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Author Topic: Silkspan (yes -- silkspan) fuzzies?!?  (Read 1699 times)

Offline Tim Wescott

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Silkspan (yes -- silkspan) fuzzies?!?
« on: April 05, 2020, 04:55:41 PM »
So, on the Atlantis cowl I've filled a bunch of holes (half a dozen needle valve holes, exhaust hole, muffler mount holes, and a pipe tunnel), mounted a scoop where the engine used to stick out, and basically taken the hacked-up experimental cowl that Paul left me and tried to make it pretty.

With all the patches there's some ridges in the final product.  I got quite aggressive about trying to smooth things out, and got fairly deep into the silkspan in places.  In some of those, I now have persistent fuzzies.

Now repeated coats of dope and light sanding doesn't seem to be dealing with the fuzzies -- the dang things are just persisting.

So -- does this make sense to anyone?  I've been using 220 grit garnet paper for fast cutting; should I change to a finer grit?  Is there something else I should be doing?
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Offline Avaiojet

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #1 on: April 05, 2020, 05:32:57 PM »
I'd add some high build primer or a skim of auto putty to that area and then some.

Possibly a drop of CA with a quick finger rub to knock down the fuzzies prier to the high build primer.

Don't really press when you sand. Or, 320 takes a bit longer but you might want to use 320.

Gotta get that silk span under primer or your paint might bring it back up?

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Offline Tim Wescott

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #2 on: April 07, 2020, 10:07:38 AM »
Bump.  Touching up just the bumpy parts and just knocking down the fuzzies seems to be very slowly working -- am I just doomed to some big bumps here?
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Offline Avaiojet

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #3 on: April 07, 2020, 10:23:51 AM »
Quote
Bump.  Touching up just the bumpy parts and just knocking down the fuzzies seems to be very slowly working -- am I just doomed to some big bumps here?

You have two choices.

You have highs and low areas.

Bring up the high or sand down the lows. How high can these bumps be?

Board sand the thing till the bumps are gone. Apply a few coats of dope or Deft Wood Sealer Lacquer. Scratch that up then cover the exposed area with a piece of silk then add some more coats of clear. Build the clear up and feather the edges of the silk. The silk is under clear by now.

Kill the shine with some 320 then prime the thing with a high build primer. Then prime it again.

After this, it's a scuff and auto body filler to arrive at the given shape and you shouldn't need much of it. If needed at all.

Good luck.

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Offline Tim Wescott

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #4 on: April 07, 2020, 10:44:52 AM »
You have two choices.

You have highs and low areas.

Bring up the high or sand down the lows. How high can these bumps be?

Board sand the thing till the bumps are gone. Apply a few coats of dope or Deft Wood Sealer Lacquer. Scratch that up then cover the exposed area with a piece of silk then add some more coats of clear. Build the clear up and feather the edges of the silk. The silk is under clear by now.

Kill the shine with some 320 then prime the thing with a high build primer. Then prime it again.

After this, it's a scuff and auto body filler to arrive at the given shape and you shouldn't need much of it. If needed at all.

Good luck.

I'm really, really hoping to get an answer from someone who's actually entered a contest and scored well in appearance judging, with a plane finished in dope.
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Offline Avaiojet

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #5 on: April 07, 2020, 11:04:58 AM »
I'm really, really hoping to get an answer from someone who's actually entered a contest and scored well in appearance judging, with a plane finished in dope.

There's plenty of modelers who have great building and finishing skills who don't enter contests.

At least I do photo builds, and list the products I use, right to the finish. Plus I put up photos of my finished "hanger queens." All for sale on ebay BTW, I'm going Electric.

I used to paint R/C pattern ships for guys who went to contests and passed the finish off as theirs.

Are there people in CL who do the same? BOM?

What I told you is solid help. Eventually you'll stop using dope. Tons have already stopped.

You're issues are model building 101 stuff. You've been around a long time?
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Offline Randy Powell

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #6 on: April 07, 2020, 12:47:36 PM »
Tim,

As a general rule with silkspan and dope is, if you get "fuzzies", put on more dope. I tend to block sand. You can use CA in places where you sanded through the silkspan or created other issues, but generally speaking, sand and put more dope on.

Looks like it's coming along fairly well.

Oh, you can search on this site for the Phil Granderson method of finishing. Phil is a master with many, many concours level finishes. And he doesn't use any filler coat.  it isn't just about the appearance, it's also about the weight. Amazing what you can do if you don't care how heavy it is.
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Offline Avaiojet

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #7 on: April 07, 2020, 01:23:18 PM »
Quote
And he doesn't use any filler coat.

Exactly what is a "filler coat?"
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Offline Howard Rush

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #8 on: April 07, 2020, 01:38:00 PM »
http://flyinglines.org/ptg.finishing.html  I was just looking that up for my personal use. 

I think I’d sand off the bumps oblivious of fuzzies, then deal with fuzzies with dope and 1000 paper.  You will have some places with silkspan on them and some without. If you want, you can put silkspan patches on the bare spots.  The quickest-to-finish way of doing that is to tear, rather than cut, the patch from a piece of silkspan. The edge is thus kinda tapered and easier to fair in.
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Offline Randy Powell

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #9 on: April 07, 2020, 01:51:12 PM »
Don't know when this was from, but Phil told me is discontinued using filler coats (talc and clear) and just went to using successive coats of unthinned non-taunting clear. He felt he got the same outcome and it was lighter.

Everybody has their own system. I've used urethanes, enamels, lacquers, water based acrylics and catalyzed polyurethanes. Getting a great finish isn't that hard, but getting a great finish that is also light can be quite difficult.
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Offline Howard Rush

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #10 on: April 07, 2020, 08:17:20 PM »
Don't know when this was from, but Phil told me is discontinued using filler coats (talc and clear) and just went to using successive coats of unthinned non-taunting clear. He felt he got the same outcome and it was lighter.

I use his talc method.  You blow on a plethora of talc and end up with a giant blob of talc that approximates the shape of an airplane.  Then you just carve an airplane out of it.  Works a treat.
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Offline Randy Powell

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #11 on: April 08, 2020, 11:53:38 AM »
I use his talc method.  You blow on a plethora of talc and end up with a giant blob of talc that approximates the shape of an airplane.  Then you just carve an airplane out of it.  Works a treat.

Well, that's the general idea. But I do it with just clear dope.  ;D
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Offline John Leidle

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #12 on: April 18, 2020, 10:06:31 AM »
   Hi Tim ,
  Nice to see you using paint.... my thoughts are find someone that knows what he's doing ,  stick with that person for the most part because of the so many ideas. I tend to build a substrate somewhat as Randy does so I suggest you follow his lead he won't direct you into any of the trick Sh!#*t that doesn't work . Randy was doing this before I got in the hobby.
          John L.

Offline Avaiojet

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #13 on: April 18, 2020, 12:31:29 PM »
   Hi Tim ,
  Nice to see you using paint.... my thoughts are find someone that knows what he's doing ,  stick with that person for the most part because of the so many ideas. I tend to build a substrate somewhat as Randy does so I suggest you follow his lead he won't direct you into any of the trick Sh!#*t that doesn't work . Randy was doing this before I got in the hobby.
          John L.

In a perfect world this suggestion would be great. However the world isn't perfect.

Here's the thing.

Many modelers, for whatever the reason, choose NOT to use spray equipment. I can think of four reasons right off the bat, no pun for China, and none of the reasons have to do with quality in finish.

So, modelers have to decide or make a decision on the process they elect to use in finishing. Paint by brush, aerosol cans or spray equipment. Or a combination of all?

AND, as it was mentioned, plenty of guys do this plenty of different ways.

So, once a decision is made, they can zero in on a step by step process that suits their needs.

I've used professional spray equipment my whole life and I've used professional spray equipment to finish many models, yet I now elect to use only aerosol cans to finish my models. Well, I do use an airbrush for my painted canopies.

I've made my choice.

So, choose wisely.







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If you're Trolled, you know you're doing something right.  Alpha Mike Foxtrot. "No one has ever made a difference by being like everyone else."  Marcus Cordeiro, The "Mark of Excellence," you will not be forgotten. "No amount of evidence will ever persuade an idiot."- Mark Twain. I look at the Forum as a place to contribute and make friends, some view it as a Realm where they could be King.   Proverb 11.9  "With his mouth the Godless destroys his neighbor..."  "Perhaps the greatest challenge in modeling is to build a competitive control line stunter that looks like a real airplane." David McCellan, 1980.

Offline Howard Rush

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #14 on: April 18, 2020, 02:34:12 PM »
Maybe it’s a Northwest thing, but we use brushed-on dope and sandpaper until we’re past the bumpy and fuzzy stages.
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Offline Howard Rush

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #15 on: April 18, 2020, 02:40:09 PM »
Randy was doing this before I got in the hobby.

And he knows every finishing method.
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Offline Jim Hoffman

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #16 on: April 18, 2020, 03:44:02 PM »
I too brush dope from the wood up including the filler coats.  I don't spray until the polar grey blocking coats.  I started using a large 2 inch brush a few years ago.  This was a huge time saver and has produced the base for some nice finishes

Offline Tim Wescott

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #17 on: April 18, 2020, 05:45:04 PM »
Thank you all -- just so you know, I gave up.  I just stripped the whole cowl back to the bare wood (it's even bare-er than before, because I took of most of the last of Paul's undercoats).

I'm ordering some KBS Diamond Clear per Phil's directions, and will be following his instructions from there.
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Offline Dan McEntee

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #18 on: April 18, 2020, 09:14:58 PM »
   See as it's a cowl from a well used airplane, there may still be some oil in the balsa? Apply some heat from a monokote heat gun carefully and see what if any, boils out. Heat it then wipe off what boils out with a paper towel and some acetone. If you used a lot of CA in your reconstruction, that won't soak up any dope. The garnet paper probably is causing you some grief also, even 220 grit,. Ditch that for some better stuff, for what you were trying to do, you didn't need to cut fast, just knock off the top.  But now that you got it all stripped, I would still trying heating the problem areas to make sure there is no oil soaking. Then try your favorite method.
  I don't know about this KBS Diamond stuff, as I recall mixed results from people. I read the description that Phil G wrote in Tight Lines that Howard posted, and using it as a base for sealing the wood was surprising, and that dope adhered to it, but his results showed it worked OK. good luck with it and keep us posted.
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Offline Howard Rush

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #19 on: April 19, 2020, 02:55:21 AM »
I haven't used the KBS stuff.  That's a recent change to PTG's instructions.   
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Offline Tim Wescott

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #20 on: April 19, 2020, 04:41:18 PM »
Hey Dan!

Thanks for the tip about heating -- there's not a problem with Paul's wood, at least on the outside of the cowl, but some of the wood that I had on there had a few coats of dope, and apparently that wasn't enough.  It felt like wax, and the dope didn't seem to want to fully 'set' on it.  I wasn't fully satisfied with the adhesion I was getting -- so I'll see if I can force some out before I start in on this project again.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Dan McEntee

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #21 on: April 19, 2020, 10:20:00 PM »
Hey Dan!

Thanks for the tip about heating -- there's not a problem with Paul's wood, at least on the outside of the cowl, but some of the wood that I had on there had a few coats of dope, and apparently that wasn't enough.  It felt like wax, and the dope didn't seem to want to fully 'set' on it.  I wasn't fully satisfied with the adhesion I was getting -- so I'll see if I can force some out before I start in on this project again.

   There have been a few threads on "de-oiling"  balsa on an old model. Most often mentioned is the K2R Spot Remover. It's a spray on solvent that has some sort of powder with it that lifts the oil and the powder absorbs it. It works OK but the cans are small and expensive. Some one else on the forum suggested the monokote gun, and when I decided to recover my well used and much flown SIG Primary Force, I used it as a test for all the methods I had read about.  Out of all the methods, the heat gun was the best. It will get 99% of the oil out. You know you are finished when no more oil rises out of the wood. Do it in steps, heat, wipe off, heat again, wipe off, just follow your nose. It raises the grain a bit also but you will be sanding it again anyway. I had no trouble with getting Monokote to adhere to the wood after I was finished, but on potential trouble spots on the nose I brushed on some SIG Stix-It just in case. On your cowling, make the first few coats of dope pretty thin and let the thinner help flush out anything else. I think it will work well for you
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« Last Edit: April 20, 2020, 09:26:51 AM by Dan McEntee »
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Offline Howard Rush

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #22 on: April 19, 2020, 11:40:10 PM »
I think the powder in K2R is colloidal silica. Cab-o-sil might do the same thing. I may have used it, but I forget. Acoustic stunt seems so long ago.
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Offline Tim Wescott

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #23 on: May 14, 2020, 02:02:08 PM »
HAH!  I think we all completely misdiagnosed the problem.

I stripped it down to bare balsa all around, even taking off the tissue Paul had on there.  In the process the really oily wood was feeling like wood again instead of a wax model of a hunk of balsa.  So I covered it with tissue & started building up coats.

Even while being very careful, all the spots that were causing me grief before are causing me grief now -- and, after Dan's comments about oil, I notice that they're all places where you'd expect oil to seep out of wood after a good long soak -- and all the new wood that's on it is just fine.  So I think that what's happening is that each time I put a coat of dope on the thing the thinner is drawing out a bit of oil from underneath, that's making the top surface bumpy.

I'm just declaring it done. 

If I get tired of it at some point I'll strip it again, then heat it (or maybe just simmer it in methanol for half an hour, it's really oily), then start over.  Or I'll make a new one from scratch, because it doesn't quite match the fuselage.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline Dan McEntee

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #24 on: May 14, 2020, 02:39:44 PM »
   One more trick to try for your log book if you do refinish it again. I have heard stories of Bill Werwage having flown the original Ares so much that the nose got very oil soaked and needed attention, so over the winter, the gentleman who was his mentor at the time suggested soaking the entire nose in acetone until the old finish came off and all the oil leached out. He them just had to touch up some glue joints, do some sanding and then refinished the nose. How true this is, I do not know, but soaking a cowling in acetone would be easy. I would soak it down in a pan then put it in a sealed bag or container that the acetone wouldn't attack.  I'm convinced after all these years that you can not make the nose of any stunter completely fuel proof. I still advocate for the heat gun method as the quickest, most complete and maybe even safest.
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Offline Tim Wescott

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Re: Silkspan (yes -- silkspan) fuzzies?!?
« Reply #25 on: May 14, 2020, 02:55:56 PM »
   One more trick to try for your log book if you do refinish it again. I have heard stories of Bill Werwage having flown the original Ares so much that the nose got very oil soaked and needed attention, so over the winter, the gentleman who was his mentor at the time suggested soaking the entire nose in acetone until the old finish came off and all the oil leached out. He them just had to touch up some glue joints, do some sanding and then refinished the nose. How true this is, I do not know, but soaking a cowling in acetone would be easy. I would soak it down in a pan then put it in a sealed bag or container that the acetone wouldn't attack.  I'm convinced after all these years that you can not make the nose of any stunter completely fuel proof. I still advocate for the heat gun method as the quickest, most complete and maybe even safest.
  Type at you later,
   Dan McEntee

I think though, that if the thing were glued up with Ambroid that you'd end up with all the original wood bits, completely unglued -- that's why I would try methanol (or denatured alcohol).

I know that those few times I've hung out with indoor freeflight types, I noticed that they all had a bottle of Duco cement heavily (like, 1:3) thinned with acetone.  They would use this for trim adjustments, because just a drop would thin the glue joints (also Duco) holding the airplane together.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.


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