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Author Topic: Silkspaning balsa sheeted Foam cores???  (Read 2003 times)

Offline Ron Varnas

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Silkspaning balsa sheeted Foam cores???
« on: January 27, 2011, 02:40:02 AM »
Hi all,

just like a few 'do's & dont's in regards to silkspaning a sheeted balsa foam core wing?
i know theres pitfalls if the 'dope' gets thru but there must be some tried & proven methods
over the years, as the foamies werent always finished in monkote, etc
or had the balsa sheeting filled with epoxy prior to base coats? i think the epoxy fill is great
'if'one knows how to do 'it' properly, id rather take a chance being carefull with dope) :-\
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Offline Leester

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #1 on: January 27, 2011, 04:01:31 AM »
If you use epoxy to attach your sheeting to the cores you shouldn't have any problems.
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Offline Balsa Butcher

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #2 on: January 27, 2011, 07:35:25 AM »
Attaching balsa skins with epoxy is a good technique and one I currently use. Still, I have done quite a few foam wing using the 3M spray adhesive. After attaching the balsa sheeting I have used dope and silkspan finishes on all of them. Never had any problems as far as the dope attacking the foam through the wood. Some I did in the 90's are still flying today and look great.  8)
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Offline David Shad

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #3 on: January 27, 2011, 09:11:19 AM »
I agree the guys...after probably 100 sets of foam wings skinned with balsa...then painting...either with dope or other I have never had an issue with dope or paint attacking the foam...I usually do silkspan as a substrate doping
before and after...the results are good. 
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Offline Randy Ryan

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #4 on: January 28, 2011, 07:06:29 AM »
Quote from: David Shad on January 27, 2011, 09:11:19 AM
I agree the guys...after probably 100 sets of foam wings skinned with balsa...then painting...either with dope or other I have never had an issue with dope or paint attacking the foam...I usually do silkspan as a substrate doping
before and after...the results are good. 



This is all assuming of course that all the fits are good so there are no gaps to allow dope to get under the balsa. Be careful too of filling gaps, make sure if you do that the fllier isn't porous. Best bet........... no gaps to fill.
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Online Bill Hummel

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #5 on: January 28, 2011, 07:15:04 AM »
Hi, Ron, like most of the other guys, I've had little problems over the years.
1. I like epoxy resin to attach the balsa skins
2. Gentle sanding, then 3-4 coats of dope, 50/50, non-taughtening
3. Medium or heavy silkspan applied damp, trying to minimize wrinkles
4. Another 3-4 coats of 50/50 dope to seal the silkspan
No worries, nice wings, seem to last "almost" forever!
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Offline Larry Renger

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #6 on: January 28, 2011, 11:27:25 AM »
Yup, good to the first drop!  >:D
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Offline Frank Imbriaco

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #7 on: January 28, 2011, 06:39:01 PM »
Are  foam wing flaps  more prone to warping with dope & silkspan ?
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Offline Bill Little

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #8 on: January 28, 2011, 07:47:42 PM »
Quote from: Frank Imbriaco on January 28, 2011, 06:39:01 PM
Are  foam wing flaps  more prone to warping with dope & silkspan ?

Not, IMHO, Frank.  Others may have had a different outcome. ???

Big Bear
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Offline Ron Varnas

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #9 on: January 29, 2011, 07:49:40 AM »
Hi Bill H)

what dope are we talking about here
Nitrate or Butrayte ?

Ron
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RJV Melb. Australia

Online Bill Hummel

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #10 on: January 29, 2011, 09:10:46 AM »
Ron, after several repair "disasters", I use butyrate now for everything, start to finish.  Randolph, Brodak, and until recently, Sig all work well for the job.
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Offline john e. holliday

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #11 on: January 29, 2011, 10:12:29 AM »
I used to use Nitrate and then go to Butyrate.  Now I go Butyrate from day one as I had a quart jar of clear that the label(masking tape) fell off.  Butyrate goes over Nitrate.  Nitrate will not go over Butyrate with a great big mess.  As far as doping the sheet balsa over a foam wing I have not had any problems with the dope bleeding thru the 1/16th sheet wood.  I do use contact cement to put the sheets on the foam. H^^
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Offline Bill Little

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #12 on: January 29, 2011, 01:11:03 PM »
Quote from: Bill Hummel on January 29, 2011, 09:10:46 AM
Ron, after several repair "disasters", I use butyrate now for everything, start to finish.  Randolph, Brodak, and until recently, Sig all work well for the job.

Hi Bill,

What happened??

Bill
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Offline Ron Varnas

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #13 on: January 30, 2011, 06:20:13 AM »
Hi again Bill H)

with the Randolph is it only one type of dope they supply or their
are various types & whats the thinning ratio ( talking the silksp/ over sheeted cores) 50/50 ?
whats with the until recently with the 'sig' have they discountinued the dope range?
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RJV Melb. Australia

Online Bill Hummel

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #14 on: January 30, 2011, 11:32:32 AM »
Hi, Ron, Ranldolph makes a variety of dopes; I use the non -taughtening to secure the silkspan.
With a "solid" sheeted wing, I use this right up to color dope, as no need to shrink very much.
Randolph also makes a standard "shrinking" dope, which I've used with success on built-up
wings.  The mix with thinner is "about 50/50 or so", really what works well to brush it on. I
don't believe the mix is critical at all. Info is that Sig is no longer supplying dope, don't know if
this is permanent or temporary? 
Bill L:  sent you an e-mail...
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Offline Don Hutchinson AMA5402

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Re: Silkspaning balsa sheeted Foam cores???
« Reply #15 on: January 30, 2011, 04:24:38 PM »
Ron- Go to Randolph Aircraft Products and in the products window you will see all the different types of nitrate and butyrate dopes, thinners, retarders plus all the color dope info you would like. The Randolph colors are a non-tautenjng formulation. Good stuff and reasonably priced.
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