shrunk, then it should snug up just a bit more later as non-tautening dope is applied.
On a couple of my models, the tissue sagged upon initial application, but then tightened back up over night. Another application, and it tightened back up over night again. After a few cycles, the tissue will have enough dope that it won't get so soggy on subsequent aplications of dope, so the bagginess stops. I notice this most on the models I use gift-wrapping tissue on. The behavior isn't as extreme on models covered with "real" model tissue since there is a grain that can be leveraged for it's shrinking properties.
My worst offense was in my 1/2A Mosquito...I need to post the damage on the RCG thread for that one. It looked good on initial papering. But then it bagged during the sealing phase. I got too "ambitious," and really laid the dope on. Each coat bagged...a little less each time. The last coat didn't change much beyond the previous one, do I stopped for the night. The next day I checked hoping to find tissue drum tight...which I did see. But it also curled up the trailing edge of the outboard wing! Patience would have gone a long way on that one.
I may try to mix non-tautening with tautening hoping for that middle ground between a sloppy bag and a Pringles chip.
Thank you Jim.
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As long as you shrink the tissue beforehand, yes, non-tautening (Sig Lite-Coat, in my experience) will work just dandy. I mostly know this from rubber-powered models, but there it is.
I wouldn't go very big on a model covered with tissue without either doing tissue over mylar (which I've never tried, but which the free-flight guys seem to like), or double-coating with tissue (which I've also never tried).
Hi Tim,
This it the Heavy weight tissue that SIG sells and it is the weight of the old and good medium silkspan we used to be able to buy. I covered a Ringmaster 576 in it and it worked just fine. I bought some in yellow and orange and both look really good when clear doped and then shot with clear. I have one Syray that I covered with this stuff (doped in down) and then covered it with transparent SLC and it look great.
I applied the tissue damp and let it dry and then started doping it.
Thanks Tim for the help, appreciate it.
Mike
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I applied the tissue damp and let it dry and then started doping it.
You might want to try applying some on a test panel -- most tissue-tissue goes on dry, sags with water, and then shrinks up nice and tight when it dries. To put it wet onto anything but a really curvy surface is to risk it getting too tight.
It sounds like you met with success, though, so that's good.
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Works fine for me. Usually on silkspan.
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Did middleweight tissue cover job last night .
Atomiser bottle water on wing tissue , goes taut . Tailplane threw it on dry , then sprayed . Ten times the slack , damp .
Thus , it could vary . a coat or two of tautning / shrinking . At least on the open - tissue bays . BUT the starved horse leading edge sheeting
and uneven fuselage , from salubrious latherings , with the shrinking .
Still get visions in the minds eye of someones small scale rubber shrunk crocked deformed thing , from the youth .
Was a pre coloured all sheet Piper Cub available . No Dope required . Threw a slot car motor in & used it electric round the pole .
ON THE OTHER HAND , the P-51 covering , while smooth , is not tensioned on the open bays . Where I used Non Shrinking exclusivly .
Throwing multi coats of shrinking on anything in a short time , is likely the shrinkage will make a pgs breakfast of it tho ,
Im thinking one or two coats , of the six or eight , could be tautning . Pref just aimed at the open bay tissue areas .
CAPPING STRIPS im pre dopeing & block sanding with NON SHRINKING . With no bothers wotsoeva . Undoped as per olde pomme advice they stick out like a sore thumb .Even 1/8 or 3/32 ribs im using a pin striping brush , about five coats ,and a plank sand with 180 / 220/240 .
Spraying the first few coats , drish , so theyre not ' WET ' to avoid the covering pulling into around the rib edge . Seems entirely succesful so far .
Getting good tissue here in Aus. is somewhat of a swine these days .