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Author Topic: 1 more time........please  (Read 1811 times)

Offline Russ Danneman

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1 more time........please
« on: September 21, 2009, 03:08:12 PM »
i know it's been covered and covered(no pun) but i am a monokoter who wants to give silkspan a try. i have read all the post but the more i read the more i get confused!  e.g. which dope nitrate, Butyrate,taunting,non-taunting,mop and glow etc.what is the best way for a rookie to go at it? thanks for the advice! russ
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Offline Allan Perret

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Re: 1 more time........please
« Reply #1 on: September 21, 2009, 03:30:00 PM »
For your first attempt keep it simple and use just butyrate, non tautening if there is a choice.
Sand framework with about 220 grit.  Then brush on 2 or 3 coats of 50/50 thinned on perimeter of framework.  Sand again very lightly just to knock down the nubs, you dont want to remove any of the dope on the surface.  Cut your silkspan at least 1" (2 or 3 is better) bigger than surface all the way around, you need this to pull out the wrinkles before you dope it down.  Then dampen silkspan, lay on wing and brush thru the silkspan around the perimeter only with 75/25 thinned (some use straight thinner for this step) to attach silkspan to structure.  Then go back to 50/50 mixture for fill coats to build up substrate.  It will take 2~3 coats to start to fill the weave of the span, maybe 5~6 to fill it completly.  You can add talc or cornstarch to fill coats to help it fill.  About a heaping teaspoon to a pint of thinned dope mixture, or as much as will stay in suspension.  
This is the way I like to dampen the silkspan.   Lay a large bath towel on workbench,  put silkspan on one side of towel, spray it with water till its soaked pretty good, then fold other side of towel over on top of the silkspan, then press on the towel to blot out the excess water.  If you get all the wrinkles out before you start doping around the edges, it will be tite when the water dries.  
« Last Edit: September 21, 2009, 03:50:20 PM by Allan Perret »
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Offline Randy Powell

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Re: 1 more time........please
« Reply #2 on: September 21, 2009, 04:12:59 PM »
Might check out Phil Granderson's article in Model Aviation on finishing. Very simple and straight forward. Phil's one of the best.
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Online Matt Colan

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Re: 1 more time........please
« Reply #3 on: September 21, 2009, 04:21:30 PM »
For a first attempt, use butyrate dope, I use Brodak.
What I do is sand all bare wood smooth with either 220 or 320.  Then I apply one coat of Brodak clear to the wood, thinned somewhere around 50/50.  After the first coat of clear is dry, the wood should feel rough to the touch, that is because the clear swelled the wood.  I "knock the fuzz off" with 320 (this makes the wood smooth again) and then I apply a second coat of clear.  Again the wood should again feel rough to the touch.  The wood swelled with the second coat of clear, but less than the first.  Once again knock the fuzz off with 320.  Keep doing this until the wood is smooth after applying the clear without sanding.  This gives you a good base and will your finish will become light.
Next dampen the silkspan.  Cut the silkspan bigger than you need to.  What I do to wet the silkspan is lay it on a towel, and spray it with water until it is good and wet.  Then i take the other half of the towel and dry it out with it.  Now the silkspan is damp.  Lay the silkspan on the wood that you are attaching it to.  If the wood is a solid surface, brush on clear from the middle out, as it will help to somewhat prevent wrinkles.  Make sure you get clear on ALL the silkspan.  After the silkspan is on the wood, I take a paper towel, and gently rub it down to get rid of the wrinkles.  Now if you are attaching the silkspan on an open bay area, go along the perimeter of the wood, don't go into the open bays.
When the silkspan is dry, you can start to build up your substrate with clear.  I typically go up to 6-7 coats of clear before I spray on a coat of auto primer, then sand it down, since auto primer is very heavy.  I typically put on 2 coats of primer, before color.  Now for my Oriental Plus, I think I"m going to spray Silver as my primer because I'm planning to use coolors that don't cover very well (white, and red.  Yellows and oranges also don't cover very well.).

Hope this helps you out and good luck H^^
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Offline Clint Ormosen

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Re: 1 more time........please
« Reply #4 on: September 22, 2009, 02:32:55 AM »
Sorry, but I have to be a Buttinski here. I would try to avoid fillers like talc and cornstarch in the dope. At least until you're more familiar with using it. Those fillers can cause unwanted adhesion problems. Just use straight dope to fill the silkspan. It's probably the difference of only one coat anyway.
 And before anyone jumps all over me for this, you'll notice I said "can" cause problems, not "will" cause problems. Because it can.
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Offline Russ Danneman

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Re: 1 more time........please
« Reply #5 on: September 22, 2009, 10:43:23 AM »
thanks guys,thats what i want a simple way to start for a first timer!
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Offline Randy Powell

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Re: 1 more time........please
« Reply #6 on: September 22, 2009, 03:45:08 PM »
Clint,

Heck, I used fillers for years and have come full circle. I don't really use fillercoat anymore. Just un-thinned, non-taunting butyrate. 3 or 4 coats of that molasses and the grain is pretty much filled. It sands easily and you can get a very smooth base. And as you note, adhesion of color coats becomes a non-issue.
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Offline Clint Ormosen

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Re: 1 more time........please
« Reply #7 on: September 23, 2009, 06:36:04 PM »
Clint,

Heck, I used fillers for years and have come full circle. I don't really use fillercoat anymore. Just un-thinned, non-taunting butyrate. 3 or 4 coats of that molasses and the grain is pretty much filled. It sands easily and you can get a very smooth base. And as you note, adhesion of color coats becomes a non-issue.

Yeah, I never noticed the grain really filling up any faster with stuff in the dope. Same as you I just use a few coats of either un-thinned or lightly-thinned clear dope. Except now I use nitrate dope for this part. I learned my lesson about fillers in the dope. It was bad.
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Offline Derek Barry

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Re: 1 more time........please
« Reply #8 on: September 24, 2009, 08:18:55 AM »
I use strait nitrate for two or three coats, just until I get a little shine. One or two coats 50/50 nitrate to stick the paper.One coat of filler on WOOD parts not open bays. I never touch the plane with a brush after that everything is sprayed on. Sanding between every coat makes life easy at the end of finishing.

Offline Bryan Higgins

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Re: 1 more time........please
« Reply #9 on: September 25, 2009, 12:16:07 PM »
Hello P51drb

Here is one artical that helped me:  Covering with Silkspan by Jim Ryan.

Bill Little also helped me.  Just ask him and he might help you out?

Bryan
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Offline Bill Little

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Re: 1 more time........please
« Reply #10 on: October 06, 2009, 01:21:29 AM »
Which ever dope method you choose, just remember to apply the top and bottom of the same wing panel at the same time.  If you cover only the bottom of say the outboard panel and let it dry, you will get a warp.  Oh, yeah, I always start each wing panel on the bottom, and work from the root towards the tip, stretching as I go.. ;D

I use Nitrate (I LOVE Randolph's Tinted Non Tautening Nitrate!) on the bare wood and to stick down the covering.  I feel it has a bit more solids in it than the butyrate dopes I have used.  Personal preference, but the nitrate has always seemed *stickier* to me.  I have never felt that the substrate was in too much danger of being exposed to fuel after all the other coats that go on it.

Shrink the covering with two or three coats of Sig Super Coat (or any other shrinking butyrate) then go to Sig Lite Coat.  It doesn't shrink as much as the CLEAR Super Coat.  I always use the same thinner in all my dope, so maybe that is why I don't have many problems with dope lifting when it is taped off, etc..  I basically thin all my coats 50/50 or so.

I wet the silkspan before I put it on like the others, a big towel is very handy.  If the silkspan starts to dry out to quickly, hit it with a spray bottle to dampen it, and be ready to start chewing dope off your fingers! LL~

I do the same when using silk.

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