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Problems with covering film...

sprzout

Knower of useless information
Mentor
#1
About 2 months ago, I was gifted an original Gentle Lady sailplane, from an estate that was donated to our club. Thing was in fairly nice condition, but I noticed that there were some splits in the covering over the vertical stabilizer, and what looked like some possible damage on one side of the elevator. I tried to take a better peek at the insides, and the stabilizer started moving around.

I decided I was going to just take the old orange covering that was originally applied, and upon doing so, discovered that the split was actually caused where the vertical stabilizer had broken (clean break, easily repairable, just a spot of glue to hold it together and fix it), and the damage to the elevator was a break from a crash that the previous owner had repaired, somewhat poorly.

I ended up stripping off all of the orange from the elevator and stabilizer, and trying to re-cover everything.

My father had bought a box of covering a while back at an RC swap meet - $25 for a box full of covering, and in it, there was a roll of stuff called Toughlon. It was relatively the same orange as what had been on the plane before; he offered the roll to me to cover the plane, with the best of intentions.

Well, as we know, the road to hell is paved with good intentions. Toughlon is a covering film with a VERY low adhesion temperature. Its range is anywhere from 136 degrees Fahrenheit to 250 degrees Fahrenheit. The irons I have range anywhere from 115 F to 450 F, and tended to run hot at the lower temps, reading at 140 F on the lowest setting. Because of this, it didn't want to stick properly at the lower temps. Upping the temp got it to stick, but as soon as I'd try to get it to shrink with a heat gun application or even the iron, it would peel up at the edges.

I went back to some of the older guys in my club who have been building and flying for many years, and they instantly told me, "Don't use that stuff. Most of it is old garbage. Try Ultracote."

A roll of Ultracote at the local hobby shop set me back $18, but it was WELL worth it. I was able to find almost the exact same color as the original orange, and the Ultracote had a much wider range for application and shrinking than the Toughlon stuff did. I was able to put the coating on with no problems, and it stayed stuck.

Lessons I learned:

1) Cheap/free isn't necessarily the best way to go.

2) Old covering is usually not a good thing to try to use. It might be worth it to spend the money and buy a new roll from the hobby store instead of trying to use someone else's rejects when it comes to consumables like covering, as there's probably a good reason why they didn't want it!

3) When in doubt, ask the guys who have been building this stuff for forever. Odds are they've learned techniques or have used the good stuff, so you don't have to slog through the garbage and suffer. Most are willing to help you! :)
 

Merv

Well-known member
#2
I have used quit a bit of covering but have never heard of Toughlon. Let's hope the rest of your dad's covering is better stuff.
 

sprzout

Knower of useless information
Mentor
#3
I have used quit a bit of covering but have never heard of Toughlon. Let's hope the rest of your dad's covering is better stuff.
Here's a link to the Toughlon:

http://airborne-models.com/html/Zproductdetails.asp?ProductID=80

The stuff I ended up using after the Toughlon failure was Hangar 9 Ultracote, which was far superior. :) I don't know what else my dad has in that box that he bought, but if the rest of it is like that, I'll be testing it before I try to put it on anything...Who knows, maybe I can iron it on to foamboard. Worth a shot; if it doesn't work or burns/melts the foamboard, I can just toss it and rebuild it.
 

Bricks

Well-known member
#5
What may help and I say may help do not try and shrink it until both sides are covered as " normally " most coatings will stick to itself better then to wood. Sealing the wood first before covering makes a huge difference in how the coating adheres.
 

Tench745

Well-known member
#7
I may be mistaken, but I seem to recall there being a product, either a sealer or a glue, you could paint onto the wood that would activate with heat and help stick covering. Not sure who made it or what it was called... maybe someone else will know.

Edit: Google has all the answers. https://sigmfg.com/products/sig-stix-it-covering-adhesive SIG Stix-it. Used for adhering silkspan and the like. Don't know if it can be used non-porous coverings.
 

sprzout

Knower of useless information
Mentor
#8
One thing i am certain of, all coverings have a shelf life, good stuff, cheap stuff, installed or not
That's what I'm figuring happened with this stuff. We have no idea how long this stuff was sitting around before we bought it; it was in a dusty box that probably came from the estate of (sadly) someone who passed on - that's what most of the balsa stuff seems to be from anymore, and covering is about the same.

As for the covering sealer/glue, I dunno if that would have helped. I have a feeling this coating might've started losing its adhesion due to the summers in inland San Diego; it was over 100 degrees for several weeks this summer, where my father lives. I wouldn't doubt this stuff was exposed to that heat. This stuff would stick until I applied a low heat to shrink it tight, and then BOOM, it pulled up. It wouldn't even stay stuck to itself, which makes me think it was just really lousy stuff or old, especially when I consider the Ultracote that bonded to the wood at about 150 F and stayed stuck when I came back over it with 250 F iron and heat gun to shrink it down tight. :)

@Bricks - You're right, NORMALLY it should stick to itself. The Toughlon didn't. So, either the adhesive was old, or this stuff just sucked from the factory; I don't know for sure. But, at least it's covered now with the Ultracote, and I KNOW it stuck. :)
 

The Hangar

Well-known member
#9
I have a gentle lady sailplane kit. It was given to me, and since I’m not familiar with balsa, I struggled to figure it all out, and finally put it away. I might try again sometime. Have fun with yours.
 

sprzout

Knower of useless information
Mentor
#10
I have a gentle lady sailplane kit. It was given to me, and since I’m not familiar with balsa, I struggled to figure it all out, and finally put it away. I might try again sometime. Have fun with yours.
If you can get it built, DO IT. The Gentle Lady looks like a great sailplane, and from what several members of my club have said, it's a very easy and forgiving sailplane to fly. If I wasn't afraid of it getting damaged in an 8 hour drive up to Northern California next week, I'd take it with me to do some sloping out by San Francisco. Instead, I think I'll take my Versa Wing, Nano Goblin, and maybe my F-27.
 

The Hangar

Well-known member
#11
If you can get it built, DO IT. The Gentle Lady looks like a great sailplane, and from what several members of my club have said, it's a very easy and forgiving sailplane to fly. If I wasn't afraid of it getting damaged in an 8 hour drive up to Northern California next week, I'd take it with me to do some sloping out by San Francisco. Instead, I think I'll take my Versa Wing, Nano Goblin, and maybe my F-27.
Next time I need a project, I’ll get it out and see what I can do. I don’t really have anywhere to slope soar nearby that I know of, but I can always build it as a motor glider!
 

sprzout

Knower of useless information
Mentor
#12
Next time I need a project, I’ll get it out and see what I can do. I don’t really have anywhere to slope soar nearby that I know of, but I can always build it as a motor glider!
You can certainly build it as a motor glider. As for a slope to try throwing it off of, if you don't have a hilly area (and it really doesn't take too much of a slope, but the steeper, the better) try looking around your area for a dam. There's been lots of guys who have successfully flown slopes out here that way. Check to see if it's ok to do that before you do it, though - otherwise, you might get a ticket for trespassing or worse.