papaone

Hello
I'm very impressed by japonese painting.
Do you know what's they use before painting to recover balsa of wings and stab ..
Do they use fiberglass with resin or silk and coating nitrocellulogic ?
What is liquid in the pot ?

TankHunter

My Feedback: (1)

looks like fiber glass but i have no idea what is in the little cup... could be something like poly c... but i dont know...

dreadnaut

My Feedback: (5)

Could be silk, but more likely 1/2 or 3/4 oz glass fiber. No clue on the resin.

tuny

the cup looks like finishing ressin or any other 30 min epoxy whith some alcohol added to make it more liquid and easy to apply. when you add alcohol the mixture turns a little white

the cloth should be fiberglass 1/2 oz maybe

gene webber

My Feedback: (3)

Hi Guys,

Maybe one of the Japanese builders will reply. I researched a couple of the Japanese sites including the one Papaone presented pictures from. My mother inlaw who is from Japan read the captions and told me they are using silk fabric and old fashioned dope. The mixture in the cup is clear dope with talcum powder added as a light weight filler. Some use Japanese tissue similar to our silkspan. Most prefer silk because of high strength to weight ratio. Got to give great credit to the Japanese builders, they build superbly crafted pattern planes that fly just as good as they look.

Gene

bla bla

Yes, could well be dope. Silk and dope has been use by the scale community since Adam.
There was even an artical some years back about using dope/talc' with glass fiber. The result were excellent but time consumming to achieve.
Several thin coat where required with a complete sand down between each.
The big deal is the wieght is low compared with epoxy and its very easly to sand off.
Big deal?

We acheive extraordinary finished on our 70's .61 models using only tissue paper and old fashioned wall paper paste!
A light sand down, shoot one coat of pimer, sand 95% of it away and the shoot the colour... perfect,
Never any cracking of the sheeted wings or body and so, so light... make you think who the hell decided it would be smart to use glass cloth and epoxy!
Again, thats sill used today at the highest levels of European F4C.

Gregg G

My Feedback: (7)

Hey Gene,
Did it say how many applications of filler they had to use to fill in the silkspan?
Greg

dreadnaut

My Feedback: (5)

Ok, silk then. I remember using it once as a kid. Silk and dope is really labor intensive, but it is strong and light. I do not know what the tensile strenth of silk is, but I suspect that is is comparable to fg. does anyone know this?

rainedave

My Feedback: (1)

I cover my models with silk and dope, but not to that degree of glass-like finish. It's not surprising that the finest brand of silk manufactured for model airplanes (that I know of) is Esaki, a Japanese company. Sig has distributed Esaki for many years, Aerodyne Online still sells it:

http://www.freeflightmodels.com/page..._materials.htm

woodie

There is a great video available from Don Ramsey that shows step by step how to paint balsa covered wings very lightly. I got an early version of this video and was very impressed by the completeness of the individual steps and the additional information included about supplies, vendors, expected weights by component, weight gain step by step, etc.

you can read about it here http://members.cox.net/don.ramsey/WingVideo.htm

Don

Rendegade

I have used dope and tissue on smaller planes with great success. The only thing I would say is that epoxy with 3/4" cloth is a better alternative for heavy use aircraft as it gived the airframe a nice hard shell. which stands up to the rigours of handling a little better.

THe only thing I have noticed with using the epoxy method is that after a while visible stress cracks appear in the paint and I'm not sure if that's because the epoxy has cracked or whether it's just from dissimilar expansion rates of balsa and epoxy or not.

Either way, I jsut wick some thin CA over them, and forget about them untill it's time to do some refurbishing.

gene webber

My Feedback: (3)

Greg, If I remember correctly 3 to 4 coats of the dope/talc mixture, allowing thorough drying between coats. I don't have a real fresh memory, this was some time ago. I believe there are some threads here on RCU about the dope and silk process if you do a search. Silk is an interesting substance, resilient as kevlar, ductile as steel and expensive as love.

Remember dope is not totally fuel proof and attacks styrofoam, so be careful if covering foam core structures with this method. Most of the Japanese planes are built-up balsa construction. Currently available polyurethanes are the most durable finishes available for our use, but require some equipment and knowledge for good results. Hence the rise of iron-on coverings.

I prefer a painted surface over iron-on for all the obvious reasons, but there is a higher price in both time and materials.

You might consider the video by Don Ramsey mentioned by Woodie in a previous post if your curiosity gets to you.

Gene

Gregg G

My Feedback: (7)

thanks Gene,
I've done alot of finishing with fiberglass and the old Superpoxy and talc. Worked great. I'm just wondering if there is a substantial weight advantage going to the silkspan and dope method.
Greg

rainedave

My Feedback: (1)

Silk and dope is remarkably light. That is why it is still commonly used on FF models. You need to use nitrate, not butyrate, dope to fill since it contains more solids. But, still add talc.

Here's a table of weights. You can see it weighs half as much as Monokote (minus paint):

http://www.skyhooks.ca/cover.htm#anchor363595

Then there's also the stuff that C/L folks use, carbon veil cloth:

http://www.brodak.com/shop_productde...ProductID=5951

or, Silkspan:

http://www.brodak.com/shop_productde...ProductID=7461

jonlowe

My Feedback: (12)

I was silking models with dope and talc when that was the only thing around, other than silkspan and tissue. Several things I remember about why I hated it are:

You had to seal the balsa first, which, at the time, meant doping, then sanding, because dope raised the grain. The silk was so thin that balsa grain would show thru if you didn't. Sometimes we also filled the grain with dope/talc first.
You needed to wet the silk to get it to lay flat, because of the way dope air dried rather than curing. You really didn't have time to work with dope after it was applied. The silk had to be flat first before you touched it with dope.
Silk shrunk when wet, and the dope shrunk further, causing warps if you weren't careful.
We used talc to fill the dope and the weave of the fabric. Usually took several coats to fill the weave. Once you thought you had it filled, you'd let it set a few days, and the dope would shrink more, showing the weave again.

The whole process was labor intensive, stunk up the whole house, and the finished result was not totally fuel proof, especially with higher nitro content, and could warp. There are reasons why people went to fiberglass and epoxy, with working time, no need to prefill the balsa underneath, no shrinking, no wetting of the covering, etc, etc. Finished result is much tougher and fuel proof.

I don't think the pictures are showing dope and silk. I might be wrong, but it looks like fiberglass. Most plastics, like the cup shown, also would not stand up to dope and the thinners we used. We used glass containers for mixing dope and talc.

I just got the Ramsey video. I agree that he has some good points on how to do a very light fiberglass/epoxy covering job. Looks much easier than what I remember about dope/talc/silk.

Jon Lowe

rainedave

My Feedback: (1)

Wow

To each his own, I guess. Silk/dope is the easiest and most enjoyable method of covering I've ever tried. But, it's not the fastest.

papaone

Hello
Thanks a lot for yours answers and advices. I'm very happy
Gene Weber, I picked pictures on this japanese site Paint shop Ino****a.
http://www12.plala.or.jp/ps-ino/index.html
May be there are answers to my questions but I don't read Japanese
Claude

papaone

Hello
My friend Jerome Bilquey (2iéme in french Championship category national) communicated this link
http://f3a.sakura.ne.jp/radiocontrol...ustar-z00.html
Very nice building of Austar but in japanese language even pictures !!!
See particularly this page where there are explanations (end of page)
http://f3a.sakura.ne.jp/radiocontrol...uster0628.html

jonlowe

My Feedback: (12)

I ran http://f3a.sakura.ne.jp/radiocontrol...ustar-z00.html
thru this translator:

http://www.worldlingo.com/en/website...ranslator.html

It says that they were using silk. From what I could make out, they were using epoxy resin with talc and silk. The translation doesn't do everything, but gives you the general idea of what they are talking about.

Jon Lowe

bla bla

Still.... think I'll stay with film.

PatternFlyer

My Feedback: (182)

It is silk and sanding sealer. Sealer first, sand, iron on silk to remove any wrinkle, sanding sealer etc.
Probably dope mixed with something like talcum powder. It will sand easier with less weight than just the dope.
I used silk with dope only back in 80s. Lots of Japanese still use silk to cover and paint entire airframe. Those high cost Japanese hand built planes used silk & dope.

My friend still prefers silk rather than glass.

Ihncheol Park

PatternFlyer

My Feedback: (182)

The one at Masahiro's site is urethan sanding sealer with silk.

mimile

OK