Author Topic: Silk Problem- Now What? (Read 1270 times)

Jerry Rauch · « **on:** July 09, 2009, 08:50:11 PM »

I covered a Thunderbird wing with the RSM silk as per the instructions, wet and pulled tight before the doped edges dried, looking really good, after the silk dried.
Brushed on the first light coat of Sig Supercoat, thinned 50%. Majority of the silk tightened back up, but I now have areas that have some light sags which were not there before. Tried slightly warming with a hair dryer, no help....Anybody have any ideas of what I can do now, other than pull it all off and start over with Japanese silk?

john e. holliday · « **Reply #1 on:** July 10, 2009, 09:20:45 AM »

Are you using nitrate or butyrate dope? I have found that covering will sag a little until enough coats of dope are put on. Butyrate usually shrinks up drum tight for me. I quit using nitrate as I have had problems with it. DOC Holliday

Mark Scarborough · « **Reply #2 on:** July 10, 2009, 09:57:31 AM »

More coats of dope, and make sure at least the first several are tautening

Jerry Rauch · « **Reply #3 on:** July 10, 2009, 05:38:16 PM »

The first coat was Sig butyrate clear thinned 50% with sig thinner. I put it on kind of light, as I've read that if it is put on heavy, it can puddle or drip thru the covering and cause problems. I guess I'll try more coats. Thanks for the input..

tom hampshire · « **Reply #4 on:** July 11, 2009, 05:49:05 AM »

Hi Jerry - It usually takes about 5-6 coats of tautening dope to get it to shrink up. I use low shrink (brodaks) for the later top coats to lessen the tendency to warp. Using all high shrink makes crazing and low puncture resistance more likely. You want a compromise between tension without wrinkles and a waxy, pliable feel to the silk which means it will last for many years. 25 years is attainable with some practice. For the first few coats, try a foam brush, and whisk the dope on with only one stroke. Multiple brush strokes drives dope through the silk and causes runs inside the wing. Fixing them is easy. Strike the foam brush off dry against the side of the can, hold the airplane so the run is on the downward side, press the foam brush against the run and pull it away slowly. It will pull the run through the silk and repair the problem. Tom H.

Brian Massey · « **Reply #5 on:** July 12, 2009, 06:29:21 PM »

Well I am just going through what you describe. I doped the perimeter of the open bays and put the silk on dry, pulling out as many of the wrinkles as I could. I then wet it by spraying with a water bottle. The silk pulled nice and tight after air drying, so I applied the first coat of dope; Reynolds taunting Butyrate thinned about 50/50 (This still leaves a pretty thick mixture). After the first coat dried, it was very loose and full of wrinkles. I was close to tearing it off and starting over, but forged ahead and applied a second coat: better. Then on the third coat it really pulled tight, so tight it pulled the outboard wing trailing edge down.

Just so you'll know, I used silk from Thai Silks (www.thaisilks.com); Habotai 8mm white, and am at this point pleased.

I've now had the wing in a jig for two days applying very hot towels, and the warp is gone; so back to several more coats of dope before the color.

I know you've already had good advice, but just wanted to add my 2 cents worth.

Brian

Jerry Rauch · « **Reply #6 on:** July 13, 2009, 07:55:21 PM »

I put on the third coat of butyrate clear, still thinned 50%, and the sags are gone. Looks pretty good. Thanks for all the advice..

Clint Ormosen · « **Reply #7 on:** July 13, 2009, 10:19:47 PM »

Quote from: Brian Massey on July 12, 2009, 06:29:21 PM

The silk pulled nice and tight after air drying, so I applied the first coat of dope; Reynolds taunting Butyrate thinned about 50/50

Reynolds dope?

Brian Massey · « **Reply #8 on:** July 15, 2009, 04:02:06 PM »

Hi Clint;

Did I type Reynolds? Oops, I meant Randolphs from Aircraft Spurce.

Brian

jim gilmore · « **Reply #9 on:** July 15, 2009, 08:20:26 PM »

Yeah Randolphs like the reindeer. Not reynolds like the foil.

Alan Hahn · « **Reply #10 on:** July 21, 2009, 07:12:50 AM »

Quote from: jim gilmore on July 15, 2009, 08:20:26 PM

Yeah Randolphs like the reindeer. Not reynolds like the foil.

Hmm, Randolph the red-nosed reindeer just doesn't sound right!

Let's see,

Reynolds for aluminum foil, Randolph for dope, and Rudolph for red-nosed reindeer

James C. Johnson · « **Reply #11 on:** July 21, 2009, 10:17:54 AM »

All the silk I have put on was wet...... and this might sound crazy but I soak it... each piece is cut for the wing panel.. bottom first... then a scrunch it into a little ball and squeeze out as much water as I can... stretch it out and start doping it down around the edges. I do all four panels before doping the whole thing.. I use Sig Litecote. I have wings that are almost 30 years old still holding up.. one on an RC and the other was on a Jr Flitestreak .. which I stripped because the body was worn out but the wing was still in great shape.. I have always done my silk, parachute, nylon.. this way .. I just keep pulling/stretching until the wrinkles are gone and it is ready to dope.. drum tight.. there is a definite learning curve to silk..

How is the 8mm silk from Thia Silks.. would 5mm be better.. just wondering.. I like silk better than polyspan..

Jim

Jerry Rauch · « **Reply #12 on:** August 01, 2009, 06:54:54 AM »

The silk I used was from RSM, I think it is Chinese silk, and is supposed to be pre shrunk. I have ordered silk from Sig, it is Esaki, Japanese silk. Only problemis whenever I order it, they are out of stock. I ordered 2 yards last, waited almost a month. This time I ordered another yard along with more dope, for a Sig Ryan ST I'm starting and back ordered again. I really don't care for the chinese stuff, although at 12.00 a yard, it is half the cost of the Esaki. Then again, maybe the Esaki silk won't need as many coats of clear.

Brian Massey · « **Reply #13 on:** August 01, 2009, 09:25:53 AM »

I just completed a Trophy Trainer covered in 8mm Thai silk. I agree that there is a learning curve to silk, but my first effort result says to take the time to get the hang of it. I have no wrinkles and it is drum tight dispite all the mistakes I made. I doped the perimeter and put the silk on dry, working out all the wrinkles I could. I kept putting on dope (thinned) in areas I needed to pull tighter. It seemed to work, but I'm sure some of the other methods are as good, or better. By the way, Habotia 8mm Chinese silk is only $6.00 at yard (54" wide) from Thai Silks. http://www.thaisilks.com/index.php?cPath=1_2 The 5mm is only $2.95 a yard, 36" wide.

My brother used the 5mm stuff and felt that it took a lot of dope to fill the weave.

Brian

Author Topic: Silk Problem- Now What? (Read 1270 times)

Jerry Rauch

Silk Problem- Now What?

john e. holliday

Re: Silk Problem- Now What?

Mark Scarborough

Re: Silk Problem- Now What?

Jerry Rauch

Re: Silk Problem- Now What?

tom hampshire

Re: Silk Problem- Now What?

Brian Massey

Re: Silk Problem- Now What?

Jerry Rauch

Re: Silk Problem- Now What?

Clint Ormosen

Re: Silk Problem- Now What?

Brian Massey

Re: Silk Problem- Now What?

jim gilmore

Re: Silk Problem- Now What?

Alan Hahn

Re: Silk Problem- Now What?

James C. Johnson

Re: Silk Problem- Now What?

Jerry Rauch

Re: Silk Problem- Now What?

Brian Massey

Re: Silk Problem- Now What?