Sig Low Shrink Lite Cote issues

[Shorts,David]

Hi, I covered my airplane in silk and it was nice and tight over the wing bays. I am using Sig lite cote butyrate low shrink clear. I'm wondering if that was a big mistake. I have put two coats of clear over  the wing bays and now they are saggy. First cote was thinned about 65 thinner, second cote closer to 50/50.
Should I continue and it will shrink up around cote three or four?
Could I switch to brodak butyrate clear?
Should I strip the wings off and switch to brodak clear?
Should I go back to monocote and save weeks of my life?

[Shorts,David]

That is much better than tear the covering off and start over. I'll give it a shot, and see what opinions follow since I have to order regular clear anyhow.

Follow up question. When I've done all my detailing and I want to put some clear on top, should I use the lite cote at that point?

[Avaiojet]

David,

As said, thinned dope on open bays can do the trick.

I have no patents so I speed dry my dope using a heat gun holding it at a considerable distance. Lid the can and try not to burn the house down.

Currently, I use dope only on the framed model, 3 coats or so. Open bay wings, I apply silk dry silk using CA. Sheeted areas like the fuselage, tail feathers, I've used Minwax Polycrylic and Deft Wood Sealer. I believe this stuff is as good as dope, possible better for applying silk to sheeted areas. There are others who use these two products also.

FYI and for what it's worth, FWIW, as I said, I now apply silk dry using CA. I've done this on three models with excellent results. Really excellent results.

But don't take my word on it, you can go over to CFC Graphics vendor's corner and see the finished product photos at the:

Gee Bee R-3 build.

I have other builds scattered about where I mention using CA to apply silk dry.
You would have to find the Gee Bee Z build and the ARGO 2 build. Both these models came out perfect, as they should.

Next model, if you are considering trying my technique, please contact me because, like all good things, there's stuff you have to know. Do not attempt this without a conversation.

There is another modeler in this Forum using my method. Maybe he'll chime in?

[944_Jim]

Be very patient at this point. My 1/2A Mosquito did the same thing. So I laid into it with Sig Super-Coat to snug it up. All looked fine after a few coats and a hairdryer.

So I set the model to the side, feeling absolutely smug about the ordeal.
When I came back the next day, I had a Pringles chip!

One coat over open bays...at least two days to let the coats work together. Do both sides of a structure so the tissue pulls evenly without warping the structure. Then check a couple days later. You may want to put the model in the warmest room of the house. I seem to remember reading putting the model in a car to bake it. If I chose that route, I'd be watching throughout the day frequently. Oh, did I mention wait a few days between coats?

[ericrule]

Yep, Lite Coat has an additive that that reduces the shrinkage. Never use it on silk or anything that you want to stay shrunk. If you use Sig clear always go with the Super Coat which does not have the additive.

[Dan McEntee]

   There is a right way and a wrong way to do everything, and the archives of this forum are filled with horror stories of guys trying to take short cuts and hurry things along and the problems that this causes. The old SIG catalogs had a section on the proper ways to work with dope, what their products were and how to use them. I think these same pages are on their website now also. The methods still work and the products are still the same. It explains what the tautening products are and why you use them and when. All of SIG's color dope is blended with Lite Coat as a base, so you just need to make sure you have things where you want them before you start putting on color. When you add color, things may sag just a bit, depending on how heavy handed you are with the gun, but will shrink back up, and the important thing is that it won't get like Aerogloss and keep shrinking and split the covering.All of this is here on the forums and have been "covered" (pun intended!) before. Search out threads by Bill Byles or Jim Thomserson and you will get the straight "dope" (pun intended again) on correct procedures.  The Windy tapes on finishing are an excellent source also.
  Type at you later,
  Dan McEntee

[Balsa Butcher]

Many good ideas presented here. In my experience neither polyspan or the (ugh) new silkspan tighten up as tight as the old silkspan however over time they will continue shrink. Silk is an art unto itself and I can't say if the new has the same shrinking qualities as the old. At any rate, to get these new coverings to shrink a bit quicker I spray on a couple of coats of Sig "Supercoat" clear (which is tautening)  before continuing my finish with Lite Coat. This may work for your project.
If it hasn't been mentioned, Sig colors are labeled "Supercoat" but are in fact lite-coat based. For great on dope look up any of Bill Byles posts on the subject. If you still live in Sacramento look me up, I can show you many flying examples of what has worked for me and what hasn't.   

[Shorts,David]

Thanks guys!

I actually was given a gallon of lite cote and didn't know there was a supercote until this happened and I looked up some of the other threads. I ordered some supercote this weekend and sometime next week will put it on the open bays.

Pete, I was hoping to have it by meet n meat, but now maybe I'll have it by golden state...or there's always next year.

[Dennis Saydak]

I have two models in clear coat right now that have several coats of SIG lite coat over two initial coats of nitrate clear. The covering shrunk up nicely after the nitrate coats, which I left untouched for about a week before using the Sig clear. Just as you experienced the covering went saggy on me and I was initially concerned. However, after a few days the covering shrunk right back up very nicely. So the problem you encountered is not unusual and should be temporary.

[MikeyPratt]

Come on guys this is not rocket science, it’s just dope.  There are a number things on here that are right and others not so right.  Use lite coat clear to attach silkspan, plyspan, polyspan, silk, or what ever. Apply two thinned coats of Supercoat thinned 50/50 to the open bays and allow to dry overnight.  Lightly sand with 320 and clean off the dust, then apply two coats of (low shrink) Litecoat dope.  The covering will sag slightly then shrink back up over night.  If your not happey with the coverage then add a third or forth coat of Litecoat and lightly sand with 400 grit sandpaper to knock off any fuzz. 

Then go to your primer (sanding sealer, talcum) add two coats and allow to dry for a week, sand the primer with 600 grit paper and clean of the entire model with Windex Glass cleaner (twice until it’s squeaky clean).  From this point on spray your base color two coats and allow to dray at least a day or two, again sand with 600 grit paper then follow that sanding up with 1000 grit paper and clean the model With Windex again.  Add you trim colors and other trim.  Use a credit card to rub over the edges of the trim to knock off and paint edges from the tape.  Clean the model again with Windex and paper towels.  Spray a coat of Litecoat over the model concentrating on the edges of the colored trim at first the the entire model after that.

At this point it should be looking great but it’s not done yet lol.  After the dope has cured a few days you can lightly sand with finer sandpaper like 1500 grit to get a dull even finish.  You can add you ink lines, transfers, and any additional trim you may want, when finished spray a sealing coat of Litecoat dope on the entire model.  After the sealing coat you can spray on you one/two coats of your automotive clear.

Of course you can make exceptions to the above if you want a different outcome or look.  By adding a small amount of colored dope to the clear you can get a transparent look to the covering (yellow, red, blue, green etc).  Myself I don’t use the poly paint, dope still works better and I know how to use it.  Other things I’ve learned about painting with dope is keep your work area clean and wash you hands every time you are touching you model especially after eating buttered popcorn, Tacos, or any grease food that can be transferred to your model, don’t laugh many modelers called and said the dope is not drying or blistering, go figure what they had for dinner or lunch lol.

Mikey

[Alan Resinger]

One thing I will add to Mike's post is to spray two lite coats of lite cote on your base color if the color is white or something with a light hue.  This will make clean-up from overspray or tape leaks much easier.

[Dan McEntee]

Come on guys this is not rocket science, it’s just dope.  There are a number things on here that are right and others not so right.  Use lite coat clear to attach silkspan, plyspan, polyspan, silk, or what ever. Apply two thinned coats of Supercoat thinned 50/50 to the open bays and allow to dry overnight.  Lightly sand with 320 and clean off the dust, then apply two coats of (low shrink) Litecoat dope.  The covering will sag slightly then shrink back up over night.  If your not happey with the coverage then add a third or forth coat of Litecoat and lightly sand with 400 grit sandpaper to knock off any fuzz. 

Then go to your primer (sanding sealer, talcum) add two coats and allow to dry for a week, sand the primer with 600 grit paper and clean of the entire model with Windex Glass cleaner (twice until it’s squeaky clean).  From this point on spray your base color two coats and allow to dray at least a day or two, again sand with 600 grit paper then follow that sanding up with 1000 grit paper and clean the model With Windex again.  Add you trim colors and other trim.  Use a credit card to rub over the edges of the trim to knock off and paint edges from the tape.  Clean the model again with Windex and paper towels.  Spray a coat of Litecoat over the model concentrating on the edges of the colored trim at first the the entire model after that.

At this point it should be looking great but it’s not done yet lol.  After the dope has cured a few days you can lightly sand with finer sandpaper like 1500 grit to get a dull even finish.  You can add you ink lines, transfers, and any additional trim you may want, when finished spray a sealing coat of Litecoat dope on the entire model.  After the sealing coat you can spray on you one/two coats of your automotive clear.

Of course you can make exceptions to the above if you want a different outcome or look.  By adding a small amount of colored dope to the clear you can get a transparent look to the covering (yellow, red, blue, green etc).  Myself I don’t use the poly paint, dope still works better and I know how to use it.  Other things I’ve learned about painting with dope is keep your work area clean and wash you hands every time you are touching you model especially after eating buttered popcorn, Tacos, or any grease food that can be transferred to your model, don’t laugh many modelers called and said the dope is not drying or blistering, go figure what they had for dinner or lunch lol.

Mikey

    Hey Mike!!!
     That is pretty much what was covered in that section in the old SIG catalogs, correct? All except the part about buttered popcorn, tacos and such! No need to cover that because they had not built the new Hucks in Montezuma at that time! Good to see you posting and we GOTTA get together an fly somehow next year! I still need to get a flight or two on Gretz's Fierce Arrow yet this year.
    Type at you later,
     Dan McEntee