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Building Tips and technical articles. => Paint and finishing => Topic started by: Motorman on November 16, 2019, 06:06:47 PM
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I think SGM may be Super Gas Model, I thought it was the heaviest one?
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I've been searching through some old finishing posts and I see that finishing bare balsa with silkspan is maybe the best way to go, for me anyway. Which is lighter 00 or 000 and where do you get it?
Thanks,
Motorman 8)
Why do you feel,
"silkspan is maybe the best way to go, for me anyway." ???
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I just checked, Sig carries OO, and Brodak carries "light" and "medium" (which is probably OO and GM). There are probably enough older modelers "retiring" that if the family members know what they have, it'll be up on eBay -- but maybe not at decent prices.
Search here on "doctor paper" and "exam paper". There's a specific line of doctor's office exam-table paper that's supposed to work well as a silkspan substitute.
If you're covering open bays with tissue, you want to use Esaki -- which, unfortunately, is out of production as of this year :(. For sheeted surfaces, if I used tissue I'd use domestic. I'd try to apply it damp on sheeted surfaces, but the stuff doesn't have much wet strength (unlike silkspan or Esaki) so I'd be very careful, and I'd be ready to back off and apply it dry to simple curves.
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Sig Medium has always been my favorite for our models, whether it be over solid wood or open bays. As far as the grades go I've always used either Sig or the K&S brand as my reference. I don't know what OOO would equate to but my understanding is that K&S "OO" is their lightest stuff, equal to Sig "Light", and primarily intended for Free Flight models and the like. From there, the K&S "GM" equals Sig "Medium" and their "SGM" equals Sig "Heavy".
As a side note, I'd stay away from Brodak's so-called silkspan. I tried a half dozen different packages of it a few years ago and the material was closer to a brown paper bag than silkspan, very heavy, difficult to work with, and it didn't take dope worth a damn. It didn't even work well over solid wood, after fighting it for a while I ended up just throwing it all away.
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Someone that makes better finishes than me said it comes out better and lighter than CF veil which is about $60 a plane.
The whole plane is sheeted so no open bays.
They say the sig paper is different today and the doctor paper is the thick stuff so maybe J-tissue might be easier to find at least.
Motorman 8)
You haven't researched the exam table paper enough, because it has been discussed in deep detail on here. There are two different weights of the exam table paper made by TIDI. It was compared for weight to known existing sample of new old stock K&S silk span and was spot on the same, and the results posted in a couple of threads. It handled the same even wet. Other manufacturers produce like materials. There are about 50 different types of exam table paper if you check out their websites. All you have to do is search out the several threads on the subject.
If you haven't checked out the current SIG offerings, why would you trust "They?" They might be wrong?
Type at you later,
Dan McEntee
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Wingspan of the model?
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As a side note, I'd stay away from Brodak's so-called silkspan. I tried a half dozen different packages of it a few years ago and the material was closer to a brown paper bag than silkspan, very heavy, difficult to work with, and it didn't take dope worth a damn. It didn't even work well over solid wood, after fighting it for a while I ended up just throwing it all away.
I have purchased Medium silkspan from Brodak in the last two years. What I got was perfectly white. It has very little wet strength and you must be careful to get the smoother side up. I have used the Brodak medium silkspan on a couple of wingtips. If you get the smoother side up it will be baby butt smooth after a few coats of clear and sanding down a coat of Brodak white primer.
I got the rougher side up on one wingtip and after several coats of clear it is still rough. I haven't put the white primer on the rough silkspan yet, but I'm hoping that it will get baby butt smooth before I'm done.
Joe Ed Pederson
Cuba, MO
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I have purchased Medium silkspan from Brodak in the last two years. What I got was perfectly white. It has very little wet strength and you must be careful to get the smoother side up. I have used the Brodak medium silkspan on a couple of wingtips. If you get the smoother side up it will be baby butt smooth after a few coats of clear and sanding down a coat of Brodak white primer.
I got the rougher side up on one wingtip and after several coats of clear it is still rough. I haven't put the white primer on the rough silkspan yet, but I'm hoping that it will get baby butt smooth before I'm done.
Joe Ed Pederson
Cuba, MO
I fixed all those problems by throwing mine in the trash. ;D
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Well, the OO is what you wanted to know about. But I mis-spoke about SGM. George is correct. Here is a cut out from one of my boxes of K&S Silk Span. H^^
I just checked some old catalogs from way back when and that is what they listed, 00+light, GM+ medium, and SGM= heavy. I think that is all weights that was ever produced. anything else might have been some kind of domestic tissue or bamboo paper.. I think I have some of that also downstairs.
Type at you later,
Dan McEntee
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I just checked some old catalogs from way back when and that is what they listed, 00+light, GM+ medium, and SGM= heavy. I think that is all weights that was ever produced. anything else might have been some kind of domestic tissue or bamboo paper.. I think I have some of that also downstairs.
GM = Gas Model
SGM - Super Gas Model
I have heard people claim to have, or previously had, 0000 silkspan but I have never seen a sample of it. I am more-or-less decided to use carbon veil from here on out, since it's much less prone to damage, but I always used 00 on solid surface, and GM on open bays.
Brett
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The problem with silkspan paper or silk fabric is the amount of dope required to fill it. On bare wood either will cover the grain and provide a good substrate with enough dope and the grain won't come through later. The heaver the grade of either the more dope as they both soak up dope to fill (also dope still soaks into the bare wood below). This is were the carbon veil and polyspan do better as they don't soak in the dope.
Light weight fiberglass cloth 1/2oz or 3/4oz does the same thing as the CV or polyspan when attached with dope. 1/2oz is equivalent to 5mm silk (very light weight like the old K& S) and 3/4oz to 8mm. I have been told that using the 3/4oz is actually lighter because the glass fiber is the same weight as the 1/2oz just there are more of them per sq in, and needs less dope it fill). Nitrate would attach very strong but I have used butyrate and never had it pull away. FG goes around curves nicely and can be stretched very tight. Bottom line is that dope is weight and as captain obvious would say - more dope more weight.
Best, DennisT
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MM,
The dope and filler will fill the grain but as the dope shrinks will allow the grain to pop out after a few years. Any of the coverings discussed will do the job of covering the grain, some just weigh a little more.
Best, DennisT
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So are you guys telling me that it's better to use CV or glass cloth than it is to just fill the grain with nitrate dope and zinc sterate powder?
Or silk or silkspan. You will wind up much heavier if you try to fill the grain directly, if you put on enough of it to have it be stable over time.
Brett