Any one know the difference between butyrate dope and nitrate dope and its uses? I will be covering my 1/5 waco soon and the guy at the hobby shop sold me stix-it and butyrate dope but the instructions say nitrate dope. Will it work?
Thanks
Donnie

It will work fine. Nitrate dope has more "solids" in it, so it fills with fewer coats than butyrate dope does. But, butyrate will also work just fine, it will just take another coat or two of butyrate to fill the weave of the Koverall.

Butyrate will shrink a bit more and pull tighter-- that wolud be my choice.

I've used both nitrate and butyrate dope for years and never noticed any significant difference in shrinkage or solids. The use and application is virtually the same for each type (there is more difference between brands than between type). Butyrate dope was developed as a replacement for nitrate dope for full scale aircraft because the dried nitrate film is highly flammable (similar to the old celluloid movie film). The dried butyrate film, while it will burn, has a much retarded flame rate compared to nitrate. A side effect of the new butyrate dope, of interest to modelers, is that while nitrate will soften in presence of glow fuel, butyrate is pretty glow fuel resistant. I didn't say fuel proof because on direct exposure, some butyrate will dull a little. It won't soften, however, and the dulled areas can usually be buffed out with an oily rag.

Of course the solvents used in both types are quite flammable so proper precautions must be taken when spraying and brushing dope of either kind.

I would definitely not use Stix-It to attach the Koverall. It works OK, but the fabric tends to fray a lot and makes a neat joint hard to do. A much better procedure is to use dope to attach it to the structure. The dope binds the fibers so that they may be trimmed with a razor blade without fraying and the edges can be blended with a little more dope on a finger. Also with the dope, there is no danger of the attachment softening with heat and pulling away when you shrink the covering. Though I have used dope for this a lot, lately I've been using a fabric cement made for full scale applications called Fab Tac. It has a faster tack time and is a little easier to use. With either produce, I use a hair color applicator bottle with a small tip to apply the material and smooth it down with my finger. A little acetone or thinner cleans up the fingers.

(A non-tautening version is available in both nitrate and butyrate where heat shrink covering is used and the shrinkage must be controlled.)

The application is the same-- as for the shrinkage, I get my information from Sig--that is the answer I got when I asked the same question.

Thanks for the input. I seems nobody likes stix-it. I've only used monokote in the past. My best guess is to dope the frame, dope the fabric to it, then heat shrink it???
Donnie

I have used Koverall with both nitrate dope to attach and also Stix-it. I prefer the Stix-it as it was muh less of a mess than sticking with the nitrate dope which does not give you an instant attachment like the Stix-it. I still use the heat gun to shrink and then fill the weave with nitrate dope before the color coats and then finally the butyrate dope for the final fuel proof coats.

I will never cover another plane with Monokote or Ultrakote. There is no comparison to the finished product and the lack of wrinkles everytime the weather changes.

I like using the Nitrate on the structure, then attach the cloth with nitrate around the edges. Once dry, I shrivk with a heat gun, then I fill the weave with Nitrate as well. Once the weave is filled, you have lots of options, you can fill the weave completely, then paint for a nice smooth surface, or not and keep the weave for a nice scale look.
If you want to keep the weave look, then just apply the colored butyrate over the nitrate for whatever design you choose. From what I understand, butyrate tends to weigh a little less than paint. I may be trying it on my next plane, we'll see.

Patriot

Ditto !

As to application, I use the same method described by Patriot, works perfectly.

Anybody ever apply the first coat of dope to the airframe using a foam paint brush?

That may well be true of Sig dope. A manufacturer can formulate dope to have almost any shrinkage. Most provide a choice of tautening and non-tautening dope in both nitrate and butyrate. It is not something that is inherently characteristic of the two types. I mostly use “Certified Coatings”, or “Randolph” brands because that’s what my local supplier carries. I have also used “Brodack” and in the past a lot of “Testors”. As I said above, there is more difference between brands than type, but the differences are not significant.

The foam brush might be a good idea, Brush hairs have always been a problem, especially with a new brush. I'll try it next time and see.

As I understand it, nitrate is not fuel proof! However, it's cheaper and lighter than butrate, so it's good to use to fill the weave of the fabric after it's been applied. Then you can put butrate over the nitrate to get a nice, fuel-proof, finish. I think that you can't put nitrate over butrate (not that you'd want to) because it'll craze up.

I have done several planes with Koverall, and to me, Stix-It is the only way to go. Put a coat or two of Stix-It on the edges of where your covering panels will be, then after it dries, put the Koverall on with your sealing iron. The Stix-It grabs the covering and holds it solidly. When you heat-shrink the covering, it won't pull away.

The first plane I covered with Koverall I used only dope to attach the covering, and it was a major pain getting it to stick, especially to compound curves.

Phil

With Stix-it, what happens at the edges where the Koverall overlaps? Does the Stix-it glue come through the first layer of Koverall when reheated the second time?

Once you cover one side of the Koverall applied, you just brush Stix-it on the edge of the Koverall where you will have an overlap, ususally 1/4 to 1/2 inch. Just like plastic covering, you plan so the seams are the least visible (i.e. cover the bottom of the wing first).

Nitrate is fine to appy Koverall, I just think the Stix-it is easier to apply on curves. The nitrate just does not dry fast enough to hold the curves. The Stix-it is instant stick once heat is applied. Once you go over the Koverall with the first coat of nitrate to fill the weave, you will further stick the Koverall to all areas of the frame.

If you are really adventurous like myself, you can attach the Koverall to the lower trailing edge, then wrap it all the way around the leading edge and then tack it to the trailing edge on top. This way you have covered the entire wing with only one piece, and no seams on the leading edge at all. The trailing edge can be carefully trimmed and doped to help hide the edge of the fabric. This process looks really great, but it takes a little more time and care. The results, BEAUTIFUL!!!

Patriot

Hello

I just finished working out the warps in my Sopwith Pup's wing panels. I recovered them with Koverall and butyrate dope. NO PROBLEMS. You might think it's silk or Coverite, but it's not, it's Chiffon.

Kraus