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Author Topic: Prepping silkspan problem  (Read 1720 times)

Offline J Motta

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Prepping silkspan problem
« on: August 19, 2022, 08:43:52 AM »
Can anyone help? Iíve covered my first wing with silkspan and have primed it. Three coats of dope on the wood and three coats after. Iím using Rustoleum 2x sanding sealer which seems to work very well. My problems are that Iím getting some fuzzies while sanding and if I come across a small raised blemish do I either sand it out and dope a small piece of silkspan over it or just dope it. Do I also just dope and prime the fuzzy sections? Am I sanding too much maybe?
                                                                                                            Frustrated Joe

Online Craig Beswick

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Re: Prepping silkspan problem
« Reply #1 on: August 19, 2022, 09:22:52 AM »
It sounds like you have accidentally put the dull side up.
Just keep doping and patch as necessary. Remember to tear the patch not cut it. The tear will be invisible.

Craig
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Offline Ken Culbertson

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Re: Prepping silkspan problem
« Reply #2 on: August 20, 2022, 10:54:46 AM »
I have done that accidently.  I saved a lot of coats by "sanding" after a coat of dope with the backside of the sandpaper then applying another coat after.  Burries those fuzzies VD~
I have also found that shrinking polyspan after a fresh coat of dope early on saves a couple of coats since it seals the pores faster.

Ken
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Offline Tim Wescott

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Re: Prepping silkspan problem
« Reply #3 on: August 20, 2022, 12:20:21 PM »
You say silk span, but did you mean poly span?  Silk span has a shiney side, but no fuzzies as such and it does not  matter if the dull side is up or down. Poly span on the other had is very particular, the shiney side MUST go on top.

If you sand into the silkspan then it does get a little fuzzy -- but it gets taken care of with more coats of dope.  I haven't sanded into polyspan yet -- because I haven't used it yet.  I'm sure I'll learn just how delightful that experience is on the next plane, which will be getting polyspan.
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Offline Ken Culbertson

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Re: Prepping silkspan problem
« Reply #4 on: August 20, 2022, 01:42:54 PM »
I haven't sanded into polyspan yet -- because I haven't used it yet.
Quote

By all means cover one wing with it upside down.  It is a right of passage.  Like your first beer. LL~

Ken
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Offline J Motta

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Re: Prepping silkspan problem
« Reply #5 on: August 22, 2022, 08:49:09 AM »
It was definitely silkspan but since it was covered a couple of years ago and my first build I canít remember if I knew about the sides. Either way with more primer or dope looks like Iíll be giving up some weight for appearance and the next plane will be sweeeet lol

Offline Gerald Arana

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Re: Prepping silkspan problem
« Reply #6 on: August 22, 2022, 10:05:46 AM »
This is just what I do for the fuzzies; I use a razor blade held perpendicular to the wing (fuse, etc.) and carefully (read lightly) scrape the fuzzies off.

And yes, I put some polyspan on upside down. Fuzzed up just fine. Got out the ol razzer blade and "voila" no problem.

Good luck, Jerry

Offline J Motta

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Re: Prepping silkspan problem
« Reply #7 on: August 26, 2022, 07:52:11 AM »
Huge help everyone. Thank you
Joe

Offline Motorman

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Re: Prepping silkspan problem
« Reply #8 on: August 26, 2022, 10:45:08 PM »
Not sure but I thought you had to put on enough dope so you don't touch the covering when leveling with the sandpaper?

Offline MikeyPratt

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Re: Prepping silkspan problem
« Reply #9 on: August 28, 2022, 12:24:24 PM »
Well it takes a minimum of of four coats of dope after the model is covered, then a carful light sanding then another coat of clear to act like a seal and/or blocking coat, it should start to shine from just the clear before going any further.  You can give two coats every day, one early in the am, the other lat at night.  Depending on what Iím doing, I like to apply enough dope on the model to make sure Iím only sanding the clean dope.  I havenít tried using a thing thatís not dope period!  Primer is either sanding sealer or clear withe zinc striate added to the clear, about one heaping table spoon for a quart is all you need.  Brush two coats of the primer and let it dry for a few days, then wet sand with 600 sandpaper, when you satisfied shoot another coat of clear over the model again to seal off the base.

From this point on spray all colors making sure to seal the edges of your tape with clear dope.  Once you trim is applied and the tape is remover genteelly rub the the edges of your trim colors with a credit card to remove the high point of the edge.  Let the paint cure for a few days and lightly sand the tape edges with 600 wet or dry sandpaper (wet).  Wash off the model with Windex and paper towels (twice).  Mix up the the clear dope by mixing up two quarts of clear mixed with thinner 50 50%, now spray another coat of clear on the tape lines on the entire model.  Once that is almost dry, give the model another coat of clear.  Let that dry overnight and carefully check to make sure there are no imperfections in the paint.   Again, lightly sand the tape edges with 600 (wet) or dry and clean the model with Windex and paper towels.

Using a tack rag between evert coat gently remove any dust particles and spray a new coat of clear dope.  You will notice the the edges of the tape lines are all but gone now.  Shoot the rest of one quart of clear and allow that to dry.  Again, if your satisfied, start shooting the second quart of 50 50 dope until the the clear is gone.  Then allow the dope to dry for a week or more and the dope to shrink down, (at this point you can test fly the model) and touch up any chips that have shown up.

Again, clean the model with windex and paper towels, starting on the bottom, lightly sand the clear dope with 1000 grit wet or dry sandpaper (wet) until you have a dull Matt finish over the entire model.  Now start your rubbing out process using 3M fine rubbing compound, then switch to a very fine rubbing compound.  Apply a good wax and buff up the shine with the wax, now it should be very shinny and looking great.

Note:  At this point you can replace the second quart of dope with PPG high quality automotive clear.  Go easy itís weight is way more than dope.  Apply two coats of the clear, the first coat a light tack coat, and the second coat an even smooth coat and allow to cure for a few days before buffing out.

Later,
Mikey Pratt

Offline J Motta

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Re: Prepping silkspan problem
« Reply #10 on: August 29, 2022, 08:43:41 AM »
Might not be enough dope. Is it ok to dope over primer and what ratio of dope/thinner should I use?

Offline MikeyPratt

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Re: Prepping silkspan problem
« Reply #11 on: October 11, 2022, 12:54:23 AM »
Hi Joe,
I hope you have worked this problem out on this model?  In my opinion, I think your problem started with the primer, if You are going for a dope finish, donít put anything on thatís doesn't say dope, period.  You have already made a big commitment by building & covering the model, why take a chance on it by spraying some a non-dope primer on it, if this was a sport plane, them maybe, but not me, itís just not worth it to chance it. 

Iíve painted a lot of different types of models over the 50 years, from dope, to epoxy, enamels, car paint or what have you, donít mix different types of paint.  Use them on your lawn chairs, if they look crappy, who cares!

Mikey Pratt

Online Dave_Trible

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Re: Prepping silkspan problem
« Reply #12 on: October 15, 2022, 01:49:17 PM »
Just a point from reading here.  Real silkspan doesnít have a smooth side.  Itís the same both sides.  Japanese or other tissues DO have a slick side.  There will always be some Ďstubbleí that sticks up after the first coat just like balsa.  You can very lightly knock it down after the second or third coat and then keep going.  The number of clear coats will depend on the brand of dope and how much it is thinned.  Certified is about the most dense.  Cut 50% about three coats will fill the paper.  Others may take 5-6 coats.  Iím not a user of filler or primers.  These are heavy.  An extra couple coats of dope and wet sanding will have good results.

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Online 944_Jim

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Re: Prepping silkspan problem
« Reply #13 on: October 15, 2022, 04:35:27 PM »
Mr.Joe,
It's been several weeks since you shared your problem. How is this going for you?

Thanks in advance

Offline J Motta

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Re: Prepping silkspan problem
« Reply #14 on: November 09, 2022, 07:01:57 PM »
Thank you for asking. Iíve been sidelined on getting another plane ready for a contest. Hoping to continue soon.


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