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Author Topic: 5 coats of dope and covering is still not drum tight...  (Read 809 times)

Offline Charles Meeks

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5 coats of dope and covering is still not drum tight...
« on: October 07, 2017, 06:44:20 PM »
I covered my Sterling mustang with a covering I got with some kits off of Ebay.  It is called Midwest Microlon.  It is an older synthetic silkspan.
I put on 3 coats of clear Brodak Butyrate thinned 50/50, then applied the covering using the same 50/50 dope.  I now have 5 coats on and while the covering has shrunk it is not drum tight and does not feel "solid".  Do I just need to keep putting on coats till I get there or will the solid feel only occur when I put on color or a filler coat?  This is my first open bay wing so I am trying not to mess it up.  I put on the coats at least a day apart if not two. 
I appreciate your help.
Best Regards,
Charles Meeks HB~>


Offline Gerald Arana

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #1 on: October 07, 2017, 07:24:33 PM »
I don't know what "Microlon" is but I can tell you this: I just covered my T.F. Buster with DocuDoc and it is great and cheap! Just like the old silkspan we used to use in the '50's.

Put on wet and doped. Very cool!

Jerry

Offline Avaiojet

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #2 on: October 07, 2017, 07:45:01 PM »
I'd keep adding dope, a few more coats, you might get lucky.

CB
Alpha Mike Foxtrot.

Owner of CFC Graphics. "Model Airplane Graphics from a Model Airplane Builder."

"No one has ever made a difference by being like everyone else."

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Offline Charles Meeks

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #3 on: October 07, 2017, 08:13:46 PM »
Thanks guys for the help.  I will keep adding dope. I am new to this and I am learning the pattern.  Avaiojet, you are my favorite poster on Stunt Hanger.  I am geeked that you replied to this.  I will try to get some pictures posted soon.

Best Regards,

Offline john e. holliday

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #4 on: October 07, 2017, 08:21:43 PM »
Depending on how thin the dope is and if its butyrate it may take as many as 8 or more coats of clear.  Never heard of Microlon .  But I have used many types of covering on open bays.   But with my new way of finishing I will not be using dope any more.  One of my planes is a  good example of not using dope under the spray paints like Rustoleum. 
I was always taught to respect my elders, but it keeps getting harder to find one.
Today I broke my personal record for most consecutive days lived.
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Offline Avaiojet

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #5 on: October 07, 2017, 09:48:51 PM »
Hi Charles. Stop adding dope and let each coat dry for at least 24 hours in a warm area. It needs to gas off. Adding dope only makes the under coats soft and the covering will droop.  Place the model in the sun, assuming you don't have our rain, and let it sit there for a few hours. Once the dope has gassed off, 96 hours or so,  the covering should be tighter..   Doping is one part of model building that should not be rushed, unless you are building a "beater" for just horsing around. H^^

Charles & Charles  ;D I like this guy already.

Ty, With all due respect...

I dry my Sig dope quickly with a heat gun, coat after coat. You've see my models. Not one issue anywhere on the model, and the 007 Flite streak has been completed for what, three years.  LL~ LL~

I'm not telling anyone to do what I do, but it works for me. Speeds everything up and saves me time.

Nothing I do is recommended that you do at home. If so, only at your own risk.  LL~

Charles
Alpha Mike Foxtrot.

Owner of CFC Graphics. "Model Airplane Graphics from a Model Airplane Builder."

"No one has ever made a difference by being like everyone else."

Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten.

I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.

"Ya gotta love it when a plane comes together."

Proverb 11.9  "With his mouth the Godless destroys his neighbor..."

"Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Offline Avaiojet

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #6 on: October 08, 2017, 12:56:32 AM »
Yes, but you are a professional painter. I have no idea the experience of the person asking the simple question and answered based on my years (63 years off and on) of building and flying models.
He may not have a heat gun, 5 coats and it's getting heavy. He wants to fly his. Yes, yours are beautifully finished, but Charles, yours just sit there as art, not fly. H^^

Ty,

Charles put the coats on a day apart he said. At 50-50 you would think the stuff would dry quite well applied a day apart?

Early on I remember having difficulty with Randolph Dope products. Nothing serious, but enough for me to switch over to Sig.

Like magic, the issues went away with the Sig products. I mentioned this once in a Thread. I sold the Randolph Dope and I believe some Randolph thinner to a modeler on SH. Can't remember who?

I'm now staying with Sig products for all my silk. Be hard pressed to get me to switch.

FYI. I do think about getting something in the air besides the stuff I have ready to fly.

You were so polite about mentioning that I don't fly my models, how can I resist kindness like that? Can't actually. I believe you just gave me good reason to put one of these things in the air.

Kindness goes a long way Ty.

I'll see about getting one of these NIB OS LA 46 broken it and probably get the Stuka in the air first.

Thanks Ty.
Alpha Mike Foxtrot.

Owner of CFC Graphics. "Model Airplane Graphics from a Model Airplane Builder."

"No one has ever made a difference by being like everyone else."

Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten.

I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.

"Ya gotta love it when a plane comes together."

Proverb 11.9  "With his mouth the Godless destroys his neighbor..."

"Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Offline Dan McEntee

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #7 on: October 08, 2017, 07:49:24 PM »
   I don't know what Microlon is but it probably has a grain or direction the weave runs in, and you may have it running across the wing instead of span wise. If so it may never shrink up enough. It may also be that it needed to be water shrunk first, or heat shrunk first. If it didn't come with directions or they were not followed and it was applied incorrectly and tightened up properly first, you will never get it to tighten up with just dope. Applying heat with a possibly explosive ignition source is one of the most dangerous things I think of that you could do in a shop, which should be considered an enclosed space. It will cause a flash fire that spreads so fast you won't know how to react. Have you ever heard of the rock and roll star Roy Orbison? He was quite an active model builder and flyer along with his sons. His sons were killed in a house fire that started when they used dope and thinner too close to a heat source in their basement and it all erupted. Anyone with ANY kind of common sense WOULD NOT USE ANY KIND OF HEAT SOURCE NEAR HIGHLY FLAMMABLE SOLVENT TYPE MATERIALS!!! R%%%% R%%%% R%%%%

    Type at you later,
   Dan McEntee
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Offline Dennis Toth

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #8 on: October 08, 2017, 09:10:57 PM »
CharleM,
What you need a combination of the ideas presented, as Ty said let it gas-off for a few days and see how it starts to tightened. Next you may need additional coats before it seals completely and tightens. On my El Diablo I needed about 8 coats before the silk tightened.

Best,    DennisT

Offline wwwarbird

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #9 on: October 09, 2017, 08:16:37 PM »

 Another detail in the overall equation here is that any covering you use will only shrink so much, some more, some less, than others. You shouldn't really rely on the clear coats for achieving the desired "drum tight" shrinkage. You'll be best off working slowly from the start of application while getting the covering worked out and pulled as tight as possible everywhere during the process. If it's not pulled tight enough during the initial application you'll end up just chasing your tail (and adding additional weight) with more clear coats and it will never get "drum tight".
Narrowly averting disaster since 1964! 

Wayne Willey
Albert Lea, MN U.S.A.
IC Aircraft Modeler, Ex AMA member

Offline frank mccune

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #10 on: October 10, 2017, 06:56:39 AM »
       Hello Charles:

      I will bet you that the covering material had the grain running chord wise in lieu of span wise!  If this were the case, it will sag!!!! Ask me how I know! Dan was spot on with his reply.

      I recently made that mistake with some type silk/nylon blend. 

      The other that wwwarbird mentioned was not pulling it tightly when attaching the material to the frame.  This too will cause it not to shrink enough to look good.

                                                                                                 A silk and dope man,

                                                                                                 Frank McCune

Offline Allan Perret

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #11 on: October 11, 2017, 04:32:46 PM »
It is called Midwest Microlon.  It is an older synthetic silkspan.

Best Regards,
Charles Meeks HB~>
You have to understand whatever type of covering you are using.   Synthetic coverings are generally shrunk with heat, then only filled with dope.  That is the case with Polyspan.

If you doped Polyspan or other synthetis before heat shrinking it may never get tight. 

Now if you are using a paper based product [silkspan or the Dr.Paper] then you initially start the fill coats with tautening dope till you have desired tightness then switch to non-tautening dope to finish the filling process.  Paper based coverings applied damp will be tight from the gitgo and you will not need any tautening dope.  The whole doping process can be done with just non-tautening butyrate..
Allan Perret
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Slidell, Louisiana

Offline frank mccune

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #12 on: October 12, 2017, 07:42:22 AM »
      Hi All:

      Thanks for the information re. the Midwest Microlon.  I could not find the instructions for it but your post stimulated a few remaining neurons into opening that file and remembering that it was indeed Microlon.

      I must have picked it up at a swap meet circa 1980.  It was Kelly Green and worked very well by doping it on and applying a coat of dope. I applied it wet with water when doping it onto the frame.  However, one must apply with the grain running with the span.  I had no idea that one was required to heat shrink it prior to doping.  The results were very good when applied without heat shrinking.  As a mater of fact, I had covered a Combat Streak with it many years ago, and it was in perfect shape prior to crashing the plane.  It survived many Winter-Summer heat cycles in my attic prior to being terminated and looked as good as the day that it was built.  I would like to find a forgotten stash of it in my junk drawer!  I liked the stuff!

                                                                                                    Thanks for the information,
                     
                                                                                                    Frank McCune

 

Offline Allan Perret

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #13 on: October 12, 2017, 08:57:38 AM »
      Hi All:

      Thanks for the information re. the Midwest Microlon.  I could not find the instructions for it but your post stimulated a few remaining neurons into opening that file and remembering that it was indeed Microlon.

      I must have picked it up at a swap meet circa 1980.  It was Kelly Green and worked very well by doping it on and applying a coat of dope. I applied it wet with water when doping it onto the frame.  However, one must apply with the grain running with the span.  I had no idea that one was required to heat shrink it prior to doping.  The results were very good when applied without heat shrinking.  As a mater of fact, I had covered a Combat Streak with it many years ago, and it was in perfect shape prior to crashing the plane.  It survived many Winter-Summer heat cycles in my attic prior to being terminated and looked as good as the day that it was built.  I would like to find a forgotten stash of it in my junk drawer!  I liked the stuff!

                                                                                                    Thanks for the information,
                     
                                                                                                    Frank McCune
I have no experience with Microlon, never seen the stuff.  My advice was based on the OP saying it was a "synthetic" material.
Allan Perret
AMA 302406
Slidell, Louisiana

Offline Serge_Krauss

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #14 on: October 12, 2017, 09:44:24 AM »
Something to think about: dope that shrinks continues to do so for many years. I have a couple models where the dope has tightened silkspan to the point of tearing it open over open bays. I've seen this on some original classic stunters, one by Jim Kostecki that hangs on a friend's wall. I also have one small, "hollow-log" half-A plane where old dope shrinkage has pulled root fairings away from the fuselage over its half century. SO, if the dope is tautening and not sealing un-dried coats beneath the surface, just letting it set for a while should ultimately do the trick. Spraying thinner in a mist over the wing may help some gases escape from undercoats, if that's a problem.

SK

Offline Charles Meeks

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #15 on: October 12, 2017, 12:04:55 PM »
I know have 7 coats of 50/50 Brodak Butyrate dope on the wing and it is looking good.  After the replies here I waited 2 days and then put on a coat, waited a day and then another.  It has finally gotten "glossy" and is much tighter and more "solid".  I have been brushing on the dope, but I believe I will spray one or 2 more coats.  Thanks for every ones help.  I will get pictures posted as I can.
Best Regards,
Charles Meeks

Offline Dennis Saydak

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #16 on: October 12, 2017, 06:05:17 PM »
I've used Microlon very successfully in my R/C Days. It is a great product and it's as tough as nails compared to Silkspan. I still have an unopened package and here are the instructions for Microlon, in case you have more of it to use. Hope it shrinks out ok for you.

Just when you think you're getting ahead in the rat race.....you find the rats just get faster! MAAC 13120L

Offline Gerald Arana

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #17 on: October 12, 2017, 07:52:19 PM »
I've used Microlon very successfully in my R/C Days. It is a great product and it's as tough as nails compared to Silkspan. I still have an unopened package and here are the instructions for Microlon, in case you have more of it to use. Hope it shrinks out ok for you.


This sounds just like some stuff (Don't remember what it was) that I covered a wing with many years ago. When wet it expanse and when it dries it shrinks.

Well,  I had to rebuild the wing.....it crushed all the ribs! y1  Last time I'll ever use that crap!

Jerry

Offline wwwarbird

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #18 on: October 12, 2017, 09:20:59 PM »
I've used Microlon very successfully in my R/C Days. It is a great product and it's as tough as nails compared to Silkspan. I still have an unopened package and here are the instructions for Microlon, in case you have more of it to use. Hope it shrinks out ok for you.

 Interesting stuff.
Narrowly averting disaster since 1964! 

Wayne Willey
Albert Lea, MN U.S.A.
IC Aircraft Modeler, Ex AMA member

Offline Allan Perret

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Re: 5 coats of dope and covering is still not drum tight...
« Reply #19 on: October 16, 2017, 01:54:29 PM »
I've used Microlon very successfully in my R/C Days. It is a great product and it's as tough as nails compared to Silkspan. I still have an unopened package and here are the instructions for Microlon, in case you have more of it to use. Hope it shrinks out ok for you.
So these instructions indicate its not a synthetic material, and handles just like silkspan.
Allan Perret
AMA 302406
Slidell, Louisiana


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