iflyg450

I just got into 1/2a control line flying. If you have never tried it, I highly recomend giving it a go! I am building one now, and I want to do it in silkspan. My question is which dope is best Brodak or Sig. I have heard good things about brodak but they didn't know how much nitro it could take. I run 35% sig in all my cox and norvel engines. What other paints process can be used with silkspan???

rainedave

My Feedback: (1)

35% nitro will dissolve Brodak clear butyrate. 25% will not harm it. I know this for a fact, at least when using Sig Champion fuels.

I prefer Brodak dope to Sig. Brodak dope is actually Randolph dope.

The thinner you use is probably the most important choice you'll make with dope. Try to find Dupont 3608S. If you can't - it was difficult for me to track down - then use Randolph or Brodak thinner. You can buy larger quantities of Randolph from Aircraft Spruce and save a few bucks:

http://www.aircraftspruce.com/

David

iflyg450

Good to know, I think I will drop my nitro content down to 25% I am sure that the 35% is getting me that much more over what the 25% does. I was thinking of turning your sure shark into a control line model.

skaliwag

My Feedback: (1)

I have not used it but been told Nelson paint is high nitro proof.

http://www.nelsonhobby.com/paint.html

eroc144

My Feedback: (1)

Dope-wise, my preference is Brodak. Nelson's paint can be made fuel-proof by using Nelson's crosslinker product.

I've used Brodak's dope and Nelson' paints on a lot of planes over the past few years and am slowly migrating to Nelson's - it uses water as a thinner and is less "nasty" than dope. Plus I like the fact that I have an unlimited supply of thinner via the kitchen sink. But I admit I miss the smell of dope in the morning...

Unless you have a significant investment in dope / thinner, I'd take a good look at Nelson's.

EG

iflyg450

Thats what I have heard as well, its a bit pricey 13.00 for a 1/2PINT. Its starting to look like I can lower my nitro use or cover with plastic film

Andrew

Unless you're looking for all out speed, there's likely not a lot of gain in moving from 25% to 35%. The old NORVEL FAQ site did not recommend 35% except for competition.

I've used Aircraft Spruce (the site rainedave recommended) for a number of products including dope. You can get tautening and non-tautening nitrate and butyrate clear, plus colors. If you buy in quarts only, there is no Hazmat surcharge.

Besides, where else can you have so much fun using dope and alcohol and still be legal?

andrew

iflyg450

eroc144

Do I still use dope to attach the silkspan? I guess the nelson paints fill the weave of the fabric?

eroc144

My Feedback: (1)

When you factor in the cost of dope thinner Nelson's becomes much more cost effective. Dope thinner is roughly the same cost as the dope, so you need to double the base cost for starters. For brushing you're thinning the dope at least 1:1 with thinner, and if you're spraying you have to thin even more, then you have cleanup and.... the list goes on.

Admittedly, dope is the favorite "glue" for silkspan but you can also use thinned white glue. I've been using water-based polyurethane on koverall & fiberglass with good effect, and that might work on silkspan as well. I'm sure lots of guys here will chime in with other non-dope silkspan attachment methods.

Let me know if you decide to go the dope route - I've got a dozen pints that might be looking for a new home. Of course we'd have to figure out how to ship them...

EG

Andrew

EDIT: Whoops - EG posted while I was typing.

In the "olden" days when the only choices were silk, tissue or silkspan, the basic technique was to dope the open structure with full strength nitrate several times, sanding in between. After 3 to 4 coats or until the grain was no longer raised, the silk or silkspan was applied wet (soaked, then squeezed out), doping the edges with a 50/50 nitrate/thinner mix - many times I've used my fingers to rub the dope into the covering to ensure that it penetrated to the underlying wood. Cellulose dope has the characteristic that it will re-dissolve with thinner, so additional coats stick to the underlying coats very well. Nitrate has a slightly higher adhesion property than butyrate, consequently it was preferred for "sticking" down the covering. Tissue is applied dry, then spritzed with water or alcohol to shrink. When using a wet covering, the edges will blush or turn whitish; this will normally disappear with the next coat. If you needed to reposition a small part for any reason, the dope would release with pure thinner and you could repositon and stick down again.

The open areas were doped with tautening nitrate; solid areas were doped with non-tautening nitrate. If you doped balsa fuselage sides with tautening dope, it could add quite a curl - I ruined a fuselage doing that. Nitrate is not fuel proof or even fuel resistant, so it must be covered with butyrate. You cannot use nitrate over butyrate.

I have generally covered exclusively with butyrate - in our applications, it sticks well enough and we don't fly at speeds high enough to pull the covering loose. For brushing, I usually thinned 50/50; for spraying, it may need to be thinned even more. Early dope was available as tautening only and needed a "plastizer" added to keep it from shrinking too much. Castor oil was the poor man's additive. Today, it is commercially available as non-tautening.

I would usually cover with about 1/2" extra around the edges. After 2 or 3 coats of dope, the extra covering would be stiff and could be cut away with fine sandpaper on a block. What few fibers remained would dope down on the next application. If you poke a hole in the silkspan or tissue covering, tear a patch out, don't cut it. Tearing leaves a fibrous edge that feathers in without showing much. Tissue is pretty fragile and you can save considerable weight by using colored tissue doped only with clear. Silkspan is available in 3 weights - the lightest will work for most of our models.

Many folks don't like the smell of dope or the associated thinners - I always thought it smelled like fun.

andrew

mikegordon10

And all this time I thought the smell was the main reason I used it! Go figure!

iflyg450

It sounds like Nelson paints are the way to go. Any other ways of attaching silkspan to the plane? I like the thinned white glue idea. The nelson paints do they fill the weave of the silkspan?

eroc144

My Feedback: (1)

Nelson's is pretty thin and does not fill very much, but if you're using the lightest silkspan / tissue there should not be much weave to fill.

Another option is latex paint with a topcoat of Nelson's clearcoat & crosslinker to make it nitro proof. Yup, I mean like Behr paint @ home depot - there's lots of info on this method @ the Warbird forum. Pretty much any color you want & at reasonable prices. I haven't tried it yet but it's on the list. Not sure how it comes in weight-wise.

EG

iflyg450

which weight of K&S Silkspan should I use "00" "000" "SGM" ? The plane is a Norvel 061 control line model.

xpebrian

am getting ready to assemble guillows corsair f4u-4 model and was wandering on what type of dope you use to cover the silk-pan that came the kit was goining for an authentic look with the dope how do i add the color or do i use colored dope what do you recommend nitrile or butrate dope witch is better and easiest to use and where is a good place to get product and what is a good technique for this i am new to this hobby have help for plain but need info on how to cover



thanks in advance for all the help

MJD

My Feedback: (1)

First step: Google "how to cover an airplane with tissue" and see what pops up. There are how-to's all over the 'net.

Materials:

[link=http://www.brodak.com/shop_search.php?productsearch=dope]Brodak

[/link][link=http://www.sigmfg.com]SIG[/link]

.. just a couple of starters for you.

Is this a display model, or do you plan for it to fly?

MJD

xpebrian

i was thinking of making it a flying model


thanks alot

MJD

My Feedback: (1)

Then lay real low on the color dope. Try to find color tissue and clear finish that if possible. But the level of finish is, in the end, up to you - a personal balance between looks and flyability. The better you get at building the less compromise you have to make I guess.

MJD

Yuu

OO is the thin stuff. GM [gas model] is heavier... SGM [super gas model] is the heaviest.

Jim Thomerson

I have painted silkspan with very thinned down white glue. This gives fairly good filling and is sandable. I've only used dope over it, but any of the other paints mentioned should work as well. For sanding open bays, I use steel wool. Less likely to cut at the ribs, but run a magnet over it after you are finished.

SnApRoLl-

When I cover airplanes with tissue paper, I apply thinned down Elmer's white glue on the airframe for gluing the tissue down, then after I apply the covering, I wet the tissue with a spray bottle full of water and I carefully dry it using a blow dryer to shrink it. And for painting, I have used Top Flight's Luster Kote paints with great success when I couldn't find any Dope at my LHS.

Yuu

I've read on the FF sites that a product called "Future" floor cleaner/sealer works for silkspan and nylon, but haven't tried it. Don't know about 'fuelproof'...

AndyW

My Feedback: (1)

I tried Nelson paint and was very pleased with the results. Great finish and very fuel proof. However, be aware that the application and handling is entirely different from dope. With dope, the thinner re-activates the previously applied coats and you get a very good bond. No matter how long between coats.

With the Nelson type paint, you need to apply a second coat the same day for good adhesion. Nelson paints cure after drying. Drying is the first stage. Then they cure much like an epoxy. If you let the finish stand for a day or more, you have to sand the coat to get a rough base for the new coat to stick. If you apply the coat too thick, it'll take quite some time to fully cure all the way through to allow you to sand it without the paper gumming up. This is a lot of work, but it can be done and you can get a spectacular finish that's incredibly fuel proof.

And being a water based paint, spraying it also requires a different technique. Solvents air dry far quicker than water so you need to dust the coats and wait longer between coats. Air temperature and humidity also plays a role. If you live in Arizona, no problems. If you live in Florida (high humidity) or in the north-east and try this paint in the fall, (low temps and high humidity) be aware.

ebeneezer3

I'm covering a Kadet Senior with coveral and sig nitrate and butyrate dope. Top coat will be Randolph Blue and white.
Stick it on with Stix it shrink tight with iron.

Jim Thomerson

The problem with using a hair dryer to dry a wet tissue covered wing is that you heat the air inside the wing. It expands against the tissue. When the wing cools down, the tissue is slack. I don't do that anymore.