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Koverall Repair Question.

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Old 09-23-2012, 09:52 AM
  #1
FlyCubs
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Default Koverall Repair Question.

After several fun flights of my Sig 1/4 scale Cub, I had a case of dumb thumbs which resulted in a spectacular cartwheel. The guy who built the Cub was very good at what he did. He covered it with Sig Koverall and finished it with an acrylic latex. It's a tough bird and the extent of damage was limited to the top of the rudder being bent over a few degrees and some wrinkles in the covering where it's bent. I have been able to remove the rudder by heating it a little at the hinge points and then pulling just enough to pull the hinges out intact. Then I used an exacto knife to remove the covering on one side (the side with most wrinkles) so that glueing the wood spars would be possible. So, now I have the rudder basically fixed - it's nice and straight and stronger than before. The problem I need help with is how to patch the covering. I have plenty of Koverall, some nitrate dope, butyrate dope and even some leftover acrylic latex paint.

The first question is how to prepare the rudder so the Koverall patch will stick to it. There are places on the repair (eg. on the spars) that are painted with acrylic latex where I need to make the Koverall stick. I think if I use either of the dopes, it will have bad effects on the latex. I have tried coating a scrap piece of balsa with Titebond II wood glue and ironing the Koverall to it after it dries. It sticks a little but the bond is not anywhere close to how strong it needs to be. I have read where people have used water based contact cement. Would like some opinions on that if anyone has experience or suggestions on any other methods that could work.

The second question us how to finish the Koverall after I get it stuck good to the rudder. Will the acrylic latex alone fill the weave enough or do I need to use a primer? Whatever I use must be compatible with the acrylic latex already on the rudder.

Thanks for any and all suggestions. I miss flying the Cub and am anxious to get it back in the air.

Steve

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Old 09-24-2012, 08:25 AM
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tallone66
 
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Default RE: Koverall Repair Question.


 In my experiance, you will have to remove the paint back from the repair site so you have room to feather the patch in. Minwax poly C can be used in place of the dope, same method, paint area with polyc, let dry, lay Koverall on area, paint polyc on area with base coat and let dry completly, then shrink.
 Filling the weave is very quick with the polyc, it sands quite well when good and dry. I would primer with latex primer, sand, then color coat.
If patient, you should be able to blent the repair so it can not be seen. Nice thing about polyc is it is latex, no odor and cleans up with water.

Cheers
Derrick
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Old 09-24-2012, 04:38 PM
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Default RE: Koverall Repair Question.

Thanks for your reply Derrick. When you say "remove the paint back from the repair site" do you mean to sand the paint off the areas of overlap so that the fabric is showing? About 70% of the overlap area is on the edge of the rudder so it won't be too bad. The remaining 30% is on a spar as you can see in the photo in my post above. I will get some Poly C and experiment with it a bit before applying to the rudder. I am new to Koverall but love the finish it gives. Would like to learn more about it because I am turning the corner from 3D to scale airplanes which would look great with this finish.

Steve
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Old 09-25-2012, 09:45 AM
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Default RE: Koverall Repair Question.

Lots of information in RCU on all covering and finishing techniques a search using "covering and finishing" brought up a bunch, two of which are:

RE: Sig Koverall Application Process
[quote]ORIGINAL: LargeScale88 Hi everyone. I'm just finishing an airplane up and I've decided to cover it with Sig Koverall and nitrate dope. Having not used this covering for several years..., both for prepping the structure and on top of the covering. The comment about connecting to the ribs... a more positive bond. In general, I keep in mind that this product has no adhesive on the covering, I need
Posted on: 8/5/2012 9:40 AM by Author "RCVFR" in the forum "Questions and Answers"
http://www.rcuniverse.com/forum/fb.asp?m=11181635

Sig Koverall Application Process
Hi everyone. I'm just finishing an airplane up and I've decided to cover it with Sig Koverall and nitrate dope. Having not used this covering for several years, I'm a litte rusty on the process, so I just wanted to clarify the standard process for putting this stuff on properly. Ok, heres what I can remember: 1. Apply 2 coats of unthinned nitrate dope to framework (except ribs
Posted on: 8/5/2012 7:51 AM by Author "LargeScale88" in the forum "Questions and Answers"
http://www.rcuniverse.com/forum/fb.asp?m=11181552...

Good luck.

Sincerely, Richard/Club Saito #635
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Old 09-25-2012, 05:48 PM
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Default RE: Koverall Repair Question.

If this were my airplane I'd find it easier to just remove all the covering on the rudder and then put on new. So long as you know the paint codes a match will be easier. Paint 'weathers' and it would be hard to match it up as a patch job. Get some Stix-It and apply the Koverall to the framework. If you can't contact the builder then don't use nitrate dope. If butyrate is on the framework then nitrate won't work over it.
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Old 09-26-2012, 04:45 PM
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Default RE: Koverall Repair Question.

I don't want to hijack the Thread but wanted to ask one question... If I covered an open-bay wing with this, would I be able to paint it with Klass Kote? And what might the results be?

Thanks,

Bob
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Old 09-26-2012, 06:25 PM
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Default RE: Koverall Repair Question.

Hello Bob,

The answer is yes. The last plane that I built using Koverall was a Flair Fokker D. VII. First a coat of Blasarite was brushed on the airframe. Sig Stix-it also works well. Next you iron on the Koverall. Using the wing for an example, you iron on the Koverall fabric around the edges of the wing, where the Balsarite was brushed on in the previous step. After that pass your Monokote heat gun over the wing to shrink the covering tight but not to tight. You don't want to warp your wing. Next I brushed on three coats of Sig Nitrate Dope to help fill the weave of the fabric followed by the epoxy paint sprayed on with an automotive touch up gun.

I have done many planes this way with great results every time. Here are a few pictures of airplanes that where done with Koverall, Nitrate dope, and epoxy paint.





Ripley
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Old 09-28-2012, 04:08 PM
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Default RE: Koverall Repair Question.

Thanks for answer, Bob

Bob
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