Dharma silk

[GonzoBonzo]

Hey guys,

  Can Dharma silk be used straight from the package, or does it need to be rinsed first.  I'm using 5mm if that makes a difference.

TIA

[Avaiojet]

Hey guys,

  Can Dharma silk be used straight from the package, or does it need to be rinsed first.  I'm using 5mm if that makes a difference.

TIA

I used Dharma silk on this model straight out of the package. Never knew silk was rinsed?

[Tim Wescott]

I used Dharma silk on this model straight out of the package. Never knew silk was rinsed?

Fabric often comes from the mill with stuff on it called "sizing".  It may be as simple as ironing the stuff with starch, to make it easier to sew, it may be some whiz-bang chemical.

If Dharma silk came with sizing, then you might want to get it off before proceeding.

Does it?  I dunno.  The only clue I have is that it's marketed as something to paint on, which would argue against any treatment, or at least any treatment that would be incompatible with the paints that Dharma trading co also sells.

One could always call and ask...

[REX1945]

Hey guys,

  Can Dharma silk be used straight from the package, or does it need to be rinsed first.  I'm using 5mm if that makes a difference.

TIA

    I've used Dharma silk on lots of planes (white - 5mm) and see no real difference between Dahrma and Thai silk (white).

     Thai silk comes in colors, but it is 8mm and drinks up a lot more dope.

     In both cases, I cover with the silk wet.

[john e. holliday]

I was always taught that silk be put on wet/damp.   Nylon was put on dry as it does not shrink.

[11290]

    I've used Dharma silk on lots of planes (white - 5mm) and see no real difference between Dahrma and Thai silk (white).

This:  Silk Habotai 5mm ??

[Tim Wescott]

I was always taught that silk be put on wet/damp.   Nylon was put on dry as it does not shrink.

D'oh.  If it did need to be rinsed, the amount of dampening it gets just putting it on would probably do the job.

[GonzoBonzo]

Sorry for the confusion.  Tim had it.  I've read posts where the silk came with sizing which needed to be rinsed out, or it would cause splotches in a translucent finish. 

I covered the wing tonight.  Looks great.  First time using silk, and yes I did hose it down with a spray bottle.

I have another question though.  I stretched it pretty taught when I applied it, and when the water dried the silk is pretty taught.  I wondering if I should stick with Lite-coat, or go to super-coat on the open bays?

There was quite a bit of blushing.  hoping that will go away after a couple more coats.

[GonzoBonzo]

Ty,

  Do you use a taunting, or non taunting dope on the open bays?  The silk is pretty taught, and I've read posts where the wing, or covering was damaged because of too much taunting dope.

[Jim Kraft]

I rinsed the first time I did the 5 mm silk. After that I never did and could tell no difference. I never use nitrate and always put on several coats of high shrink butyrate dope on before going to low shrink. The first few coats will expand the silk and let it sag, but it will shrink back up as it dries. I also thin the dope more than 50-50 so that any that runs through will not leave a run on the back side. You can use a slightly thicker mixture after the first few coats that fill the weave. Just the way I do it.

[Fredvon4]

Very timely hints

Thanks I am getting ready for first silk with Dharma 5mm on a combat wing...just waiting on new dope from Sig to arrive

Dad and I used silk and tissue in the late 50s early 60s
I was helper
 I wish I had a helper cuz we never seemed to mix enough dope or need three hands to get it all on straight and tight

seemed (in my memroy ) to be a Chinese fire drill the way he had me help cover wings

Floating film in the bath tub for free flight bamboo wings was easier for me

[Jim Kraft]

All good Ty; I think most of us have our own little ways of doping silk. Many times I do like you and at least turn the wing over after doping a strip to let it stay on the surface. It is good therapy to dope a wing and watch the cover firm up as you go along. I enjoy doing that part. And yes, I have found that good old camel hair brushes work best for me. The last ten or so planes have all been silk and dope.

[GonzoBonzo]

Thanks for all the replies.  It's been a learning experience.  I just got done with one coat of super-cote on the open bays.  I did have to flip the wing up if a noticed a puddle on the back side, and let the dope drip back to the outside while I continuously brushed over it.  I started with a 1 inch brush, but went to a 1/2 inch for better control.  It's a ringmaster wing, so it's pretty small.  Over all I'm pretty impressed how easy, and how well the silk looks.

Thanks again for the replies

[john e. holliday]

My self I never worried about what little dope got pushed thru the weave.  After about 10 coats you can't tell anyway.   I did try spraying an initial coat of clear dope many, many years ago.  Never again.

[Avaiojet]

The first few coats will expand the silk and let it sag, but it will shrink back up as it dries.

Jim,

I've never had that experience with the silk I apply, sagging then tightening up with coats of dope.

Probably because I really stretch the silk, so much that I have to pin it in many places.

On the Super Ringmaster to P-40 I did, for some reason, I had a tiny bit of sagging on one panel, but, as you said, couple of coats and it was gone. That was silkspan not silk.

I just covered the Gee Bee Z with some old silkspan with absolutely no sagging issues.

I'm thinking humidity?

Charles

[eric rule]

I'm am sure that what I am placing here is not the only way to use silk. What it is is something that works for me so use it if you want to.

[NED-088]

Good manuals, Eric!

I'll share how we, on the other side of the Atlantic, tackle the subject.

We're using silk only for open bays, cutting it to size with ~ 1/2" overlap.
Moisten the silk, then put it in place and dope the contact areas to stick it to the wood.
Once he silk has dried (no dope as yet!), tissue is cut to size and also moistened. Then it's applied over the silk and also attached with dope to the wood.
Let it dry, then start building up 8 - 10 coats of dope, sanding lightly between every two.
The dope will not drip through the silk as the tissue will be the buffer. Silk and tissue will adhere, dope will shrink them together.
The combination of the two layer covering has two benefits:
The span wise strenght of the silk will make the wing resisting bending loads better, the tissue will 'lock' the weave of the silk, thereby transferring it's torsional strenght to the silk, that has hardly any of its own.
Because of the tissue, the silk won't take up anywhere nearly as much dope as it would on it's own. Almost all of your dope is on the outside.
The doped tissue, to a certain degree, acts as a filler, that is sanded down to a smooth skin.
We haven't found any weight issues, in spite of the two layers

We are experimenting with water borne dope and the first results are very promising. Time will tell....

The 2015 model with the 2016 ( 2 piece) wing:

[Crist Rigotti]

Very cool NED-88!

[Jim Kraft]

Ned; I have used that method in reverse on open framework stabs and elevators as the silk as you say does not have the torsional strength. I put the tissue underneath and put on a couple of coats of dope, and then cover with silk. I believe either way works fine. I can see that the tissue would fill and smooth out faster than silk though. I will have to try that.

Oh yeah! The plane is very cool. Neat job.

[GonzoBonzo]

Well, I lost count at 10 of the number of coats of dope I've applied.  I think 12-13.  How many coats does it usually take to fill the weave?  I used 4 coats of Supercoat to start, then switched to Litecoat.  The Sig dope is really thick, so I've been thinning it about 60-70%.  The last coat was 50-50.  It's shiny in some areas, and dull weave in others.  I think the weave is closed, and could probably fly as is.  Do most people fill the weave till its shiny?

Sorry NED, but I can't see the pictures of your plane.  Problem may be on my end though.   I can see Jet's pics though.  Your method sounds good, but I want the translucent effect the silk provides.  I'll paint some blue trim on the tips, and middle section, and leave the rest clear.

[john e. holliday]

It depends on how thin the dope is.   I keep doping until I see it start to shine a little.   Depending on the brand I thin as much as 50%  so I can brush it.

[eric rule]

Hi Ned:

Yes, I used to do the silk/tissue lamination as well. That was with the older versions of hobby silk we used to get (the stuff with the very loose weave - almost like cheese cloth).

These newer silks have a very tight weave so they do not take anywhere near as much dope to fill the weave. Of course they do not shrink like the older versions so you have to really pull them tight on the structure to eliminate the wrinkle.

Like I said in my post what I do is not the only way to use silk. Any method that you are comfortable using and results in a nice finish is good as far as I am concerned.

[EddyR]

I have covered most of my models FF ,CL and RC with silk since the late 1940's. I had decided to attend the 1988 Nats and had sent Ted Fancher some pictures of my silk stunters to ask if I should use a clear silk finish on a plane for the Nats. He told me he had not seen a clear silk plane at the nats in many years. I entered my orange silk Juno and it was in the center of the second row behind Jimmy Casale 20 pointer. Many people said it looked like wet glass it was so smooth and bright. At that Nats Ted showed me the just released issue of Model Aviation and my two silk covered planes  were in it. Flyers overwhelmed me questions about silk finishing.
 I have never used heavy coats. My first five coats are so thin that the silk is barley filed. The Juno had 30+ coats on it and the plane was very light at 47 ounces.
 The plane was not really a Juno but my Comet based on the Juno but with very different numbers and body gear and thinner airfoil at the tips. A friend was going to enter a I/beam model called the Comet so I went with Juno.
Ed

[NED-088]

Isn't it wonderful, how we share our knowledge and experience all around the globe?

NED-088 used to be my international registration. Until the sporting licence number replaced that. So now it is NED-25369. And luckily I can keep on using that in spite of some sort of FAI number.
By the way, my real name is Bruno.... 

I'm fond of any old style covering, be it tissue or silk....
Just for contest practice we found the combination of the two working just a little better.
As we don't have any appearance points in our contests -don't get me started... -, strenght and durabilty are topping our list.
A glass like finish is nice, but not what we are striving for in the first place.

For GonzoBonzo (like me, you must have areal name    ), I've attached the pictures again and some of the earlier stages.
As you can see, it's just as translucent as tissue or silk alone.

[Avaiojet]

Bruno,

Looks like you play a mean banjo.

I'm terrible at it, but I play bluegrass banjo also.

What's in the banjo case?

Charles

[john e. holliday]

NED-088,  didn't you also join with Ole Dad(aka Dale Gleason) at the 2004 Worlds Banquet playing in the band?   

[NED-088]

Bruno,

Looks like you play a mean banjo.

I'm terrible at it, but I play bluegrass banjo also.

What's in the banjo case?

Charles

This:

A Gibson RB-1 (before I got it, someone decided it being cool to destroy  the original (then) 50 years old inlays and replace them with a vine. Oh well...)
Now it also has a Huber flathead ring instead of the 1/4" brass 11" tone hoop, normally found in these sub Mastertones.
Finally I put on a period correct tailpiece. The luthier who did the restauration in 2007 said, it was meant for me    :

Some soundfiles of my style: Dark Hollow in F     Half A Turn
And some silly little thing I made in my home studio, laying down one track after the other.... Deep Purple In Bluegrass

But this was about silk, wasn't it?

[NED-088]

NED-088,  didn't you also join with Ole Dad(aka Dale Gleason) at the 2004 Worlds Banquet playing in the band?   

Guilty as charged...
I was seated at the 'vegetarians table' together with my team buddy Henk and our friends from France, the Beringers.
Dale and I both played Kevin Hendrix's Rich & Taylor. Almost as good as my Gibson. No, just kidding, it was a 100% pro instrument too.
I still owe Ted and Shareen for taking me back to the hotel, after -of course- the bus had left....
With the '94 WCh, the '04 left the deepest impression so far.

My new little -electric- 'Blitz' easily outperforms the '04 -ST 60- 'Bird', so we'll see what happens in Perth.
The 'Bird' has Polyspan covering, the first hole came within weeks, so I went back to silk/tissue...

[EddyR]

Ned
 I noticed the model Bluegrass BIRD has very small flaps and very long tail moment arm. How did that model fly compared to the other model .
Ed