Covering with Koveral from SIG
I am busy building a 1/5th Scale SE5a and is currently at the covering phase.
I want to use KOVERALL. I have used it last year on a SIG Smith Miniplane I build for a friend.
For adhesive and sealer I used stuff I got from a local hobby dealer and he called it,
AeroLoc - Same as Sig Stix-it
Aerofix - Apparently it is Nitrate Dope
AeroSeal - Nitrate dope with some filler added.The problem is that I can not get the stuff any more from Him and I do not have much experience with dope.
Here in South Africa this kind of stuff is difficult to get hold of.
I spoke to someone and he told me that I can use Sanding Sealer for adhesive. According to him it is more or less the same as Nitrate Dope.
My question here is, Is this true? Will it work? Does someone have any advice for me on this?
He also said I can add some Talcum powder to the Sanding sealer and use it as sealer to seal the weave. Is this true? Any advice Please?
I also read on the internet that I can use normal PVA base white wood glue instead of Stix-it. Is this true? Will this work?
I will really appreciate any help and advice on this Please.
It seems to me that it would be easier, and more practical, to switch to Solartex.
Solartex has a heat activated adhesive, eliminating the need for Stix-it.
It does not need to be sealed, eliminating the need for dope, sanding sealer, etc.
It does not require priming, and accepts most paints readily.
In my opinion, it is an easier, less expensive way to obtain an "authentic" fabric finish.
I like Stix-it or Balsa-rite.
I don't know about using sanding sealer for adhesive, but talc in dope does work as a sanding sealer. I wouldn't use it over open frameworks - it might crack with the flexing of the fabric.
PVA can be a heat actuated adhesive. I've used it to attach 1/16" sheet with a hot iron. (Spread it on and let it dry.) I've not tried it with fabric.
Sounds like you have some experimenting to do!
Thanks for the advice.
I am really new to this type of covering and is still learning.
What is the differnence between Nitrate dope, clear dope and sanding sealer?
I did use solartex before but was not happy with the finish and here in South Africe it is much more expensive than the koverall.
Once the Koverall is on the frame and heat shrunk get nitrate dope and nitrate dope thinners mixed 50% and roll onto fabric. I have used foam 'brushes' but you have to work fast because they will swell up and start to disintigrate. They're very inexpensive so that makes them attractive enough for their faults. Brushing the nitrate tends to push it thru the fabric which makes it a little heavier and takes longer to dry. Apply 2 or 3 coats to seal the fabric over open structures. Lightly sand between coats with fresh paper. This will cut the fuzzies. Be careful to not create new fuzzies. Experience will be your guide. Once dry you can start using butyrate dope over this. 'Sanding sealer' is fillers and butyrate dope where I live. You can apply butyrate over nitrate but not the other way round! Use sanding sealer to mimic metalized or non fabric areas that have fabric on them if you don't wish to go the route of fabricating panels to cover fabric. Have fun! You'll love Koverall- I do! I have heard of folks using milk or glue to fill fabric weave but have not tried it since I'm happy with the aforementioned process.
Good description, ARUP. I have just applied Koverall with nitrate dope. It can also be heat activated, to seal down edges that don't want to go down. I don't feel it's necessary to have a separate material for applying the fabric.
I haven't tried Solartex yet, but have tried another 'tex' type. It got very dirty in the weave, and I have read that people often seal the surface of Solartex to avoid this. So that means you're going to paint anyway. My feeling is that if I have to do that, the high price of the Solartex is not worth it.
To each his own.
To use these dopes the normal sequence is to attach, tighten and seal the fabric covering with clear nitrate dope. This is normally done using two or three coats that are thinned 50%. Then one or two coats of colored butyrate dope are used for the final decoration and for fuel proofing. Colored butyrate dope tends to be heavy so it is used in thin layers with only enough to acheive the desired color. Then a top coat of clear glossy, semi glossy or matt butyrate dope can be used as a top coat. As mentioned before, butyrate dope can be applied over the top of nitrate dope, but not the other way around.
If dope is hard to find in your area try an airport that does aircraft maintenance. You can often buy dope from them and although it is the same stuff, it is usually quite a bit less expensive than the dope that is packaged for model use.
After a week of search I managed to find some Nitrate and Talcum powder.
Now I will be able to my SE5a the same way I did the SIG Smith Miniplane for a friend.
After all the advice and ready here on the forum, I now understand dope much beter.
One "old timers" trick I have heard of but haven't (yet) tried is supposed to greatly reduce the amount of dope needed to seal fabric is gelatin. Supposedly you take the cut pieces of fabric and thoroughly wet them with a gelatin solution (Knox or Jello if you don't mind the tint)and let them dry. Then attach them to the airframe with lacquer. I guess with Koverall you could still heat shrink it, But then I don't know if the heat would do anything to the gelatin.
Appears this was a technique used in the BK days (before Koverall) and used on silk. I have used Koverall before but I still prefer silk since it can be lighter (Sig silk is almost 1/3 the weight of Koverall but is ridiculously expensive) but is available in many weights if you need more strength than Koverall. Outfits like Dharma Trading sell the various weights of silk. And the lightest (supposedly the same weight and strength of Sig's is 1/10 the cost.
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