I use silk and always like the way it finally looks, but I am wondering if I do something wrong. My method: apply it wet, attach with nitrate. Nothing on the open bays but water. Let it dry and it is as tight as a drum. Then apply butyrate. Here is where I get worried. Open bays go slack and develop wrinkles. The dope is completely dry but the wrinkles remain. It takes some time, I guess for the dope to gas off, but it finally does tighten up nice. But man, in the meantime it sure is worrisome. I just applied silk to my J.D. Falcon and I've got the same wrinkles. If this doesn't tighten up I sure have a mess to fix. Any comments or suggestions?
Thanks in advance.
Jim

Yea, that happens and Jim is probably right. Might try a hair dryer on low to completely dry it out. Just make sure you keep it moving. Don't want one area to tighten up too quickly or it can cause warps. Just keep in moving and it will probably tighten up very nicely. sure makes you squirm though.

Thanks for the suggestions. Covering looks a little better this morning, but still not there. Silk came from RSM, so I don't believe that it had sizing, but I'll drop a note to Eric just to be sure.
I'll try the hair dryer and then move on to the thinner, if necessary. I'll report back later. Until then, I'll continue to squirm!
Jim

Hi Jim,

What brand of clear?  Some are more *tautening* than others........  don't know if it makes a difference in your case.

Have you tryed attaching with shrink dope on the wood instead of nitrate ??

You don't say what brand of butyrate you are using, but Sig explicitly recommends using 1-3 coats of their clear SuperCoat Butyrate (their clear shrinking type) over open framework as opposed to their Litecoat brand of butyrate dope over silk (see directions on cans of Sig Nitrate and Litecoat).

Exactly why I posed the question, Alan.   There IS a difference!

Hi Jim,

What brand of clear?  Some are more *tautening* than others........  don't know if it makes a difference in your case.

Hi Bill,
Well, I used Sig nitrate to attach (have used this before and works great). Nothing on open bays but water during attachment process. Let it dry for several days. All surfaces of wing, tail were tight as a drum, looked great. Then coated open bays with Brodak butyrate (50/50 w/2% retarder). Oops, then the wrinkles appeared and not just in one spot but over all the bays wing and tail. Let it dry for a day and most of the wrinkles disappeared. But there are still enough that make it look, well not so good.
Update: Tried the hair dryer and was careful to alternated top and bottom bays to avoid any wing warp. Results: Not much.  Then tried the Brodak thinner. Humm... seemed to work at first, but then the wrinkles reappeared. So I switched thinners to Dupont 3608S. Gee, something began to work! So, I used some more and things are looking a little better. Now I think I am just going to let it sit and de-gas. Think there could have been something wrong with the Brodak thinner??? Anyone have any other ideas???
Jim

Jim:
If it does have lots of size, they sure don't tell you in the instructions. Nothing about rinse either. Only instruct to keep it very wet during application. Like you always do with silk. Does say if you don't have a drum tight wet covering, then it will develop wrinkles with first dope coat. Maybe my perception of drum tight is not theirs. Regardless, I have some wrinkles. They are beginning to go away, but still a few nagging ones, like on the top OB wing panel first bay from center section.
By the way, how does one remove silk? Not that I am all that excited to do it, but I will if necessary. Or can you selectively cut out panels and replace them.?
Jim

My experience is the silk will slack with each coat of dope till it's completely sealed. I have found some silks will shrink more than others. The silk we get today I think is different than that from years ago as I don't think it shrinks the same or as much. I have some really old stuff and some new I got from Darma I used on an experiment testing attaching with Polyacrilic. And the old stuff almost crushed the frames and I also had wrinkles with the new stuff and the sizing was washed out. But I only use Sig Nitrate till its sealed.

Hi Bill,
Well, I used Sig nitrate to attach (have used this before and works great). Nothing on open bays but water during attachment process. Let it dry for several days. All surfaces of wing, tail were tight as a drum, looked great. Then coated open bays with Brodak butyrate (50/50 w/2% retarder). Oops, then the wrinkles appeared and not just in one spot but over all the bays wing and tail. Let it dry for a day and most of the wrinkles disappeared. But there are still enough that make it look, well not so good.
Update: Tried the hair dryer and was careful to alternated top and bottom bays to avoid any wing warp. Results: Not much.  Then tried the Brodak thinner. Humm... seemed to work at first, but then the wrinkles reappeared. So I switched thinners to Dupont 3608S. Gee, something began to work! So, I used some more and things are looking a little better. Now I think I am just going to let it sit and de-gas. Think there could have been something wrong with the Brodak thinner??? Anyone have any other ideas???
Jim

Hi Jim,

I am about 99% positive that the Brodak clear is not as *tautening* as the Sig SUPERcoat.  Not the Lite coat, it will not shrink much.  I suspect the Brodak is similar to the Lite Coat.  On the Sig cans it describes the differences in Super and Lite Coat clears. (or at least it did! LOL!! )

I use nothing BUT Sig nitrate for everything except open bays.  I attach the covering with the nitrate and then brush three or four thinned coats of Super Coat on the open bays only.  There is a difference in the shrinking rate of different butyrate clears.

AND, I only use 3608S to thin everything.  I know there are some here who will disagree with some, or all, of what I just wrote, but it has looked great for going on 20 years.  So to them I say: "You have the Perfect Right to be Perfectly Wrong!" 

Bill <><

JMHO: Brodak may not be as taughtening as Super Coat but it is taughtening so time will help.  Retarder? Why?  In my experience it causes more probems than it helps.  Try without.  Also, Brodak thinner seems a lot more potent than Sig - a real paint guru would be able to explain but I do know that I can spray Sig LIGHTLY over decals with no problems but Brodak will curdle them up like cottage cheese. This ties in with your experience with Brodak loosening up the covering.  3608s is good stuff  but may not be available in your area.  Otherwise, keep Sig thinner w/Sig, Brodak Thinner w/ Brodak.50/50, no retarder. I have never had a problem putting Sig over Brodak or vice versa.  In your situation I would probably opt for staying with Sig only because the Brodak (probably because of the "hotter" thinner) seems to loosen the covering up more. 

All good information...thanks. I ordered some Sig Super Coat (hope it doesn't take a month to get it). I'll let the surfaces dry (already looking pretty good), until the Sig arrives. Then I'll put a coat or two of the Super Coat over the Brodak. I'll bet this will shrink it up real good.
Jim

Larry Renger, using Andy's compuer:

Read the instructions when using RSM silk.  It does NOT work as Easki and similar silk of old.  It is pre-shruk, and only expands very slightly when wetted out.  He also specifies the dope to use, and believe him.

I'm gonna jump in here and say that the silk I've used has a 'grain' to it and is best put on span wise and not chord wise. Maybe you have it 90 degress off ? Just my humble opinion.

Gene O'Keefe

As in silkspan, if you tear at the end of the material, you will notice that the fabric has little strands that are longer in one direction and not the other. The long direction is spanwise. Works for me. Never had one wrinkle yet.
Gene

All good information...thanks. I ordered some Sig Super Coat (hope it doesn't take a month to get it). I'll let the surfaces dry (already looking pretty good), until the Sig arrives. Then I'll put a coat or two of the Super Coat over the Brodak. I'll bet this will shrink it up real good.
Jim

OK, finally completed. I used 3 coats of Sig Super Coat over the Brodak clear, then let it dry for 4-5 weeks, the wrinkles disappeared. Then Brodak color coats, let that dry for 4-5 weeks and then top clear coats with Sig Lite coat. No problems with mixing brands. The secret may be that I was able to let significant dry time between brands. I am not yet a successful finisher, but it sure is fun to go through this process and learning all the way. Since this J.D. Falcon was a Blue Sky's kit and my first inverted engine model, I have had great input and help from Tom Niebuhr (thank you very much Tom!). When I told him about my color selections (lime green/lemon yellow), he said, "yikes, a Falcon in canary colors!", so I added the silver canopy and silver gear struts(can't see in picture), to give it a little more of a predator look. BTW, she flies a lot better than I can, yet. Will be great fun getting to know the "Canary Falcon!"
Jim

Hi Jim.  I recovered my Sleekster about three weeks ago with silk from the Dharma company.  Beautiful stuff. But I too had four places where some wrinkles crept in after the first coats of dope were applied. This is the first time I have sprayed on the first coats of clear. But as each coat was applied, the wrinkles got smaller and all but one had disappeared. The one left on the tip,  I pulled tonight by using thinner on the silk to get it loose and repulled it tight. Took all of five minutes.  FWIW

Hi TY,

One thing to remember........... you have been using silk since we had to feed the worms to get it!   You know tricks and techniques to apply it that many others do not know.  I got to thinking, and I realized that you , and several of us who have done this since well into the middle of the last millennium, really take a lot for granted when we build and finish these things.  Softening the silk, or silkspan, and sometimes tissue (if you are very careful), to restretch and remove a wrinkle is someting we do without giving it a thought.  Think about it...... there will come a day when no one will have any experience with the things we do as second nature.  Probably not in out lifetime, but surely one day.  Stained glass was practiced in a lot of places at one time, but the secrets of the REAL thing is lost.......

Bill <><

Let me toss in a few more things about dope that have not been covered, and maybe a bit about covering.  The following is not from my "expertise" in using dope, silk, silkspan, nylon and now polyester, but is taken from the Randolph/ poly fiber manual.  The manual recommends glueing fabric to the airframe.  Of course we are not going to glue our fabric, but use dope to attach it.  And we are not going to get into the plane and fly it. But, if using polyester fabric which Brodak and others sell, after putting 3 to 5 coats of NITRATE dope on the wood, thinned 50/50, attach the polyester with NITRATE thinned 50/50.  After it is shrunk, which is (on a full scale aircraft) done with a calibrated iron at a specific temperature, the temp I do not have available, not a heat gun, you MUST brush NITRATE dope onto the poly until it is entirely encapsulated.  Butrate will not stick to polyester fabric.  I learned this the hard way when I thought I'd be slick and spray the nitrate on.  This was before I got the manual.  But, when I sprayed the butrate, holes developed in the paint down to the fabric.  The more I sprayed butrate, the worse it got.  Randolph is the only dope that can be used with poly fiber according to the FAA.  No other brand of dope may be used over or under the Randolph dope.  Stitz has another dope to be used with their poly fabric that cannot be mixed with Randolph.  This according to the FAA.  I have also been advised that Poly Fiber and Stitz are the same product and have just had different names applied to them.  The polyester fabric sold by Brodak (the only poly fabric with which I have experience) appears by sight and feel to be the same thing as Poly Fiber, only much lighter.  Now for the personal stuff.  Up until a couple of years ago, I never used nitrate dope.  I never used poly fabric either.  All silk and butrate.  I used Aero Gloss (AKA Randolph and Brodak).  The old stuff had some taughtening.  The new stuff has to be bought to specifically taughten.  Only non taughtening dope can be used on Poly Fiber.  Randolph sells both taughtening and non taughtening.  I believe Brodak's is non taughtening.  The taughtening stuff is tinted.  I can tell you nothing about Sig.

Hope this helps.  The manual is in my truck if any one needs any more info.  I don't get into this computer on a daily basis, sometimes 3 to 4 weeks pass, but you can E-mail me and I will respond when I get into my E-mail.

Or... you may think I'm full of it trying to play expert, which I can assure you, I am NOT.

Bob