Applying SLC over Silkspan or Polyspan

[Mike Griffin]

Can some one please tell me how they apply SLC over tissue and manage to get all the wrinkles out of it?  I assume you need to iron it on over the sub covering but at what temperature?  Do you put it on at one temp and then go back over it to shrink it at a higher temperature like you would Ultracote?  I am looking for the technique and also the temperatures.

Thank you

Mike

[Lyle Spiegel]

I have Gieske Nobler component kit sold by Doug Moon. It came with SLC, I scuffed up the film and then applied light silkspan with thinned clear, then about four more brushed thinned clear coats, lightly sanding between coats. Smooth as glass, ready for primer & color. what is logic of SLC over silkspan?

[Mike Griffin]

Strength and you can paint right over it

Mike

[David_Stack]

Good Morning Mike;

  Larry Renger started a thread about this very thing over in the "Paint & Finishing" forum.  Several pages to wade through, but there are at least a few builders who tried it and reported back with results.  May want to peruse the thread, and then contact some of those who provided "testimonials"

  Thread is at: https://stunthanger.com/smf/paint-and-finishing/slc-over-polyspan/

r/
Dave

[MikeyPratt]

Can some one please tell me how they apply SLC over tissue and manage to get all the wrinkles out of it?  I assume you need to iron it on over the sub covering but at what temperature?  Do you put it on at one temp and then go back over it to shrink it at a higher temperature like you would Ultracote?  I am looking for the technique and also the temperatures.

Thank you

Mike

Mike,
Here is what I did.  First applyed two coats of SIg Dope over the frame work (sanded between each coat with 320 grit sandpaper).  Attached the plyspan over the alone the outside of the wing panel and attached the plyspan with 50/50 dope.  After the entire wing was covered, I sprayed water on the plyspan and allowed it to shrink tight.  Note.  On the tips I had to recoat the tip with water to shrink the covering to my standards. 
Set the iron temp at about 150 degrees just enough to active the the glue of the SLC.  Starting on the bottom of the wing, cut a piece of SLC the size of the wing panel.  Begin by attaching the film at the root of the leading edge, stretch the film two the trailing edge and seal it down with the iron.  Next, stretch the film to the tip and seal the film to the wing tip in the center of the wing tip.  Stretch the film to the leading edge of the tip and seal it along the leading edge of the tip, followed by the trailing edge of the root.  The next trick is the center of the wing panel and attach the film at leading edge and stretch the film to the trailing edge.  What you are trying to do is pull out all the wrinkles of the film over the top of the plyspan, do not try to make the film drum tight until the top of the wing panel is covered.
Once the wing panel is covered top and bottom, set the iron a little hotter at 180 degrees and work slowly a rib at a time from the top and bottom of the wing panel so as not to warp the wing.  Work your way towards the tip letting the iron do the work by gliding the iron over the film at a slow speed.  Once you have the feeling of speed and heat right it's a simple process.  You can alway increase the heat of the iron and speed up after it ironed in place.
I think it works great and looks awesome.  Sorry it is a little wordy.

Mikey
 

[Mike Griffin]

Thank you all for the replies and help.  I am good with Ultracote but my experiments with the SLC have not been so good as I have trouble getting the wrinkles out on solid surfaces.  I thought my heat settings were not right.  This stuff acts differently that Ultracote.  Thank you again

Mike

[john e. holliday]

If you do a search for Larry Renger and myself you will see the posts we made.    On three different planes I have not used any dope of any kind to finish the planes.  The base covering(silk-span, poly-span and doctor tissue) is pudown first ising a heat sensitive glue from fabric stores called,  Mod-Podge.   You have to let it dry/cure before attempting to put base covering down.    By the way after the mess the first panel I did trying to put the base covering on damp didn't work for me.   I now put it down with enough heat to activate the Mod-Podge.   Work around the perimeter and once perimeter is down then go over the covering with the iron.  Don't, I repeat don't use an air gun.   Yes the covering may relax a little, but when the SLC/mylar is put down you will see it works.

The SLC/mylar is put down doing the perimeter and taking out as many wrinkles as you can.  The wing tips need a little wotk to get most wrinkles down/out.   Once the SLC/mylar is down shrink it going from edges to the center of the wing panel.   By the way do one panel at a time.  So far my wings have not warped on me.  Now if you do get a bad wrinkle the hot air gun will come into play,  but be very careful.  I am now spraying the primer coats on two planes now.   A side note, get a package of the foam scrubber pads your wife uses on dishes to go all over the SLC/mylar to knock the shine down a little.  Go lightly as you will raise edges if you get to ambitious with it.

[Larry Renger]

The key to this covering is to make sure you bond the SLC to the Polyspan everywhere. You are creating a composite covering material by doing this.  DO NOT dope the open areas of the fiber covering before the SLC overcoat. It will trap air bubbles and add nothing but weight to the finish.

[Eric Viglione]

Mike - I understand why you want the strength of the SLC for the open bays, but if I may be so bold to offer an alternative way to think about using it.

I too found it hard to keep the bubbles, wrinkles, etc out of the solid surfaces with SLC, especially down in the hot humid tropics.

The only reason to want the "strength" is for puncture resistance, right? Because plastic film really doesn't add any rigidity. So...

My solution is to put the SLC on FIRST and ONLY on the open bays, and only go about 1" over-size to the open bays to give it plenty of grip.

THEN treat the wing as if it's just a normal built up wing, and put on your 1 coat of full strength dope on the wood and film, then a 2nd and 3rd coat of thinned dope on ONLY the wood, (because the SLC doesn't absorb the dope and 1 coat is plenty) THEN put your silkspan/polyspan/doctor paper, whatever over top of that with some very thin dope and finish per usual.

It will easily hide the edge of where the SLC stops, and will give you a wing that will withstand your friends pens falling out of their pockets, etc. and anything probably right up to a combat mid-air. Heh heh.

EricV

[Mark Mc]

Eric,


Funny thing. Just the other day I was perusing an old magazine from the 60’s (don’t remember which one) over on the Outerzone website, and I found this add for MonoKote that I thought was timely, just 50 years late.  So I did a screen capture of it.  Just the opposite of your technique, and somewhat inline with what Larry’s been promoting.





Mark

[MikeyPratt]

Mike - I understand why you want the strength of the SLC for the open bays, but if I may be so bold to offer an alternative way to think about using it.

I too found it hard to keep the bubbles, wrinkles, etc out of the solid surfaces with SLC, especially down in the hot humid tropics.

The only reason to want the "strength" is for puncture resistance, right? Because plastic film really doesn't add any rigidity. So...

My solution is to put the SLC on FIRST and ONLY on the open bays, and only go about 1" over-size to the open bays to give it plenty of grip.

THEN treat the wing as if it's just a normal built up wing, and put on your 1 coat of full strength dope on the wood and film, then a 2nd and 3rd coat of thinned dope on ONLY the wood, (because the SLC doesn't absorb the dope and 1 coat is plenty) THEN put your silkspan/polyspan/doctor paper, whatever over top of that with some very thin dope and finish per usual.

It will easily hide the edge of where the SLC stops, and will give you a wing that will withstand your friends pens falling out of their pockets, etc. and anything probably right up to a combat mid-air. Heh heh.

EricV

Hi Eric,
Thanks for your suggestion, I do some of what you say except the fuselages are covered with carbon vial and then painted with dope.  So far it's worked out perfectly and looks really cool.  My covering and paint jobs have been really light with this process.  I know there is a lot of resistance to using dope because of the smell but it still works the best over the Minnwax type of finishes.  Also, the epoxy paints sprayed over the SLC film words quite well but that can get heavy if not used sparingly.  One other little trick I found is to attach a contrasting color plyspan over the base plyspan with a very light coat of spray adhesive to the back of the trim piece then cover with SLC (note: hold the adhesive at least 3' away from trim piece and let the over spray lightly fall onto the plyspan trim) them carefully place the trim in place and lightly rub the trim in place.  What you have in the end looks just like tissue covered F/F model with a lot less work.
Thanks Larry for inspiring me to try a different process.
Mikey

[Larry Renger]

Thanks to one and all for your interest and kind words. The original thread has 32000 views! 

Also thanks for the heads up on that old Monokote ad. Sometimes reinventing the wheel is a good thing. 

[Dane Martin]

Eric,


Funny thing. Just the other day I was perusing an old magazine from the 60’s (don’t remember which one) over on the Outerzone website, and I found this add for MonoKote that I thought was timely, just 50 years late.  So I did a screen capture of it.

Mark

I keep the little instruction sheet that came in a roll as inspiration in my building room!