Please help, I would like to do my T-Craft in a silk and dope finish but I can not find an online supplier of Nitrate dope.

According to info I got from the Net:
Although Butyrate dope is completely fuelproof and good for basically any type model, is lightweight and easy to apply, dries fast and great flexibility, and can be used for a high variety of covering materials, it says (the article I have from the Net) that Butyrate dope has a HIGH degree of shrinkage which means it continues to shrink after drying and can cause warps.

Nitrate dope, although is NOT fuelproof, basically does the same thing MINUS the high shrinkage rate which means it stops shrinking when dry.

But I can not find an online company that sells it. I can find PLENTY of online companies (including my favorite one, Tower Hobbies) that sell Butyrate dope, but I do not want the high shrinkage after drying.

It also states that open structures should first be coated with 2 coats of butyrate to enhance shrinkage, followed by the Nitrate dope coats. OR . . .

A LITE-COAT low shrink Butyrate dope is available to help minimize the high shrinkage problem. Recommending that you consider substituting lite-coat, low shrink butyrate dope as much as possible to help avoid warps. Fully-sheeted models can use lite-coat exclusively while open structures it is recommended that you use 2 coats of butyrate 1st to help shrink the covering tight, then switch to lite-coat for the rest of the job.

Help . . . . . . .

Which should I follow?
1] Use butyrate dope, which can be gotten at Tower Hobbies, exclusively for the whole project and hope for no warps . . .
2]Try to find an online company that sells Nitrate dope and use that exclusively for the whole project, followed by a fuel-proof paint . . .
3]1st 2 coats of dope use butyrate to enhance shrinkage, followed by the top coats of Nitrate, followed by the fuelproof paint . . .
4]1st 2 coats of dope use butyrate to enhance shrinkage, followed by the top coats of lite-coat, low shrink butyrate.

The problem with 3 & 4 is that I'd have to buy two products plus the thinner. If I use butyrate from my trusted Tower Hobbies that would be best cause they have everything needed for that choice.

Please help me choose, either the butyrate which is easiest to get or Nitrate and if I should use nitrate, please show me where I can buy it online.

Also where can I find Nitrate dope thinner. And has anybody heard of silray material (mixture of silk and rayon)?

EDIT . . . Sig Manufacturing does carry Nitrate dope but I can not find a way to order it directly from their site.

Brodak also has nitrate dope. The Sig thinner works for nitrate as well as their butyrate. Check with Randolphs, also Wicks Aircraft Supplies, Penn Valley Hobby Shop, Micro-X, FAI supplies, Campbell Custom Products, etc, etc. I have never tried it but everyone says do not put nitrate over butyrate or you get a sticky mess. You can go butyrate all the way. I've done it many times. Sig Litecoat does not shrink much, but I still plasticize it with Dave Brown plasticizer. Do so for sure with Sig Supercoat. From some of the suppliers above you can get both tautening and non-tautening nitrate.

Might be good to take a look at the Silk and Dope thread in the tips and techniques forum.

What is the difference between tautening and non-tautening nitrate. Is tautening just another word for stretching. Forgive my ignorance .

Tautening means shrinking. Tautening is the word the word "they" use.

You should be able to scroll down to the bottom of the page where it says "Add Items To Your Order." Push that button then continue in the usual manner for ordering anything over the Internet.

They not only sell the dope, but I think they still have a bunch of HowTo pages that explain all the additives. (And when you paint with dope, you're going to NEED to know about additives!)

http://www.brodak.com/

Sig nitrate dope p/n's

Pint SIGND001 $10.59
Quart SIGND002 $17.99

DON'T SNIFF TOO DEEP

At the bottom of pg - enter quantity before clicking "add to order". Proceed from there.

Sig Lite-Coat should work fine with your silk. I use it all the time with Jap tissue. There it is pretty much non-shrinking. I find I have to shrink the the tissue with alcohol before doping. There is also a retarder available, I beleive, from Sig.

You should build a simple flat square out of scrap and cover it and experiment. This is a great way to proceed with new covering methods. also check out the forum at smallflyingarts.com, there are some master bone coverers over there.

-Derek

The first plane I built with my father was a Kadet Mark II but that was about 20 years ago.
I remember that we did a silkspan and dope finish on it, but I don't remember what dope we used, but I do know it came out beautiful and very tight. Unfortunately there was an accident with it at home and the covering was torn on the wing, then I sold my radio equipment and gave the plane away with the setup, giving up the hobby until recently where I started it up again AND LOVE IT MORE THAN EVER.


I have ordered the Nitrate dope and thinner from Sig and the Dave Brown Skyloft from Tower Hobbies http://www2.towerhobbies.com/cgi-bin...?&I=LXB896&P=7 which I think would look great on this plane.

Now I just need to find either Ko-Flex (plasticizer) or non-tautening butyrate dope to go over the Nitrate.

Is it safe to put Butyrate over Nitrate or should I . . .
A]just stick with the Nitrate ONLY and paint with Rustoleum (paint I plan on using) and that's it?
B]apply the Rustoleum, then the Ko-flex plasticizer (where do I find it?) and that's it?
C]Nitrate, Rustoleum, non-tautening Butyrate (where do I find it?) and that's it?
D]or some other ideas you use, but I am using Nitrate as I already ordered it?

Thank you.

People routinely put butyrate over nitrate, but do a test patch as some brands may be incompatible. Rustoleum over nitrate is fine, so I am told. The flexall is for butyrate or acrylics. I have not used Rustoleum, but many do. I understand the metallics are not fuel proof.

Do yourself a huge favor and toss the Dave Brown Skyloft (or tack it to the bottom of a piece of overstuffed furniture, since that is what the material is normally used for). Here's why:
1) It is HEAVY. It may not seem like it, but weigh it--it is considerably heavier than Sig Koverall. I don't know of any unfinished covering material sold for model airplanes that weighs as much.
2) It must be applied wet to shrink it, and then you have no control. Anything that is not really strong is a candidate for warping, and you can't tell until it is too late.
3) The size of the holes in the material is extremely irregular and some holes are impossible to fill with dope unless you add talc. You can put on coat after coat, and even daub the holes with extra dope and still have holes.

Seriously, just chalk up the 4 bucks to experience. The only thing going for it is the price and you can beat that with a role of you-know-what.

I like Sig Koverall, a fabric, and Polyspan, which looks just like silkspan but is much stronger. Both will heat-shrink.

Sig LiteCoat and all the colored dopes are non-tautening butyrate, and yes, they can be applied over nitrate.

But Sig Nitrate is also non-tautening, so you won't be getting any shrinkage from your dopes.

I had a disaster with Rustoleum that turned out not to be resistant to 10% nitro; also it may not hold up over open bays where it is subject to flexing.

Good luck. I love doped finishes and hardly ever use iron-on. Jim

Hello, You can use the nitrate dope under the butyrate but the buyrate is NOT compatibile under nitrate.Good luck.

http://www.sigmfg.com/cgi-bin/dpsmar...D001_2ehtml_01

According to the info at Sig, it says that the shrinkage of Nitrate is not as great as Butyrate, but it does not say it is non-tautening.

I have e-mailed Tower Hobbies to try to substitute the Skyloft with silk but I don't know if that can be done. Has anyone used Skyloft with good results.

I have already ordered the Nitrate so can I apply the first two coats with regular Butyrate dope followed up with a coat or two of Nitrate, then the coats of color? I would rather not spend the extra money for Butyrate if it really isn't necessary.

Or should I disregard the Nitrate altogether and just use Butyrate? But then what would I do with the Nitrate that is coming? And also Butyrate continues to shrink and tighten EVEN AFTER DRYING, which Nitrate doesn't. So I think I will try the Nitrate since that is already ordered, and Sig says it is great for covering with.

Later -

Steve

From snitch; From the tips & techniques forum:

"QUOTE":
Nitrate is used for first coats because it shrinks better than butyrate, and after it shrinks dry, it stops.

Butyrate does not dry as tight, and is not as stable once dry - it can shrink for a long time.

Retarder is also used for spraying, so that the dope has time to flow.

Rejuvenator is used to soften up an old coat, so that a new one will bind.
"UNQUOTE"

He claims that Nitrate is better than Butyrate.

Any other opinions? I will read all.

Thank you

I mostly agree with the quote, with one important exception: nitrate will either shrink or not shrink depending upon whether or not the manufacturer added a plasticizer--and the two major hobby suppliers don't tell you! Sig Nitrate shrinks very little. I got some Brodak thinking it would, but it turns out it doesn't shrink either.

The only source of nitrate dope I know of that will shrink is Aerodyne. But the last can I got from them had a rusty tint to it from the drum the original supply came in. I don't like it because it's impossible to brush it on without getting very obvious brush marks.

If anyone knows a source for straight, unadulterated nitrate dope in quart sizes I'm very interested.

Aside from the Aerodyne nitrate, the only dope I've used that definitely shrinks is Sig Supercoat, but it's a butyrate.

Shrinking is really important to me because I'm trying to use silk from a fabric outlet (Thai Silks) and their silk doesn't shrink much at all.

Jim