dopeing 101
 

Hello all,

Im planning on covering my GP 60 Cub with fabric or koverall and have read a bit about dope and what not but am not compleatly clear. Can someone please give me the "cliff notes" for dopeing. What do i apply to the framework first? how do i stick the koverall? do i paint the koverall with dope? how fuelproof is it? do i need a "clear cote" ? what is this about nitrate and butrite or something like that? two different kinds? how compatable are they with eachother? any help would be greatly appreciated.

RE: dopeing 101
 

I just started using Koverall for open control surfaces- it's a lot easier than I thought...

After sanding/cleaning, apply two coats of dope to the surface to be covered, sanding lightly after the first coat dries (which only takes a few minutes). Then, overlay the Koverall onto the surface and paint the edges of the fabric with the dope; the dope will penetrate the covering and re-activate the dope applied to the surface earlier. When dry, you can heat shrink the un-doped center portion of the section you are covering to remove wrinkles, whatever. When you are finished that, apply dope to the entire surface, so the fabric is just saturated. When dry, lightly sand, and dope two more times. On the final doping, you might add a little talcum powder to the dope for better filling, but I haven't needed to do this (I don't thin my dope as others do).

When heat shrinking flexible parts, make sure you do both sides at the same time, so you don't warp the piece in the process.

I use Butyrate, which is fuel-proof but has a strong odor. Nitrate dope is not fuel-proof (you'll need a fuel-proof paint/clear coat) but I've heard has much less odor. I wouldn't mix chemical compositions, though- doesn't seem like it would work right.

RE: dopeing 101
 

There is an excellent book on covering and finishing models called "There are no Secrets" by Harry Higley. I highly reccommend that you read this book for all of the information that you will need . It is available from RC Modeller Magazine and also from some Book Stores and Hobby Shops.
This is avery good reference book that you will use many times.
I think that the book is also available direct from Harry B. Higley & Sons, Inc. , P.O.Box 532, Glenwood, IL, 60425.

RE: dopeing 101
 

thank you very much for your input. it did help. since it will be awhile untill im ready to cover anyway ive got time to research and learn all i can. thanks for your help guys.

RE: dopeing 101
 

By all means purchase the book. It is worth it's weight in gold. If you use Nitrate dope to seal the model with it will seal the grain of the balsa very quickly as it is thicker than buterate. Then put the fabric on with Nitrate and then shrink the fabric. Then use Nitrate to fill the weave of the fabric and you are all set for the final sanding and finish. Nitrate is less expensive as well and has better filling capabilities. Go for it and hope you have a great finish.
JEB:D

RE: dopeing 101
 

[I use Butyrate, which is fuel-proof but has a strong odor. Nitrate dope is not fuel-proof (you'll need a fuel-proof paint/clear coat) but I've heard has much less odor. I wouldn't mix chemical compositions, though- doesn't seem like it would work right. ]


Butyrate over nitrate is fine, just don't put nitrate over butrate!

jess

RE: dopeing 101
 

Hmmm... interesting. Thanks for the tip.

RE: dopeing 101
 

The advice to use nitrate dope first is very good and will give you best results. After the fabric is installed and a couple of coats of nitrate dope, you can overcoat with Butyrate (but you can NOT put Nitrate over Butyrate) to fuel proof. You do have to be careful of doping when the humidity is high or you will get lots of blushing.

RE: dopeing 101
 

Nitrate dope is used in covering full size aircraft because of the way it bonds to the fabric. Then the butyrate goes over that. Silver dope is used for UV protection-probably not really needed on a model.

Apply 3-4 coats of nitrate to the framework, sand lightly. Then you can use a mix of mostly thinner and dope-maybe 90% thinner-to adhere the cloth. Then heat shrink. Or, you could use Coverite or Stiks-It and iron the Koverall on and then heat shrink and dope it.

If you want the best finish, you can spray clear dope over the color. The beautiful shiny dope finishes have a lot of clear on them. The clear is what is sanded and buffed to that high gloss. The clear isn't strictly necessary, but is a good idea for gloss and durability.

Nitrate dope is not glow-fuel proof at all, but it's fine with gas power. Butyrate is probably better described as fuel resistant. Nitro content fuel over about 10% can mar the finish if not cleaned up right away. BTW, if you use some castor oil in your fuel, it helps add shine and flexibility to the finish.

There is so much info and so many ways of doing this that it's impossible to get it all in one post. One source of great info is at www.windyurtnowski.com Windy is one of the acknowledged masters of the dope finish, and offers videos of his methods in great detail. Well worth a few bucks to see a master at work.

There's nothing prettier than than a well-done dope finish.

RE: dopeing 101
 

Hey guys, I have a question (or a couple of questions).

What about using silk?

Is there any data out there about going to the fabric store and buying a bunch of silk .... then depending on the dope to shrink the silk taught?

If silk is an option, is it heavier, lighter, or about the same as using ... say ... 21st Century Coverite fabric?

RE: dopeing 101
 

Doping 101 Question

Glider wing that needs to be recovered, thinking of using Polyester dress lining ($1 a yd 38" wide white) from Walmart. Going to use Stix-It to attach the material, I have clear butyrate can I use this or should I get Nitrate ? It been 20+ yrs since I used Dope for planes, I've been using monokite lately. I also have a trashed 12 inch wing section to test on, so I don't mess up.


Anyones help answering this question would be Appreciated


Thanks

Mike

RE: dopeing 101
 

[Is there any data out there about going to the fabric store and buying a bunch of silk .... then depending on the dope to shrink the silk taught?]

Apply the silk wet (water) it will shrink as it dries. Do a search for silk on RCU lots of good information.

BTW a couple of hours ago I finished mi first silk covering in over 20 years. I may never do another plastic covering!

jess

RE: dopeing 101
 

You can use butyrate, but nitrate is much cheaper. If you're doing a good sized plane, dope can get expensive.

Again, price is the biggest drawback to silk. Polyester cloth like Koverall is much cheaper. Silk has a much finer weave to it, is light, and looks awesome when it's done well.

I like Koverall, attached with Stix-it, filled with several coats of nitrate (brushed on) and then butyrate color sprayed on. Relatively cheap, looks great, and gets raves at the field. The only thing I don't like about it is the stink!

Phil

RE: dopeing 101
 

Here's a link to a pretty extensive item on covering with silk:

http://www.eskimo.com/~smallnet/Archive/post381.html

Scroll down a ways to find the article.
Also:
http://www.aalmps.com/silk.htm

RE: dopeing 101
 

Phil,

Thank you for the response, the doping material was freebies. Since I mention to someone that I was recovering a glider wing and have plans for a 101" DFS-230 Assault glider. They suggested the Polyester dress lining its about same weigh as Koverall, cost is what got me $ 1 a sq yd (WalMart- best colors white and gray)

Thanks again

Mike