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Author Topic: Sig Koverall Application  (Read 3715 times)

Offline Harold Brewer

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Sig Koverall Application
« on: June 18, 2019, 11:41:36 AM »
Has anyone had any experience applying Sig Koverall?  I opened up a package of it and saw heavy creases, which I am afraid, will cause issues when doping it down.  Since it has to be shrunk with heat, I can't use that method, which I have done successfully with silk.  Your comments appreciated.

Best regards,

Brew

Online gene poremba

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Re: Sig Koverall Application
« Reply #1 on: June 18, 2019, 01:38:28 PM »
 I use Sig Koverall a lot. I don't apply it with dope. I use Sig Stix-it applied to the outer edges of the wing. Once dry use a Monokote iron to iron down the edges just like plastic covering. Pull it tight to remove as much of the wrinkles as you can. Once the top and bottom of the wing is covered I use a heat gun and blow heat over the koverall to shrink it tight. You wont have any wrinkles in it, believe me. Be carefull not to create a twist in your wing. Try and shrink the top and bottom evenly. Finish is up to you from here on. I usually fill the weave with clear dope, prime,paint…..Gene

 PS, I have never applied it with out using heat to shrink it up tight.

Offline bob whitney

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Re: Sig Koverall Application
« Reply #2 on: June 20, 2019, 10:24:37 AM »
I use dope to apply koverall. I spray it with water like silk or tissue  it helps to take out the crease's
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Offline Steve Thompson

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Re: Sig Koverall Application
« Reply #3 on: June 20, 2019, 01:20:26 PM »
The method Gene added above works really well.  I think that is what SIG recommends also. 

I use SIG Nitrate over the Stix-it to anchor the fabric and then all Lite-Coat after.

I paint the tops and bottoms of the ribs with Nitrate prior to covering and let it dry.

After heat shrinking, where all the wrinkles do disappear, only then do I dope over the rib caps.

Very much like silk or tissue, except Nitrate is supposed to stick to the Coverall better and shrinking is done with heat rather than High shrink Super-Coat.

Cover-all is really strong.  Paint adhesion is why I understood to go with Nitrate.

Offline Dennis Toth

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Re: Sig Koverall Application
« Reply #4 on: October 23, 2022, 09:10:42 AM »
Once the Koverall is on how many coats of clear do you need to fill the wave and start appling color paint? Seems the Koverall although heavy (at 1 1/4oz/yd) will take a lot less dope to fill and should be about the same as 6mm silk just lots stronger and resistant to cracking.

Best,    DennisT

Offline john e. holliday

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Re: Sig Koverall Application
« Reply #5 on: October 23, 2022, 10:58:07 PM »
The number of coats depends on how thin you made the dope.   Usually I do 3 coats thinned 50% as it comes out of the SIG can.  Also I use 200 grit paper after the third coat only on the rough areas. D>K
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Offline MikeyPratt

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Re: Sig Koverall Application
« Reply #6 on: October 23, 2022, 11:00:09 PM »
Dennis,
All the above methods work well and are very east to apply.  The method I like best
Apply four coats of Supercoat dope thinned 50/50.  Lightly sand the wing to remove high spots and make it smooth.  Cut a piece of Koverall leaving at least 1” to pull on to remove any wrinkles. 

Starting on the bottom next to the fuselage, place a drop of thin CA glue, wipe off the excess CA glue with an clean cloth rag, then lightly stretching the Kuoverall the width of the wing next to the fuse, place another drop of CA glue and wipe off the excess as before.  Working your way down the length of the wing towards the tip, on the leading edge and trailing edge, place additional drops of CA about 1” apart and wipe off the excess CA.

At the wing tip, work slowly and stretch the Koverall and tack in place with drops of CA glue.  If needed apply heat to help the Koverall to conform to the wing tip shape.  Once you have the Koverall attached, apply more CA to the outside edges and wipe off the excess CA glue.  Make sure you cover the top and bottom of the wing before you attempt to shrink the Koverall.  This goes pretty fast using the thin CA glue.  Using this method only took and hour to cover the wing on a 78” Kadet Senior.

Shrink the Koverall with a heat iron on the medium to low setting.  Start on the boron and shrink only two rib bays on the bottom, then two bays on the top, alternating as you work towards the tip.  The coving should be tight and smooth, check for any works you may have and remove the warp by twisting and reheating the covering.

Once you have ithe wing coved you can apply the Supercoat dope to the covering (only one coat of Supercoat) dope and allow it to dry over night.  The next coats of dope will light coat dope thinned 50/50, when dry lightly sand with 400 wet or day sandpaper (dry).  At this point the Koverall look and feel pretty nice with the weave pretty well sealed.  If you want you can apply the color dope now, if you want fill the weave of the Koverall apply two more coats of light coat and lightly sand.

My old friend Claud MaCulough and I built two Sig Kobra’s that were finished, one covered in silk and one with Koverall, the same amount of dope and paint, in the end both were the same weight when finished, no engine or or R/C gear were installed yet because they were going use different engines.

One other note, I built a Veco Chief (pollywog) for the Nat’s and VSC, it also was covered with Koverall that was awarded the Spirt of 52 at the Nat’s and the high point Finish for OTS at VSC.

Mikey Pratt
« Last Edit: November 04, 2022, 08:15:38 PM by MikeyPratt »

Offline Dennis Toth

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Re: Sig Koverall Application
« Reply #7 on: October 24, 2022, 06:56:35 AM »
Thanks Mike,
I have used the CA pin method on silk and glad to hear it works with the Koverall. This method allows covering inside when its to cold or hot or humid to do the traditional dope application.

Since Koverall is some type of man-made fiber i don't think it absorbs dope like silk or silkspan, being more like polyspan. How many coats of clear to fill the weave smooth (for a clear finish) or go to primer?

On silk or silkspan I usually need 8 to shrink than 4 more to seal to a smooth surface (clear finish).

Best,     DennisT


Offline MikeyPratt

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Re: Sig Koverall Application
« Reply #8 on: October 24, 2022, 06:55:08 PM »
Hi Dennis,
I liked the look of the weave so I always stopped at four coats, two more should fill it, sanding sealer will also fill it if you want, it’s mostly clear with talc added so it’s not as heavy as auto primer.  Also remember that you can spray clear after the color on it to fill the weave even more.

Later,
Mikey

Offline Dennis Toth

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Re: Sig Koverall Application
« Reply #9 on: November 04, 2022, 08:21:51 AM »
Mike,
What are you using for a block coat - primer (color?) or base paint?

Best,    DennisT

Offline MikeyPratt

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Re: Sig Koverall Application
« Reply #10 on: November 04, 2022, 08:11:47 PM »
Dennis,
For Dope, depending on the base color, I’ve used clear, or sanding sealer with Sig White added to the sanding sealer about 4 ounces per pint.  After sanding off most of the sanding sealer the model is still mostly white.  Now you can paint the base color white.  Yellow, red, light Blue, and sometimes silver need a even coat of white under it  Then the base color will layout very even and smooth.  You could also use gray if you wanted, but my require more coats for an even trim color.

Later,
Mikey

Offline Dennis Toth

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Re: Sig Koverall Application
« Reply #11 on: November 05, 2022, 07:19:34 PM »
Mike and others,
One other question that I think many might find interesting, At what point do you switch from brush coats to spray? Do you brush the filler coats (OK two questions)?

Best,    DennisT

Offline MikeyPratt

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Re: Sig Koverall Application
« Reply #12 on: January 24, 2023, 11:06:33 PM »
Sorry Dennis,
I just saw this, you can switch to spray after the weave is filled (3 or 4 coats).  I always used 5 coats of thinned 50/50 of Sig light coat dope then spray sanding sealer with 4 ounces of white added, then thin 50/50, spray 2 coats and wet sanded with wet 400, then a sealer coat of clear then switch to color.  That’s what I used on my Veco Chief and Yates Dragon for Old Time, they looked really cool with only a light showing of the weave after it was cleared with dope.  It was shinny and didn’t need rubbing out.  FYI, I use the same method on poly span.

Mikey


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