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  • November 25, 2020, 04:22:20 AM

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Author Topic: current thoughts on basic covering and finishing???  (Read 764 times)

Offline Charles Hofacker

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current thoughts on basic covering and finishing???
« on: June 21, 2020, 01:31:25 PM »
I'm framing up my next PA contest model. I plan to use it in the beginner PA (my first entry in PA). I know that finish is not judged but just the same I want to do something that looks nice. So far my construction has been 50 foot finishes - it looks good at 50 feet. I'd like to get to at least a 10 foot finish y1. What are the current thoughts on covering and finishing materials? There are numerous comments in this board about kinds of finishes epoxy, urethane, Krylon, etc., etc. but not much on base materials  Silkspan and dope is the old traditional stand by but requires many light coats of filer and very very careful sanding. Lots of very very careful sanding... then there is Monocoat et.al. but it still looks like a Monocoat covering. No matter how hard I try I get many tiny wrinkles over small radius compound surfaces and edges like elevator edges and wing tips. Trim without bubbles is a big problem. Polyspan is another option but it doesn't mold easily, if at all, over tight radius compound curves and wrinkles and over laps don't sand easily. It just frizzes up. So far I have been covering wings with Monocoat and spraying solid surfaces with rattle can colors over minimal filling and sanding. What do you suggest for moving p to the next level of finish. I'm not looking for a concours d'elegance finish just a reasonable finish for my level. Hopefully light weight and can be accomplished by an average builder. Thanks for your comments!


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Offline Dan McEntee

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Re: current thoughts on basic covering and finishing???
« Reply #1 on: June 21, 2020, 04:45:07 PM »
   The first thing to remember in finishing a model airplane is that there is NO such thing as a free lunch! Just about every system there is requires some work and techniques to learn. You only get better with practice and refining your techniques as you learn. Take a Monokote finish for example. In my experience, a good Monokote finish can look really nice, the ten foot type that you refer to, but it still takes work. It may not be as smelly as a dope or painted model but is probably just as much work to get it to look good. Monokote won't hide a poorly constructed model or a poorly sanded model. Sparky has a saying the the finish of a model begins with the first piece of wood cut and there is a lot of truth to that. If you pay attentions to details as you build it, and make an air frame that is as straight as you can make it and free of poor fitting parts with lots of bumps and gaps, the finishing actually gets a bit easier.  Allen Brickhaus has a system of using iron on coverings for wings and tail surfaces and a thinned finish cure epoxy coating that was brushed on to solid wood surfaces, then sanded smooth and pained with rattle can paint like solid colors of Rustoleum and True Value Hardware X-Orust. He described it in detail in a few of his constructionist articles. It's not a complex system but does require some elbow grease and sanding and is not expensive. If you are still in the crashing stages of learning the pattern  you want to keep finished simple and inexpensive. You just have to pick one system that you think fits your situation and stick with it and develop the skills and techniques for it. It's like the old saying, the only way to get to Carnegie Hall is Practice, practice, practice! As you get better at the this type of system, you can use that experience and maybe try the dope and auto paint finishes as time goes on. What ever you pick, you won't master it on one or two airplanes, but keep at it and learn from your mistakes. And everything that you have mentioned in your post, has been covered in great detail several times through the years on this forum. Learning the good search finction skills can be real handy at 3AM when you want to know a detail about something!
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Offline Charles Hofacker

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Re: current thoughts on basic covering and finishing???
« Reply #2 on: June 21, 2020, 06:54:32 PM »
Good advice as I expected - thanks! My latest build is  a Yates Mad Man that I plan to enter in OTS. it weighs 34oz and is powered by an OS Max 25FP. plane is straight and the joinery work is better than average IMHO. I really took my time and did my careful best. also it was a very good laser cut kit. but the finish is so so. The wood grain shows  and the base color is thin in spots and some areas are not as glossy as others. I have much to learn about covering and finishing.

Offline T.J. Vieira

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Re: current thoughts on basic covering and finishing???
« Reply #3 on: June 22, 2020, 05:44:50 AM »
tissue and dope all the way....  get your wood flat first (seams, grain, etc), and the tissue goes pretty quick.  i don't really mess around with the fill coats.  three to five good coats, sand with 320, another 3 to 5, sand with 320 until you're convinced it feels and looks like a million bucks.

Duplicolor primer works pretty good, sands ok with 400 and 600.  Plus, it'll make all of your mistakes stand out crystal clear, which is exactly what it's supposed to do!  sand until it's transparent, touch up any needed spots, sand again, then decide when you're ready to spray dope!  The top looks pretty if everything underneath is pretty....

Offline Steve Berry

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Re: current thoughts on basic covering and finishing???
« Reply #4 on: June 23, 2020, 10:12:21 AM »
For a master class on finishing, one of the best is Windy U's series on his Tribute plane. I've watched it all the way through and left amazed at how simple it can really be. Simple as in you don't need a lot of fancy equipment. A wide, high-quality brush or 2 (or 3), lots of wet-dry sandpaper in a variety of grits, a simple HVLP spray rig with compressor, optional: airbrush, and lots of patience.

If I remember it correctly, he brushed 3 coats of dope, thinned 50/50. Doped on the silkspan on the entire surface (no built-up tail and a solid-surface composite wing), rubbing the dope in to get it to adhere to the undercoats. 3 more coats of thinned dope, sanding in between each coat (it should powder off). When he was satisfied with that, thinned coats of Brodak silver, sanding in between each coat and going over all the little imperfections. At that point it was a simple thing to mask or backmask as needed and spray the color. When that was finished, he sprayed the clear. When that cure/dried, time to final sand and then buff. Lots of steps, lots of patience, and lots of sanding & fussing, but not outside the realm of mere mortals.  Oh, yeah, the entire finish was Brodak dope that he had decanted. From base coats to top clear coat, all Brodak.

Steve

Offline Randy Powell

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Re: current thoughts on basic covering and finishing???
« Reply #5 on: June 23, 2020, 11:01:29 AM »
I've always been a silkspan guy, but I'm considering going to polyspan.
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Offline Ken Culbertson

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Re: current thoughts on basic covering and finishing???
« Reply #6 on: June 23, 2020, 02:17:07 PM »
I've always been a silkspan guy, but I'm considering going to polyspan.
Once you figure it out and stop swearing it will grow on you.  Once I learned how to use the heat gun to make it behave I won't use anything else on open areas going forward.

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Offline Shorts,David

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Re: current thoughts on basic covering and finishing???
« Reply #7 on: June 23, 2020, 03:15:15 PM »
I will speak as an expert at being a beginner in finishes. Huh? What I mean is, I'm right there with you, except my newest plane has finally achieved a ten foot finish. I will say that I have seen "perfect" finishes with every product under the sun, so I believe there is a level of commitment to a method. On my first polyspan job I was willing for it to look like sin just so that my second job would look much less sinful, and it does.  Darn, I'll say that everyone who says just take your time and you'll get a good finish. Bull, it also takes practice and practice and maybe more practice.

But, I like to factor in time and cost and for my latest plane I went back to ultracote. If you aren't doing it yet, remember you can use the heatgun prior to using the iron on wingtips and odd corners. Also, ultracote has that new parklite covering in limited colors. It shows a bit of grain through it, but it is easy to use and very lightweight. If I can get monocote to go on like those few experts with the product, for time invested and cost, it is unbeatable. But, since I haven't yet, I'll probably keep playing with the polyspan too.

Offline Peter Nevai

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Re: current thoughts on basic covering and finishing???
« Reply #8 on: June 24, 2020, 04:27:25 PM »
Well it is true that monokote will always look like monokote, because, well, its monokote. That however does not mean you need to put up with air bubbles or wrinkles. The first thing is the wood needs to be smooth, and dust free. Otherwise imperfections will show through and monokote will not stick to balsa or filler dust.

Number two, when doing a super monokote finish you need plenty of material. Any surface you cover needs at least 2 inches or more excess. You need enough overlap at the edges or ends to be able to get a good grip on without burning your fingers with a heat gun or iron. To get wrinkle free small curves and edges you apply heat as you pull and stretch the covering around the curve or edge. And I mean heat, pull around and stretch the covering all the way around. once you have one side done trim it with a #11 exacto or single blade razor and repeat for the other side.

This means you will have to be able to support the object so it does not break or warp while performing the action. I say this because it does take a fair amount of pull to get the proper stretch in the material. Once both sides are done you seal up the seam with the iron. And guess what? No more little wrinkles around curves. To do super monokote properly entails lots of waste, and as part of your weapons of destruction you will need a heat resistant glove, a damp rag or towel, an covering iron with cloth boot and an inexhaustible supply of new sharp razor blades. Any larger trim is not done with the sticky monokote trim. You use regular super monokote some water in a spray bottle.

The models below were both done using super monokote exclusively

If you find the material bunching up too much along a curve monokote is somewhat forgiving just reheat and pull it up then work the material to smooth out the excess, you can do this maybe once or twice along any edge. Remember that you gave yourself plenty of extra material to grab onto. After a bit you will get a feel for just how much to stretch and how to approach a curve or corner where you will rarely have to reheat and reposition the material.

You cut your trim wet the side of the trim with water slide into place and squeegee and blot the water out then let dry. You will end up with no air between the material and then you just seal it down either with the heat gun while wiping it gently with a damp rag or you can use the iron. It takes practice and I would suggest you practice the techniques on some scrap balsa pieces first to get a feel of what it takes to get the results you want. Squared corners require some planning on how to cut and overlap the material but that would also be the same with tissue or any other covering.
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Offline John Leidle

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Re: current thoughts on basic covering and finishing???
« Reply #9 on: June 24, 2020, 11:09:49 PM »
I've always been a silkspan guy, but I'm considering going to polyspan.
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Offline Randy Powell

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Re: current thoughts on basic covering and finishing???
« Reply #10 on: June 25, 2020, 09:02:56 AM »
Hi John,

I've always like silkspan because it's easy to work and very forgiving. Problem is, it's gotten very hard to acquire. I tried the exam table paper but it's not really silkspan. I'm told Sig still sells SGM but when I tried to order, they said it was out of stock. So, being the dinosaur I am, I'm reluctant to try something new. Seems I may not have a choice. I have enough silkspan for 2-3 more planes then I'm going to have to change, it seems. Oh well, if I go to polyspan, I can also move entirely to auto finish products. No more dope.
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Offline Jim Hoffman

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Re: current thoughts on basic covering and finishing???
« Reply #11 on: June 25, 2020, 01:41:58 PM »
Charles - You stated in your original post that you are flying at the beginner competition level.  If that is the level of your flying today, I recommend Monokote because it is easier and faster to repair than any painted finish.   BTW a GOOD Monokote finish takes lots of care.

When you can put lots of flights on a model with any mishaps, consider a dope finish. 

My favorite covering is Polyspan because of its durability.  I like dope substrates and colors because they are also easy to work in and fix.  I use automotive urethane top clear coats because they make the airplane extremely tough and resistant to fuel and other contaminants

ALL the techniques can work and require effort, skill, practice and patience. 

Offline Charles Hofacker

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Re: current thoughts on basic covering and finishing???
« Reply #12 on: June 27, 2020, 11:19:10 AM »
Good comments from y'all. Thanks. As several people said it takes practice I'm sure. What I hope to achieve is a better job each time I do it. I think my next step is to get a good finish on solid parts and cover the open parts with monokote. Once I can get a good finish on solid surfaces I'll work on what to do with open structures. There does appear to be some risk using hardware store rattle can filler and paint - dope is good but it must be ordered and shipping is expensive. One person has a success and some one else has a disaster with the same stuff and, of course, the really good stuff is poisonous or has some other nasty characteristic requiring special handling. Life is a challenge  y1. And incidentally Brodak silkspan is $$$$$$. 6 bucks for two sheets 24x36 and 14 bucks for shipping! ~^ like wow.

Offline Brett Buck

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Re: current thoughts on basic covering and finishing???
« Reply #13 on: June 27, 2020, 12:53:21 PM »
There does appear to be some risk using hardware store rattle can filler and paint - dope is good but it must be ordered and shipping is expensive.

    Dope is particularly fragile (chemically and physically) and hardware store paint is a crap-shoot. All the top appearance winners are using automotive basecoat colors and urethane clear, easy-to-use and bulletproof. I am using epoxy colors and urethane clear.

   But Jim is absolutely right, to start with, this takes too long and is too hard to repair for your stated purpose. You can do an absolutely excellent and competitive job with iron-on covering on the wing and tail, and paint on the fuselage. I qualified at the NATs 6-7 times with Monokote wing/tail and epoxy paint on the fuselage.

    If you absolutely must use paint everywhere, at least give yourself a chance and use polyspan, it's far more durable than silkspan, and I know for certain that at least two 20 point airplanes and many front-row finishers have used it, it is the replacement for silkspan (which is NOT what you get from Brodak, as far as I can tell).

     Brett

Offline Joe Ed Pederson

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Re: current thoughts on basic covering and finishing???
« Reply #14 on: June 27, 2020, 01:22:21 PM »
   
    If you absolutely must use paint everywhere, at least give yourself a chance and use polyspan, it's far more durable than silkspan, and I know for certain that at least two 20 point airplanes and many front-row finishers have used it, it is the replacement for silkspan (which is NOT what you get from Brodak, as far as I can tell).

     Brett

Like Brett says, I've bought "silkspan" from both Brodak and Sig in the last couple of years.   They aren't "real" silkspan.  Neither have any wet strength.  You must be very careful to get the smoother side up on either Brodak or Sig or you will get a very coarse feeling surface even after 5 coats of dope.  And of course, I know that from personal experience.

Polyspan must be put on with the smoother side up, but its easier to tell which side is smoother.  I learned this from others (Sparky, etc.): don't even think about touching polyspan with sandpaper until you've got at least three coats of clear on it.  Sparky and others have videos on youtube on applying/finishing with polyspan.

Joe Ed Pederson

Offline Ken Culbertson

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Re: current thoughts on basic covering and finishing???
« Reply #15 on: June 27, 2020, 11:05:23 PM »
Let me pass on something I stumbled across when trying to patch a polyspan wing.  Maybe it is not new but it was to me.

The "weave" in polyspan is not very uniform and there are places where it will quickly form pin holes if you heat it too much.  I did this and it took several extra coats of dope to seal.  Then for some reason, probably because I was in a hurry, I used my heat gun to dry the dope (in this case Randolph's Nitrate).  I noticed something quite by accident.  The dope caused the polyspan to sag and the heat tightened it but it also dried the dope enough that it locked it in place tight and those little ridges that form on sides of the capstrips when the dope dries were gone. It was as tight as a drum, there were no pin holes and the capstrips barely showed with no rounding at the edges.   Same procedure for the second coat.  Third coat didn't sag so I did not need the heat.  Getting the dope to dry before it could allow the pin holes to form probably saved me 2 coats of clear.  I was able to lightly sand without worrying about sanding through at the edges of the capstrips for the first time.  I have used this for original work on two ships since with excellent results.

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Offline bob branch

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Re: current thoughts on basic covering and finishing???
« Reply #16 on: November 21, 2020, 09:03:42 PM »
If you want a pimer on film finishing and to see how it can be done I did a build thread of the Brodak T-Rex  https://stunthanger.com/smf/gettin-all-amp'ed-up!/t-rex-electric-build-thread/    that contains a section on how to do it corrctly. You will be able to see how the heat gun is used and how compound curves are accomplished. I still have the plane today and it still looks very nice.

bob branch

Offline Don Jenkins

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Re: current thoughts on basic covering and finishing???
« Reply #17 on: November 22, 2020, 06:49:37 AM »
No matter what finish you choose, the framing, carving/shaping and basic wood working along with CAREFUL sanding is the key to a good finish.  Putting a fancy/shiny coat of paint over a POS, looks like a POS, even from 50 feet!  Just my opinion.

Don

Offline Avaiojet

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Re: current thoughts on basic covering and finishing???
« Reply #18 on: November 22, 2020, 02:11:59 PM »
I think the perfect system is mine! I can name drop myself. ;D

And I didn't put my system together overnight, it took plenty of experimenting/test of many products. This is why I settled on silk and now only silk.

BTW. I do my own parroting and I don't parrot others because I've never tried anyone's system.

A system? Remember, it's 2020 and color dope is no longer needed.

You can paint your model in weeks or days. I can do colors over colors the same day.

No expensive spray equipment, cans to open or mix, no cleaning of spray equipment either.

Sure, you need to learn the medium. The medium,  LL~ AEROSOL CANS, but the ones which are not commonly recommended. Gee? The brand that hardly ever gets mentioned at all actually is the one I found to be the best. #^

KRYLON!! And what a selection of colors!

I've mentioned my system many times and I have many Builds explaining exactly what I do.

Here's proof of the pudding. I actually have painted models done with my system.

Charles, if you have interest, just send me a PM.

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Offline Brett Buck

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Re: current thoughts on basic covering and finishing???
« Reply #19 on: November 22, 2020, 02:41:59 PM »
What are the current thoughts on covering and finishing materials? There are numerous comments in this board about kinds of finishes epoxy, urethane, Krylon, etc., etc. but not much on base materials  Silkspan and dope is the old traditional stand by but requires many light coats of filer and very very careful sanding. Lots of very very careful sanding...

    I would suggest, if you are going to paint it, polyspan over the open bays, and silkspan or carbon fiber mat over the solid surfaces. Lite-coat dope (NOT Brodak or Super-coat) to create the substrate, and then switch to epoxy primers and colors. It's durable, reasonably fast, and looks pretty good even without the clear. Plus, it is completely fuelproof. Straight dope should be a non-starter, it is not nearly as durable and takes endless work and a fair bit of skill to achieve good results.

   But, if I was in your spot, I would strongly recommend iron-on covering for at least the wing/tail, and silkspancarbon fiber mat with lite-coat on the solid surfaces, and epoxy.  Just like anything there is some technique to applying iron-on, but so is painting it completely. With care, you can make it nearly indistinguishable from a good painted finish - Bill Fizgerald had people asking him what kind of dope he used, *at the NATs*, when it was plain old white monokote. Last time I saw the airplane it still looked like a very good doped finish- and the rest of the (painted) parts looked like they were 40 years old yellowed epoxy.

   If you do that, and, forgive me for mentioning it -  given the likely lifespan of the next few airplanes - you want something that is pretty fast and easily repaired. Iron-on covering is *extremely unforgiving* of bad technique, but it is undeniable fast. Similarly, with epoxy, you can omit the silkspan and dope, just put some grain filler like Timbermate right on the wood, sand it flat, then just apply color epoxy right over it, sand it, put on one more coat, and you are good to go. The grain will show, eventually, to some degree, but that takes the finishing process from 3 weeks in a push, to 3-4 days.

    Brett

Offline Avaiojet

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Re: current thoughts on basic covering and finishing???
« Reply #20 on: November 22, 2020, 03:49:34 PM »
If I had interest in using spray equipment, I would use Epoxy paint.

There are many reasons for using Epoxy paints on models but I'll only mention a few as Brett already has.

Color coats stick well to each other with a bit of scratching, but after all is said and done, when the final trim color is put in place, you're finished!! No clear coat is required for fuel proofing. That alone is an excellent reason to us Epoxy.

I still have a model hanging around from my R/C days which I painted with K&B Epoxy paint a long time ago. Looks like it was painted yesterday.

CB
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