News:


  • March 28, 2024, 05:21:25 AM

Login with username, password and session length

Author Topic: #&%* Silkspan!!!  (Read 7502 times)

Offline Bootlegger

  • 22 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2710
#&%* Silkspan!!!
« on: November 17, 2010, 05:46:03 AM »
  Don't know what brand it is, but after about two years it starts to split!  Using non-tautening dope from the raw wood out, including in the finish.
  Sure could use some advice!!  What is wrong!?
  Thanks a lot,    R%%%% :-\ :-\
8th Air Force Veteran
Gil Causey
AMA# 6964

Offline Balsa Butcher

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2357
  • High Desert Flier
Re: #&%* Silkspan!!!
« Reply #1 on: November 17, 2010, 08:43:52 AM »
If it was left in clear dope the sun gets to it and it won't last more than 2 seasons. If it was finished in color dope it should last longer but as has been mentioned before, the new stuff isn't as good as the old.  8)
Pete Cunha
Sacramento CA.
AMA 57499

Offline Bootlegger

  • 22 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2710
Re: #&%* Silkspan!!!
« Reply #2 on: November 17, 2010, 08:58:04 AM »
  Thanks a lot guy's, I'll try silk and/or polyspan.  Never used polyspan, and it's been about 40 years since using silk.
 Ty where do you get your silk and polyspan?  And I have a lot of questions about both, so I'll be getting touch with all you fellow's with questions..  Again thanks for the suggestions and advice..   H^^ H^^
8th Air Force Veteran
Gil Causey
AMA# 6964

Offline john e. holliday

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 22752
Re: #&%* Silkspan!!!
« Reply #3 on: November 17, 2010, 09:19:12 AM »
Try Control Line Central (CLC).    Polyspan goes on just like silk or silkspan.  It is a poly-ester material. H^^
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530  Have fun as I have and I am still breaking a record.

Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12804
Re: #&%* Silkspan!!!
« Reply #4 on: November 17, 2010, 09:37:24 AM »
Try Control Line Central (CLC).    Polyspan goes on just like silk or silkspan.  It is a poly-ester material.
Lots of folks have Polyspan.  Just about anyone who caters to stick-and-tissue builders in sizes bigger than peanut scale will have it.

I wouldn't say that Polyspan goes on just like silkspan -- I certainly recall having less trouble getting silkspan on than Polyspan.  The biggest thing to remember about Polyspan is that while it is a heat-shrink material, it doesn't shrink much -- you want to get it as near to perfect as you can before you hit it with the heat gun.  In that it's more like tissue than silkspan.

I've never used silk, but with the prices that I see on Dharma Silk's website I think I should -- I just wish that I could get printed scarves in china silk, for covering airplanes.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Randy Powell

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 10484
  • TreeTop Flyer
Re: #&%* Silkspan!!!
« Reply #5 on: November 17, 2010, 09:42:56 AM »
I had this problem with K&S silkspan. Didn't want to shrink very well, cracked easily after drying and I got splits in it a year or two after application. I went to Sig SGM silkspan and the problem disappeared. I've had no problems with the Sig silkspan.
Member in good standing of P.I.S.T
(Politically Incorrect Stunt Team)
AMA 67711
 Randy Powell

Offline Bootlegger

  • 22 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2710
Re: #&%* Silkspan!!!
« Reply #6 on: November 17, 2010, 09:48:22 AM »
   H^^   Thank You Mr Powell, where can I get Sig s/span?  Our hobby shop doesn't carry it that I know of. Again Guy's thank's... D>K
8th Air Force Veteran
Gil Causey
AMA# 6964

Offline Bill Hodges

  • AMA Member and supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 349
Re: #&%* Silkspan!!!
« Reply #7 on: November 17, 2010, 09:57:00 AM »
Gil:

I order my silkspan from Eric Rule at RSM.  http://rsmdistribution.com/index-2.htm   Look under "Coverings".

Bill Hodges
Bill Hodges
AMA 12450

Offline Russ Danneman

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 188
Re: #&%* Silkspan!!!
« Reply #8 on: November 17, 2010, 10:13:42 AM »
i believe sams hobbies carrys it also.
FLY LOW FLY FAST  RISKY BUSINESS

Offline W.D. Roland

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1152
Re: #&%* Silkspan!!!
« Reply #9 on: November 17, 2010, 10:30:35 AM »
Have a couple of airplanes covered with Silk Span in the early 70s that show only a few bad spots, Although I would think that it is probably brittle now. High shrink dope was used.

Is the new stuff really so bad to fail in only a few years?

I was considering Silk Span on the FW.
David Roland
51336

Offline Douglas Ames

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1299
Re: #&%* Silkspan!!!
« Reply #10 on: November 17, 2010, 10:46:50 AM »
Doesn't Silkspan have a grain to it? Could it be that's why it's splitting - installed in the wrong direction?
AMA 656546

If you do a little bit every day it will get done, or you can do it tomorrow.

Offline Balsa Butcher

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2357
  • High Desert Flier
Re: #&%* Silkspan!!!
« Reply #11 on: November 17, 2010, 11:03:17 AM »
The "new" silkspan does not have a noticeable grain in it. Thanks for the tip re: Sig vs K&S silkspan, I'll stick to Sig as long as they produce it. Now, if I could only get some more Lite-Coat dope... 8)
Pete Cunha
Sacramento CA.
AMA 57499

Offline Randy Powell

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 10484
  • TreeTop Flyer
Re: #&%* Silkspan!!!
« Reply #12 on: November 17, 2010, 12:30:44 PM »
I get Sig Silkspan from (surprise!): Sig. I order it online from the Sig online store. Good service, too.
Member in good standing of P.I.S.T
(Politically Incorrect Stunt Team)
AMA 67711
 Randy Powell

Offline W.D. Roland

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1152
Re: #&%* Silkspan!!!
« Reply #13 on: November 17, 2010, 02:27:01 PM »
Pete
If I remember correctly the Sig Lite Dope was regular dope that had a plasticizer added.
It may have been castor added but not sure.
I have done the castor trick to regular Aero Gloss dope on F.F. models and it worked just as good as the Sig stuff.
David Roland
51336

Offline kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1464
Re: #&%* Silkspan!!!
« Reply #14 on: November 17, 2010, 02:31:43 PM »
        I refer to that as the potato chip stage. I had this happen several times in the last few years. I think as noted above Sig dope prevents this and I highly recommend Dave Brown Flex All. Its a plasticizer for all types of dopes. It will surely help prevent the problem. Ken

Offline billbyles

  • AMA Member
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 648
Re: #&%* Silkspan!!!
« Reply #15 on: November 17, 2010, 03:00:45 PM »
        I refer to that as the potato chip stage. I had this happen several times in the last few years. I think as noted above Sig dope prevents this and I highly recommend Dave Brown Flex All. Its a plasticizer for all types of dopes. It will surely help prevent the problem. Ken

Hi Ken,

Exactly!  The silkspan, whether it be light, medium, or heavy, does not provide the strength of the cover.  The silkspan is merely a medium to carry the dope which provides the real strength of the covering.  For the first coats of dope on the open bays I use tautening type butyrate dope to ensure that the silkspan gets taut & remains that way.  Then I switch to non-tautening butyrate with a little of Dave Brown's plasticizer added.  I have just about always used medium silkspan, and have had no problems with the above process.

Because the dope provides the strength of the covering when using silkspan, if you are trying to get away with only three or four coats of dope then the covering will likely not have much strength.
Bill Byles
AMA 20913
So. Cal.

Offline Neville Legg

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 593
Re: #&%* Silkspan!!!
« Reply #16 on: November 17, 2010, 04:09:30 PM »
I have seen stunt models covered with light weight jap tissue, the kind used on peanut rubber scale models, then doubled covered with Modelspan, which is a strong rag tissue, available here in England. This is only on the open bays. Less dope is is required to fill the tissue grain, in 50 years of aeromodelling I've never had a problem with good old Modelspan! ;D only with the nitrate dope cracking! :( It comes in light and heavy weight.

Cheers
"I think, therefore I have problems"

(not) Descartes

Offline Balsa Butcher

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2357
  • High Desert Flier
Re: #&%* Silkspan!!!
« Reply #17 on: November 17, 2010, 04:16:31 PM »
Sort of veering off topic here but what the heck. I have read a few folks mentioning that adding a plasticizing agent (Flex-all, Castor oil, have used both) will turn Randolph's or Brodak into Sig. Don't know how that works. Plasticizing agent makes dope more flexible and fights the tendency for it to "crack". Haven't had that problem. My preference for Sig is because I have found it to be more fuel proof than the other brands. How does adding a plasticizer make it more fuel proof?...Bill, anyone?
Pete Cunha
Sacramento CA.
AMA 57499

Offline Jim Kraft

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3411
  • AMA78415
Re: #&%* Silkspan!!!
« Reply #18 on: November 17, 2010, 05:56:26 PM »
I covered this huge Taurus wing with Sig medium weight silkspan about 12 years ago, and finished all of the open part with clear Sig dope. Still looks good and has been flown a lot with big vibrating spark motors, and a Fox 59.
Jim Kraft

Offline billbyles

  • AMA Member
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 648
Re: #&%* Silkspan!!!
« Reply #19 on: November 17, 2010, 06:25:00 PM »
Sort of veering off topic here but what the heck. I have read a few folks mentioning that adding a plasticizing agent (Flex-all, Castor oil, have used both) will turn Randolph's or Brodak into Sig. Don't know how that works. Plasticizing agent makes dope more flexible and fights the tendency for it to "crack". Haven't had that problem. My preference for Sig is because I have found it to be more fuel proof than the other brands. How does adding a plasticizer make it more fuel proof?...Bill, anyone?

Hi Pete,

I think that the two subjects about "fuel-proof" & "plasticizer" sort of got mixed here.  Adding plasticizer does not make the dope any more "fuel-proof" (actually, "fuel-resistant" would be more accurate here), it just reduces the rate of tautening of the dope finish & makes it more flexible.  However, over time, the plasticizer tends to leach out & sublime and the dope becomes less flexible...more of a problem for full-scale airplanes since they may go for 20 or more years between recovers.
Bill Byles
AMA 20913
So. Cal.

Offline W.D. Roland

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1152
Re: #&%* Silkspan!!!
« Reply #20 on: November 17, 2010, 07:00:28 PM »


The strength of the silk span from the dope is due to bonding the fibers in the material, same as with fiberglass, CF or other fibers that are bonded by resins . When more resin then enough to wet all fibers is used the only result is added weight and can become brittle.
When more dope than enough to bond fibers is used on silk span it fills the 'weave' or grain so we get a pretty paint job. Dope alone by itself is very brittle.

Bill
Never would of thought about the plasticizer leaching out....interesting..
Thanks for that thought and it does explain some things have observed in full scale and model finishes where splits in old finish will start on curves around tubing and such.
David Roland
51336

Offline Jim Thomerson

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 2087
Re: #&%* Silkspan!!!
« Reply #21 on: November 17, 2010, 07:02:53 PM »
I notice it is more a problen on the top of wings.  I think it is a matter of UV, or whatever, from the sun.  I think making wing covers would be a good investment.

Offline Balsa Butcher

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2357
  • High Desert Flier
Re: #&%* Silkspan!!!
« Reply #22 on: November 17, 2010, 08:47:12 PM »
Thanks all, I don't have a problem with flexibility or longevity of dope and silkspan either.  Flew a 15 year old Hemstraught PT-19 at a contest last month after my newer model crashed. Sig dope/silkspan finish still good, plane flew great. Do have a problem with the fuel proof qualities of dope other than Sig, especially since moving to the land of 15% nitro. Gonna miss my Lite-coat, that's fur sure. 8)
Pete Cunha
Sacramento CA.
AMA 57499

Offline Michael Massey

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 223
Re: #&%* Silkspan!!!
« Reply #23 on: November 17, 2010, 11:28:46 PM »
After too many instances of mysterious "hanger rash" I changed to silk.  It is a new learning curve and a bit of a pain.  The largest is that it takes (at least for me) about 10 coats of dope to get nice and tight and wrinkle free.  The upside is that it is super strong.  I have (confession coming up) crashed a number of times and the silk, to this point, has absolutely saved the wing.  Strong, strong, strong.

The other downside is that with that many coats of dope, the wing can sometimes "warp" while the dope tightens.  I microwave some wet towels, throw them on the warp (which I have clamped in the desired de-warped position) and let it sit while the towels cool.  The towels go over the multi dope finish with no ill effects.  Warp gone, nice strong finish.
Eagle Point, Oregon
AMA 914713

Offline Jim Kraft

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3411
  • AMA78415
Re: #&%* Silkspan!!!
« Reply #24 on: November 18, 2010, 05:37:55 AM »
Hey Pete; Does Sig not make Lite-coat anymore? They still have it on their web site. I assume you can still order it, although it is a little pricey. I think I will try some Randolph from Spruce Specialty, as it is quite a bit cheaper for the low shrink dope. I have been using Sig Lite-coat for years, but for some reason the price just went way up, compared to their regular Super-coat.
Jim Kraft

Offline Balsa Butcher

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2357
  • High Desert Flier
Re: #&%* Silkspan!!!
« Reply #25 on: November 18, 2010, 08:20:50 AM »
Hi Jim, that was in reference to a discussion over in the Painting and Finishing forum. Apparently Sig has lost their dope supplier and we may not be able to buy Sig dope any longer.  :-[
Pete Cunha
Sacramento CA.
AMA 57499

Offline Jim Kraft

  • 2015
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 3411
  • AMA78415
Re: #&%* Silkspan!!!
« Reply #26 on: November 19, 2010, 06:40:14 AM »
AAAAAAARRRRRRRRRhhhhhhh! That is bad news. Been using it for years, and always had good luck with it. I have used Randolph in the past, and guess I will have to go back to that. I will probably have a lot of planes the same colors with having to buy them in quarts.
Jim Kraft


Advertise Here
Tags:
 


Advertise Here