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Author Topic: slc covering  (Read 8552 times)

Offline jjorgensen

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slc covering
« on: December 26, 2010, 02:05:40 PM »
what kind of surface prep do you need with this product? Can it be applied directly over bare balsa? Does it have adhesive already? What is the thickness?
Jim Jorgensen

Offline Bill Little

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Re: slc covering
« Reply #1 on: December 26, 2010, 03:02:38 PM »
what kind of surface prep do you need with this product? Can it be applied directly over bare balsa? Does it have adhesive already? What is the thickness?

Hi JIm,

I am waiting to get some.  I understand it has its own adhesive and will go over bare balsa and basically anything else.  it's very thin, but almost puncture proof.  I plan to put silkspan over it, which you can do with dope.
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Offline jjorgensen

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Re: slc covering
« Reply #2 on: December 26, 2010, 04:33:49 PM »
Thanks for the reply. I think I'm going to give it a try. I read on one of the RC forums that you could also put silk span over it with minwax poly, and it does away with the problem of using minwax over open bays. If so, that will help a lot working in the house without smelling it up so bad with dope!
Jim Jorgensen

Offline Bill Little

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Re: slc covering
« Reply #3 on: December 26, 2010, 04:40:07 PM »
Thanks for the reply. I think I'm going to give it a try. I read on one of the RC forums that you could also put silk span over it with minwax poly, and it does away with the problem of using minwax over open bays. If so, that will help a lot working in the house without smelling it up so bad with dope!

I'm pretty sure I have read that one of the Moon Brothers or Brad Walker used water based poly to attach the silkspan over their SLC.  I believe Doug and Brad are members here, so a PM to Doug or Brad would probably answer a lot of questions and give you some tips.
Big Bear <><

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James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Offline phil c

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Re: slc covering
« Reply #4 on: January 19, 2011, 07:09:54 PM »
A little more background on SLC covering:
It is polyester,  .75 mil(.00075 in.)  very light, over 20,000 sq.in./lb
It is fairly tear resistant, unlike some other films(polypropylene esp.) so a tear doesn't usually run away.
It has a fuel resistant adhesive on one side.  It can be lifted up and repositioned at least twice, if needed.
Low temp, goes directly over foam.  I use about 275 deg. on a Coverite iron.  I can pretty easily form it around rounded off bare foam tips with no wrinkles(takes some practice, but is pretty easy even with just an iron)
The film is treated for paint adhesion.  This treatment does have a shelf life, but for film that is rolled up it should be pretty much indefinite.  Most people lightly buff the surface with green Scotchbright.

Make sure the film goes on without wrinkles on the flat surfaces.  Any wrinkle is impossible to get out.  Wrinkles around the tips and edges can be covered with silkspan and filler and sanded to cover up.  But the stuff is incredibly stretchable, so it will go around most curves.  Move the iron around and work it in stages so an already smooth area isn't reheated and pulled into a wrinkle.

Apply one coat of auto primer.  You can use almost any kind.  Rust-O-Leum Auto Primer is cheap and easy to apply.  One thick coat, and then sand almost all of it off.  If the edges are properly ironed down(by wiping the iron across the edge) one coat of primer will completey hide any seams.

Any other paint can go over the primer.  Auto two part, Rust-O-Leum, even dope.  Doug Moon has done several planes with auto paint and had excellent results.

You can apply silkspan or silk over SLC.  Water-based polyurethane varnishes(Carver-Tripp, Varathane are fuel proof versions) or Min-Wax(not fuel proof).  Dampen the silkspan lay it in place and work the varnish through it.  Make sure all wrinkles are worked out as much as possible.  A wrinkle in the middle of a panel will be VERY difficult to sand out.  Wrinkles in the silkspan around the tips can be sanded and filled to make them disappear completely.

On a large stunter (700+ sq.in.) adds about two ounces for a layer of covering.  One solid coat of paint adds the same.  A complete finish, SLC, primer, base color, trim, will run 6-8 oz. no matter what paint is used.  Adding a layer of silkspan adds another couiple of ounces.
phil Cartier

Offline Kim Mortimore

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Re: slc covering
« Reply #5 on: January 20, 2011, 06:51:31 PM »

Phil,

Can Rustoleum paint (not primer) or water-based polyurethane be used on SLC over open bays without cracking?

Thanks.
Kim Mortimore
Santa Clara, CA

Offline phil c

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Re: slc covering
« Reply #6 on: February 04, 2011, 07:28:37 PM »
I haven't actually tried Rust-O-Leum on the plain covering over open bays, so I cannot speak from experience.  However, putting the film over foam doesn't give a very stable surface, but the paint holds just fine.  The Russians have been using fim under silkspan or silk since sometime in the 70's.  It works well.

I did have a friend(Gil Reedy) who put the film on an openwork plane(Sterling Mustang) and painted it with Rust-O-Leum.  He complained that after a straight in crash the paint broke loose from the film.  That is why a lite buffing with Scotchbright(tm) and primer is a good idea.
phil Cartier

Offline Martin Quartim

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Re: slc covering
« Reply #7 on: March 13, 2011, 10:35:00 PM »
Hi Phil,

I am building  Dave´s Thunder Gaser and I planing to cover the wing with SLC film. I have a few questions though.

1. Can carbon veil be applied over SLC film with dope? Would that help make a stronger wing then using Silkspan?

2. Should I cover just the open bay areas with 1/2 over  and then cover the whole wing with silkspan/cabon veil, or should I cover the whole wing with SLC and then apply the Silkspan/Carbon Veil?

3. What is the advantage compared to a PolySpan covered wing, if any ?

Thank you,

Martin
Old Enya's never die, they just run stronger!

https://www.youtube.com/user/martinSOLO

Offline Bill Little

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Re: slc covering
« Reply #8 on: March 13, 2011, 11:32:22 PM »
Hi Martin,

I am going to be applying the SLC to a 58" open bay stunt wing tomorrow.  I plan to only cover about 1" (give or take) around the open bays, then cover everything with the silkspan.  And I am going to attach the silkspan to the SLC with nitrate dope.

I don't think I will cover the entire "covered with SLC" wing with CF.  My wing is already in the fuselage, and the CF would not be able to overlap the center section.  The reason I am concerned with that is a memory of Bob Gieseke covered his wings with CF and one folded at the fuselage.  IIRC, he said it was due to a stress riser being created there with the extra stiffness produced from the CF covering stopping there.  Someone will correct me if that is wrong, but I think I have it pretty correct.  Anyway, I don't believe that for our purposes the CF would be needed over the SLC.  Silk or silkspan over the SLC should provide plenty of strength, all things considered.  Especially since the wings can simply be covered with SLC alone and nothing over it like is done with the combat ships.  Those wings sure seem to have a lot less structure yet hold up to a great deal more stress.  A square corner at ~60mph with our stunt ships versus one at 100mph on those combat jobs....... ;D

Big Bear
Big Bear <><

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James Hylton Motorsports/NASCAR/ARCA

AMA 95351 (got one of my old numbers back! ;D )

Trying to get by

Offline phil c

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Re: slc covering
« Reply #9 on: March 17, 2011, 07:59:48 PM »
Martin, I'd cover the whole plane.  The film gives a very smooth, uniform surface for further finishing.  If the carbon veil isn't really stiff it will stick down fine and probably stiffen the wing some.  Actually, using a very thin coat of epoxy finishing resin would add more stiffness.  The stiffness of a composite comes from the combination of very stiff fibers packed solidly in a strong matrix, usually they try for 50:50 carbon:epoxy if you can get it.  Usually this takes molding in a high pressure mold.  Dope and silkspan provides very little increased stiffness. 
phil Cartier

Offline john e. holliday

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Re: slc covering
« Reply #10 on: March 21, 2011, 10:13:32 PM »
I covered a plane entirely with the SLC.   Then buffed with the Scotchbrite pad.   Put the silkspan on wet with thinned dope.  It was only doped around the edges.   Once dry, it was amazing how well the silkspan shrunk.  Took less dope to fill the silkspan.    Of course I didn't sand until I had about four coats of thinned dope over everything.   Then it was a very light sanding.   The SLC makes for as smooth surface as it is put over.  As with any thing it takes patience and practice to get it right.    H^^
John E. "DOC" Holliday
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Offline Martin Quartim

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Re: slc covering
« Reply #11 on: March 23, 2011, 09:12:18 AM »
thanx for the help Bill, Phil and John.

Martin
Old Enya's never die, they just run stronger!

https://www.youtube.com/user/martinSOLO


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