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Building Tips and technical articles. => Paint and finishing => Topic started by: Chris Fretz on December 31, 2016, 08:11:40 AM
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So I was planning on covering a Tanager wing with Polyspan. First question is when referring to to putting a few coats of dope down, is that just clear dope? I think I can get a quart of Sig at a local hobby shop but I don't think they have Sig thinner. Assuming clear dope is what is ment by that.
I've only ever used Monokote before.
I watch Sparkys video on covering with Polyspan. He mentioned he wasn't going to use the Polyspan to cover the flaps. He said he was going to use silk or silkspan I can't remember, but why did he do that?
Do you cover the whole airplane in Polyspan or Silkspan? Or do you just paint the rest of the airplane?
Thanks for clearing that up.
Chris
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I guess I'll use butyrate.
I see a million different ways to do it so that just adds to the confusion.
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I see no one answered your question. I have completely covered planes with Poly-Span using dope. I don't know why Sparky used silk span on the flaps. I keep all the scrap pieces to cover every thing. Yes it takes patience and good pair of scissors and razor blades. I over lap the Poly just enough that at first you have a small seam, but after a few more coats of clear dope with talcum powder the seams will almost disappear. I don't use carbon because to me its not as strong as people say, my experience and it's expensive. Fiber glass gets heavy even though it goes over compound cures real well. The new material I'm playing with now will go over compound curves with heat and muscle. Once the plane is covered the material will get a rub down with a scouring pad and the rustoleum will be sprayed. It will not be a 20 point finish, but will be one you will have get right next to see the flaws. Rustoleum gloss paints are fuel proof if left to cure for several weeks and have a shine to them. Hopefully I will have more pictures as the wing is done as far as finish on the plane. Check out my post Secret weapon. H^^
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Chris,
as you noted, there are a myriad of ways to do this.
I do NOT use polyspan on the fuse or solid wood surfaces.
I use either silkspan or carbon veil.
The reason being, polyspan can have a tendancy to get heavy with dope in order to insure you have enough material to sand without getting fuzzies, which would then lead to more dope.
Silkspan and carbon can be sanded more aggresivly wihtout fear of that.
Some elect to just use the polyspan over the open bays out about 3/4 of an inch overlap onto the sheeting. then carbon on the rest.
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I see no one answered your question. I have completely covered planes with Poly-Span using dope. I don't know why Sparky used silk span on the flaps. I keep all the scrap pieces to cover every thing. Yes it takes patience and good pair of scissors and razor blades. I over lap the Poly just enough that at first you have a small seam, but after a few more coats of clear dope with talcum powder the seams will almost disappear. I don't use carbon because to me its not as strong as people say, my experience and it's expensive. Fiber glass gets heavy even though it goes over compound cures real well. The new material I'm playing with now will go over compound curves with heat and muscle. Once the plane is covered the material will get a rub down with a scouring pad and the rustoleum will be sprayed. It will not be a 20 point finish, but will be one you will have get right next to see the flaws. Rustoleum gloss paints are fuel proof if left to cure for several weeks and have a shine to them. Hopefully I will have more pictures as the wing is done as far as finish on the plane. Check out my post Secret weapon. H^^
Thanks for your reply Doc. I tried Rustoleum on a airplane last year. The airplane was heavy to begin with an seemed really heavy after the Rustoleum. Do you find Rustoleum to be heavy? Maybe I dumped too much on. How come you use Rustoleum over dope?
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Chris,
as you noted, there are a myriad of ways to do this.
I do NOT use polyspan on the fuse or solid wood surfaces.
I use either silkspan or carbon veil.
The reason being, polyspan can have a tendancy to get heavy with dope in order to insure you have enough material to sand without getting fuzzies, which would then lead to more dope.
Silkspan and carbon can be sanded more aggresivly wihtout fear of that.
Some elect to just use the polyspan over the open bays out about 3/4 of an inch overlap onto the sheeting. then carbon on the rest.
Hi Mark, I guess that's why Sparky only uses it on the wing. He did mention the fuzzies. Do you cover the wood surfaces for the strength or to cover up the grain rather than just pain it with dope? Where do you get silkspan at? Can you paint the silk or poly on with one brand of dope an top coat with a different brand?
Are you better off to cover the wing then install the wing or cover the wing after you install it?
Thanks
Chris
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I see Brodaks has silkspan, do you guys use medium or lite for solid wood surfaces?
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I have not used the Brodak silkspan but I have read reports from some who have used it and did not like it. From what I remember, it is not silkspan as we remember.
I use medium silkspan from Easy Built Models to cover bare wood. As was mentioned, it takes less dope to fill than polyspan and I like the way the silkspan sands smooth with a few coats of dope. The silkspan and dope on bare wood surfaces, such as flaps, stab, etc. add stiffness.
If I ever build a wing again with open bays I will cover it with Thermal Span. Thermal Span is the same as polyspan but with no grain. That is, it is as strong in the chord wise direction as span wise. It appears that the weave is a bit denser than polyspan so maybe it takes less dope to fill. Application and shrinking are identical to polyspan.
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Polyspan, silkspan, or carbon veil strengthens the structure even on solid wood, and it makes a hard(er) surface that'll be less likely to dent. It's probably also a lighter way to fill the grain.
Dope the wood with two or three coats, sand the wood's fuzzies off, then stick on the covering. The dope is the glue, and the wood has to be primed with it or things won't stick. Nitrate sticks better than buterate, and opinions vary on what's best. I've always used buterate clear throughout, BUT I haven't ever tried a for show-quality finish.
Enamel (like Rustoleum) is heavy, easy to put on too thick, and never gets as hard as laquer (dope). You'll never get a top-quality finish with it.
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Polyspan, silkspan, or carbon veil strengthens the structure even on solid wood, and it makes a hard(er) surface that'll be less likely to dent. It's probably also a lighter way to fill the grain.
Dope the wood with two or three coats, sand the wood's fuzzies off, then stick on the covering. The dope is the glue, and the wood has to be primed with it or things won't stick. Nitrate sticks better than buterate, and opinions vary on what's best. I've always used buterate clear throughout, BUT I haven't ever tried a for show-quality finish.
Enamel (like Rustoleum) is heavy, easy to put on too thick, and never gets as hard as laquer (dope). You'll never get a top-quality finish with it.
Ok sound like a plan, do you thin the dope during the first 3 coats? Do you thin it for the coats to stick down the poly or silkspan? I'm not looking for show quality, just something decent an better than monokote.
Thanks Tim.
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Ok sound like a plan, do you thin the dope during the first 3 coats? Do you thin it for the coats to stick down the poly or silkspan? I'm not looking for show quality, just something decent an better than monokote.
Thanks Tim.
You can get pretty darned good with Monocoat if you try. My "pretty decent" is well within what can be done with Monocoat, and maybe Rustoleum for trim colors.
Be that as it may -- yes, thin the dope for brushing and for sticking down. About 50-50 is good. Thin a lot more for spraying -- I'm not going to get into how much, because that's outside where I feel I have much expertise.
This one was covered in white 'coat on the wings, with Rustoleum on the fuselage and for trim. It did come out heavy, but I was heavy-handed both with the structure and with the spray-bomb.
(http://stunthanger.com/smf/building-techniques/fancherized-twister-build/?action=dlattach;attach=122653;image).
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You can get pretty darned good with Monocoat if you try. My "pretty decent" is well within what can be done with Monocoat, and maybe Rustoleum for trim colors.
Be that as it may -- yes, thin the dope for brushing and for sticking down. About 50-50 is good. Thin a lot more for spraying -- I'm not going to get into how much, because that's outside where I feel I have much expertise.
This one was covered in white 'coat on the wings, with Rustoleum on the fuselage and for trim. It did come out heavy, but I was heavy-handed both with the structure and with the spray-bomb.
(http://stunthanger.com/smf/building-techniques/fancherized-twister-build/?action=dlattach;attach=122653;image).
That's pretty nice looking for sure. Is that a profile genesis?
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That's pretty nice looking for sure. Is that a profile genesis?
More or less -- it's a Fancherized Twister with the fuse shape taken from Bob's Genesis article in FM.
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More or less -- it's a Fancherized Twister with the fuse shape taken from Bob's Genesis article in FM.
Creative! Where is the engine?
What's your thoughts on covering a wing an then using expoy to glue it in?
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Chris,
If you use Sig dope, then you should use Sig thinner too.
Duplicolor paint cans have an adjustable nozzle that shoots a knife edge pattern and an adjustable tip to spray vertical or horizontal, or in between. That makes it a lot easier than any other rattlecan brand to get good even coverage with fewer passes, so even the enamel might go on lighter than others. You can sweep faster and a little closer. It also dries extremely fast.
I prime first with NAPA DC-540. (DC=Dupicolor). But I had bad luck with the Duplicolor branded primer, it got hard as hell and impossible to sand, unlike the soft 540. You can sand it back down within an hour of applying it, but it won't fill deeper grain and dings. I also used the acrylic Laquer rather than enamel, but it's not fuelproof. So for your needs, I say go with the fuel resistant enamel and try to keep it light. Remember if you get small fingernail and bump & ding impressions in the balsa, a drop of water wiped on with a fingertip or damp paper towel will make them swell up and disappear for good.
This is just one more opinion to rattle around in your head. Try to cherry pick the answers and be consistent in the choices you line up to go forward with the job.My Twister came out very light, but I had M'koted wings. The last time I flew it(still experimenting with weight and balance), it was 41.7 oz with an aluminum spinner(like the one I showed you), fp.40, Eric tongue muffler, and metal tank. My new wing will have it back in action pretty soon. For my training needs, I'm sticking with M'kote wings for now.
Rusty
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Chris,
If you use Sig dope, then you should use Sig thinner too.
Duplicolor paint cans have an adjustable nozzle that shoots a knife edge pattern and an adjustable tip to spray vertical or horizontal, or in between. That makes it a lot easier than any other rattlecan brand to get good even coverage with fewer passes, so even the enamel might go on lighter than others. You can sweep faster and a little closer. It also dries extremely fast.
I prime first with NAPA DC-540. (DC=Dupicolor). But I had bad luck with the Duplicolor branded primer, it got hard as hell and impossible to sand, unlike the soft 540. You can sand it back down within an hour of applying it, but it won't fill deeper grain and dings. I also used the acrylic Laquer rather than enamel, but it's not fuelproof. So for your needs, I say go with the fuel resistant enamel and try to keep it light. Remember if you get small fingernail and bump & ding impressions in the balsa, a drop of water wiped on with a fingertip or damp paper towel will make them swell up and disappear for good.
This is just one more opinion to rattle around in your head. Try to cherry pick the answers and be consistent in the choices you line up to go forward with the job.My Twister came out very light, but I had M'koted wings. The last time I flew it(still experimenting with weight and balance), it was 41.7 oz with an aluminum spinner(like the one I showed you), fp.40, Eric tongue muffler, and metal tank. My new wing will have it back in action pretty soon. For my training needs, I'm sticking with M'kote wings for now.
Rusty
Thanks for the info Rusty, I always appreciate it!
I just ended up rushing to Brodaks Hobby shop an got some of his clear dope an thinner. Bought some silkspan too, ended up getting the lite for solid surfaces. I figured the medium would probably be better for open bays (at least my guess I dont know). Got a uniflow tank and a few other things. I can never leave that place without spending a fortune ::)
Ill see how this way goes, try something different for a change. ;D
Chris
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You're lucky to be that close to Brodaks.
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You're lucky to be that close to Brodaks.
Especially because of shipping.
Liner,
All I use now is silk on everything. IMHO, I think it's great stuff and I've tried other stuff.
I don't even put it on wet any more and I use CA to apply it. Figure that one out. LL~
True actually, check out the Gee Bee Z build and you will see dry silk applied with CA. Same with the ARGO 2's wings.
I just covered this GBR3 flap, both sides, in minutes. Tight as a drum.
Yes, I will use dope to fill the weave and the wood was given a few coats of dope also before the silk was applied.
Works for me.
Charles
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You're lucky to be that close to Brodaks.
It's nice to be close, I just wish I knew what I was doing ;)
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You'll know what you're doing pretty soon.
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Chris;
On my 3 profile planes, I installed the wing AFTER I monokoted them.
Left the center 3/8" bare wood for glue joint.
Carl
p.s. got something for you when I see you at Brodaks this summer.
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#Liner, you can't learn it all in one day, ask me how I know some time. To tell the truth I'm rediscovering some stuff I had forgotten. But as the saying goes, "When I quit learning is when they shove this carcus/body into the incinerator". H^^
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Chris;
On my 3 profile planes, I installed the wing AFTER I monokoted them.
Left the center 3/8" bare wood for glue joint.
Carl
p.s. got something for you when I see you at Brodaks this summer.
Ha ha what's that another 2nd place for me lol ;D
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He will probably move up a class so you won't make him looks so bad. LL~ LL~ Just stay with it and have patience. H^^
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So I was planning on covering a Tanager wing with Polyspan. First question is when referring to to putting a few coats of dope down, is that just clear dope? I think I can get a quart of Sig at a local hobby shop but I don't think they have Sig thinner. Assuming clear dope is what is ment by that.
I've only ever used Monokote before.
I watch Sparkys video on covering with Polyspan. He mentioned he wasn't going to use the Polyspan to cover the flaps. He said he was going to use silk or silkspan I can't remember, but why did he do that?
Do you cover the whole airplane in Polyspan or Silkspan? Or do you just paint the rest of the airplane?
Thanks for clearing that up.
Chris
Purchase Brodak's book on "Painting & Finishing Your Airplane" for $7.50. This gives you the fundamentals to prep the wood and cover the plane using dope and silkspan, as well as priming, painting and clearing. I used it to get started a few years ago and it gave me a jump start rather than asking questions where you will get too many replies with too many techniques that differ. I have also been using a good quality medium silkspan from the "Easy Built Models" web site, comes in rolls. I double cover open bays of wings on large planes (60 inch spans) but it works great on solid wood surfaces. Good luck!
Don
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Purchase Brodak's book on "Painting & Finishing Your Airplane" for $7.50. This gives you the fundamentals to prep the wood and cover the plane using dope and silkspan, as well as priming, painting and clearing. I used it to get started a few years ago and it gave me a jump start rather than asking questions where you will get too many replies with too many techniques that differ. I have also been using a good quality medium silkspan from the "Easy Built Models" web site, comes in rolls. I double cover open bays of wings on large planes (60 inch spans) but it works great on solid wood surfaces. Good luck!
Don
That's a pretty good idea, thanks! I just picked it up.
Chris
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Creative! Where is the engine?
What's your thoughts on covering a wing an then using expoy to glue it in?
That picture was taken before final assembly. The engine is a 46LA, which is now on the plane.
I always wanted nice fillets, and I got them by building the wing, covering the center section with silkspan, gluing it into the fuse, making the fillet, painting the fuse, and then finally ironing on 'coat. Structurally, I have no problem with doing the whole thing with 'coat -- I even know that it's possible to do a nice job covering a profile fuselage with 'coat, because a member of the Fireballs does it. I just haven't gotten the courage to try it myself.
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Chris
nothing like that at all. Hoping to learn inverted flying and then at representation of the full pattern for Brodaks.
Ithink you will like it..........
Carl
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If I ever build a wing again with open bays I will cover it with Thermal Span. Thermal Span is the same as polyspan but with no grain. That is, it is as strong in the chord wise direction as span wise. It appears that the weave is a bit denser than polyspan so maybe it takes less dope to fill. Application and shrinking are identical to polyspan.
What is source for "Thermal Span" ?
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I wonder if Thermal Span is still available. I did a search for the company (Harris Design) but found nothing. They had a website at one time but I can't find it now.
Here is an e-mail address I had some time ago. If it is still good it might get you to someone who knows more: jonharris2@comcast.net
Maybe you will have better luck. This is the last info I had for an address but no phone number.
Harris Design
5835 Griffith Dr.
Brighton, MI 48116
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Especially because of shipping.
Liner,
All I use now is silk on everything. IMHO, I think it's great stuff and I've tried other stuff.
I don't even put it on wet any more and I use CA to apply it. Figure that one out. LL~
True actually, check out the Gee Bee Z build and you will see dry silk applied with CA. Same with the ARGO 2's wings.
I just covered this GBR3 flap, both sides, in minutes. Tight as a drum.
Yes, I will use dope to fill the weave and the wood was given a few coats of dope also before the silk was applied.
Works for me.
Charles
Charles,
Have you found a reasonable source for your silk?
BC
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Charles,
Have you found a reasonable source for your silk?
BC
BC,
I was given this Vendor by another modeler some time back.
http://www.dharmatrading.com/fabric/silk/silk-habotai-5mm.html
This link should be the page of what I use.
5mm, 36" 2.99 per yd. I buy 15.00 worth at a time.
I order it right over the phone.
CB