Is all silkspan equal?

I was going to put this in the othe current silkspan topic but thought I'd not divert the other discussion. Is "Silkspan" a brand name or are there different manufacturers of silkspan? I have some medium silkspan I purchased recently in the local hobby store and some that I've had stored away for many years. The old stuff feels differrent to my fingers: smoother surface, less "fuzz" and more even density. When the new stuff is held up to the light it appears "blotchy" (is that a word?). Some areas appear to have a denser fiber count. The old stuff seems to take more abuse when wet: lifting and resticking without tearing.

Have you guys switched over to some new "wonder material" in place of silkspan? If so, what?

Silkspan is the term used to describe it, not a particular brand name.
The "new" silkspan doesn't seem to be of the same quality as the old stuff.
Many more are now using "poly span" which is a polyester material with certain characteristics of silkspan. Main differences are; it is applied dry, it is heat shrunk, it is much harder to puncture, it is much harder to go around complex curves.
Bill <><

it is much harder to go around complex curves.

<sigh> sounded great up to that last point

I don't do so well on the compound curves as it is...

Aaron's Geo XL in the other posts is covered with Poly Span. Including the tips, but they were tough to get right. Most people cover teh tips with silkspan, and the rest with Poly Span.
Bill <><

Ron - I recently had a chance to compare silkspan. While building the prototype for the Brodak "Vampire", I used Brodak's own brand of silkspan for the first time. It is definitley superior to any silkspan I've used in the past. I normally buy whatever silkspan the LHS sells so I cannot ascertain the brands.
The Brodaks seems to shrink more uniformly and is much better on compound curves. Also, I was able to seal the weave with three coats of Brodak clear, sprayed on.
Bob Z

LAST EDITED ON Feb-03-04 AT 03:14 PM (CDT)
 
I liked the Brodak silkspan better than the other new ones. It looks whiter and a bit less "blotchy" (less glue or whatever matrix is used?) than the other brands now. However, even though I had it stretched, wrinkle free, while still damp and it dried very taut, it still wrinkled whenever I applied dope. While it dried tighter after each succeeding application, it was disconcerting to see those wrinkles! As stated in the "Silkspan Problems" thread, none of the new silkspans I've found during the past year are as good in any respect that I can tell as the stuff I bought two years ago.

What I'd like to ask is this concerns the basic thickness and puncture resistance of your Brodak silkspan. Brodaks generously sent me a trial batch, which I have used to patch my ill crashed practice SkyRay several times. They told me that they only marketed "Medium" under their name and sold Sig silkspan in the other thicknesses. When I mic'ed it, I found the thickness to be around .0015" - .0022", which is the thickness of the other brands' light stuff. It took less dope to fill and survived crashes that tore the older, thicker (more brittle??) covering. A computer wire then punctured it when it flipped out of my hand during some under-desk re-attachment work. So, have you found your Brodak silkspan to be as thin as mine, and do you find it adequately puncture resistant?

Thanks.

SK

Serge: .015" - .022"? I think you missed a decimal place.
If not, better get a new micrometer.
Bob Z

LAST EDITED ON Feb-03-04 AT 03:16 PM (CDT)
 
Ooooops! Corrected above.

So what is your measurement and how do you view its puncture resistance??

SK

LAST EDITED ON Feb-03-04 AT 02:47 AM (CDT)
 
If you do a SSW search for "Silkspan Problems", you will see quite a lot on just this subject. I found your observations to be true of all the new silkspans, when compared to what I bought a couple years ago. That goes for Sig, K&S, and even Brodak's (see above). This stuff does NOT - repeat, NOT, did I mention NOT!? - work as well. I do NOT like it. I used it...what else can I say? Oh, yeah, I really hate the stuff.

SK

In October I covered my new plane with some Sig Tissue that had just come in the mail.I find it doesn't saturate as well as the old stuff they used to send me. Maybe a different binding material .

I find the newer silkspan harder to read the grain than the older stuff. Don't know what brand. Tearing it seemed to yield almost the same results in either direction.

Finding and buying old silkspan, still rolled in the long boxes, is a classic swap meet score. It shows up a lot, often by RCers who don't use it any more, and sell it cheap.

So, keep an eye out when you attend your next swap.

That's what I found to be true. I also think that it has less surface area or perhaps permeability on the rough side, so that you have to be more careful when applying succeeding coats of dope over silkspan-covered balsa to make sure that it does not lift.

SK

Serge, and others,
are you sure that you're not comparing the silkspan to the Japanese tissue? I'm pretty sure you are, and that's the source of your frustration and confusion.
If you study what SIG has to offer, you will see that out of the non-colored tissues, you can get three grades of Silkspan and one grade of Japanese tissue that they call (I think) Lite-span. When I was browsing around Brodak's hobby shop last summer, I saw all four kinds. I touched, studied and compared them. Indeed, the regular SIG and Brodak silkspan are blotchy, don't have any preferred direction, and have about the same level of gloss on either side.
The Lite-span (and it really IS Japanese tissue, since the box clearly stated "Made in Japan") does have a preferred grain direction, and is much smoother on one side than the other. It is also about 4-5 times more expensive than silkspan.
And if you watched Bob Hunt's tape where Larry Kruse (?) shows how to cover with tissue, the first thing he does is compares silkspan and Japanese tissue, and says that silkspan is NO GOOD!
Serge, you can borrow that tape if you want.

LAST EDITED ON Feb-03-04 AT 03:22 PM (CDT)
 
Mike-

Thanks, but I do have the tape (you may have borrowed it once) and have viewed it several times. I used a couple of Larry's techniques on the Yak to see what worked best. It's a good and useful tape.

Sorry - no, I am sure that I am not confusing silkspan with Japanese tissue, since for one thing, I had both light and medium weights of the "good stuff". I have the last partial sheet of some really nice medium weight Sig silkspan that I bought from Wayne when I first came back to finish the Yak-9. It has definite grain direction, longer strands, and less of whatever holds them together. Hence it is not "blotchy". It does not crackle like Christmas wrapping paper and the new "silkspan". It adheres better, follows compound curves better, and looks better. It is the same thickness as what is still called medium (except for my Brodak sample). I had pieces in both light and heavy. In short, it is just like the silkspan I remember from my youth. I have compared it often with samples of Sig and K&S I have brought home since, and there is a marked contrast.

BTW, the new K&S is what I used on the P-Force. I had a couple lifting problems, despite care taken to avoid them, but it came out "OK" - not great.

SK

Oops, sorry - I didn't mean to offer to lend you your own tape

Back to the subject of substandard silkspans - what I meant to say is: maybe it's time to give up on the regular cheap silkspan, and switch to using the Jap tissue, while it's still available?
Technologies change constantly, including the materials and processes. What used to be avialable for years may not be in use anymore for one reason or another, and manufacturers can only offer the closest substitute available. I'm surprised the silkspan, however bad it is, is still available altogether! I don't think any other model class (RC, free flight, etc) uses it anymore. Only dinosaurs like us.
Look what happened to automotive chemicals - regular cheap lacquer thinner could be used for our dopes just fine, and now that is has this little "VOC" label on it, it doesn't work anymore!

I think I will be using 100% Jap tissue on my new planes.

P.S. When am I gonna get to fly that sexy little P-Force?

Mike-

You may fly it any time - that is, when the blizzards are past! It balances about 1/4" ahead of where Mikey says it should and 3/8" ahead of where his does. With the FP .35, it'll be 1/4 oz lighter, but I'll still need about .5 oz tail weight, raising it to a hefty 40 oz - ouch. Mikey says that's OK for what's on it now. Gary T. says leave it nose heavy. If I leave the LA .40 on it, I'll need to figure out how to slow it down. It cuts a lot of grass on takeoff with the 11" x 4"! You can fly it and give another educated opinion.

Some of that weight is in perhaps excessive clear on the wing to smooth the texture. The silkspan's still plenty tight, but some of the "candy" red migrated into the clear, making further wet sanding ill advised, I think.

You will need to tell me more about your Japanese tissue experiences, as I had thought it not as strong as silkspan. Wrong?

Serge

A couple of thoughts:

Japanese tissue will not be as strong as medium silkspan unless you have some bad silkspan. And then we are all in trouble. It is good for rubber powered planes and covering sheeted areas. I would not recommend it over open bays.

The 35 FP ought to be able to handle 40 ounces, even with that wing area.

If you are having trouble flying out of grass, put some wheels on the plane. Seriously, put some 3 inch Dave Brown Lite Flite wheels on it--the wide, flat, ugly ones. Matt does this when he flies out of grass, and the 3 inch wheels have the same size hub as the 2 inch variety, but just more foam. Very light for the size, but it gets the nose out of the grass.

LAST EDITED ON Feb-03-04 AT 08:21 PM (CDT)
 
I'm sure...I apply it wet.

The video you mention is excellent. I had never used Japanese tissue and found it very informative, especially how to apply tissue with a glue stick. Haven't tried the glue stick yet...but someday.

George

Edit: Mike, I reread your #11 post. I think Larry was referring to light silkspan not being good for weak frameworks because of the shrinkage. I don't think he was putting down silkspan in general. Perhaps I'm wrong. I'll have to watch the video again.
If you are going to switch to Japanese tissue, you might consider using two applications of tissue. The first is applied spanwise, the second chordwise. Not a new idea, they did this MANY moons ago.
Good luck with it.

Sig calls its (actually, made in Japan) colored stuff Plyspan. It is about the same as Medium. The Lite Span, also Sig, is the really thin stuff, with a slick side.

I like Plyspan. You can play color games with it by dyeing it in the same color, and getting greater saturation. Or, dye it in a constrasting color.

Some people in the Sun Belt areas have complained about fading, though. We don't see the sun enough up here to fret about such things. Currell