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koverall ,stix-it and colored dope

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Old 01-30-2018, 10:21 AM
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wendell b gabbard
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Default koverall ,stix-it and colored dope

I am going to cover my guillows Fokker dr 1 with the koverall. I plan on giving the wood 2 coats of nitrate dope. My question is, when I use the stix-it to install the koverall, Can I use the colored dope over this later. How many coats of the SIG Fokker red will have to added for a good finish?

Last edited by wendell b gabbard; 01-30-2018 at 10:24 AM. Reason: wrong title
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Old 01-30-2018, 09:22 PM
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It depends. Is this a flying model or a static display model? For a model the size of the Fokker Koveral and multiple coats of dope is going to be pretty heavy. Koverall might even have enough shrink to crush the lightweight Guillows structure. If you really want to cover it with fabric I would suggest silk at most. The initial coat of nitrate seals the wood and to some degree acts as an adhesive. The Stix-it will adhere the covering just fine and is very compatible with dope. Nitrate dope makes a great primer and seals the weave of the fabric. Most colored dope is the butyrate type. You can put butyrate on butyrate and it goes on well over nitrate dope but you can't put much of anything over butyrate. If you are looking to fly the triplane then colored tissue or silk is a good way to get color without adding a lot of weight. I hate to be a stick in the mud and I won't say impossible but Koveral is probably both heavy and coarse for a Guillows model.

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Old 01-31-2018, 05:35 AM
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X2. Great advise.
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Old 01-31-2018, 07:57 AM
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wendell b gabbard
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Thanks for the advise. I am glad I ask first.Is 2 coats of nitrate enough before I appy the silk. For the color , would you go with the colored butrate dope or just use thinned latex paint.Thyanks in advance.
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Old 01-31-2018, 08:04 AM
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wendell b gabbard
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Just noticed you mentioned the dyed silk. That's probably what I will try'. How much ventilation should I consider when using the nitrate inside.?
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Old 01-31-2018, 08:50 PM
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Originally Posted by wendell b gabbard View Post
Just noticed you mentioned the dyed silk. That's probably what I will try'. How much ventilation should I consider when using the nitrate inside.?
How much intoxication/brain damage do you want? I'm only being a little bit of a smart aleck. Dope uses some really volatile solvents. Unless it is just a quick in and out of the shop patch job, I make a point of at least using an exhaust fan and I prefer to apply any dope out of doors or at least in an area with good ventilation. When you open that first can you will understand what I mean. On the upside the smell clears out pretty quickly.
On something like a Guillows model two coats of nitrate should be plenty. If you go to the Sig or Brodak websites there are probably guides on applying dope. The usual practice is to apply a couple of thinned coats of dope to the wood frame to seal the wood grain and to help with adhesion. This will raise some fuzz on the wood which can then be sanded off with fine grit sandpaper. If you use the tissue paper that came with the kit or silk you really don't even need stix-it. After you have primed the wood with nitrate dope then you can apply the tissue/silk. Thin the first coat by half with dope thinner. Cut each piece of covering to fit the area that you are going to cover. Apply the covering to the frame as smoothly as possible and then paint around the perimeter of the covering with the thinned dope so that it soaks through the covering to the frame below. This will soften the dope on the wood below and the covering will stick to the frame. Alternatively some people glue the edges of the covering with thinned Elmer's glue or even a glue stick. Shrinking silk or tissue is accomplished by wetting the covering with a fine mist of water. Don't soak the covering, just damp is enough. Lightweight structures, in the case of the Fokker this particularly applies to the rudder and stabilizer should be done one side at a time and pinned down while they dry to prevent warping. After the covering is adhered and shrunk than apply a coat of thinned dope to the entire surface and allow it to dry. Then a second coat may be applied. If you want to fill the grain of the covering a small amount of talcum powder can be added to the dope. Dope is essentially a lacquer. This means that if you are will to go to the effort you can apply enough coats, sanding between coats and then buffing the paint to produce a mirror shine. This is very attractive and will turn your Fokker into a nice paperweight. The Guillows Fokker is a nice exercise in building. I'm working on my second in between other projects. If you have any intention of flying it, lightness is your friend. Between covering various bits of the airplane with different colored panels of silk and or tissue you can replicate whatever color scheme you want for the airplane. You can even apply decoration such as stripes cut from tissue over the main covering using thinned dope just as you would if you were putting the tissue onto wood. For more information on covering small airplanes with doped finishes I would suggest having a look at the Flying Aces Club website.
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Old 02-01-2018, 05:44 AM
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Don't do it! Koverall will break that wood like a fat chick sitting on a candy bar. That stuff is STRONG. I've had Koverall warp wings on some of my planes it is so strong. Go with silk for the win.

Dope has a pretty strong smell. You could get pretty high if you don't ventilate the area. I always wear a good respirator with a charcoal filter when using it. That includes brushing. Keep doors open and run a fan. It's something you do in the garage, not a spare room in the house. If you do it in the house and you have a wife, you might not have one when the project is completed.

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Old 02-01-2018, 07:37 AM
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wendell b gabbard
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Thanks for all the info. I figured I would probably have to do this outside. What would be the lowest temperature ,60 deegrees? or warmer. Getting ready to dye my silk this weekend, and hope to have a few days of mild weather move in before long.I had no idea that the koverall would be that heavy or draw enough to warp the frame. I did a guillows se5a last year and used ultrakote for the covering . This was my first covering job. IT came out good, but I did have a issue with the wings warping. I used a jig and used more heat to take it back out. It was a major task. I have probably too much patience sometimes, but in the end ,everything was okay.Ended up at 8 oz. Not too bad with all the modifications, and additional wood I had to use to convert to electric. This dr I has been a bit more challenging., just wanted a more realistic covering. .
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Old 02-01-2018, 08:54 AM
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LOL, loving Carl's simile. Koverall has its place. It is very durable and between heat shrink and a couple of coats of dope it produces a very taut covering. I think there is still a picture in my gallery of the VK triplane I built back in the 90's and covered with coverall and Sig dope. How are you planning to dye your silk? It will probably pre-shrink the silk a little bit and you should probably pin it flat on a board so that it can dry smoothly. Alternatively, if you are going with electric power you have a lot more freedom in what you do for paint. Nitrate dope will act as a primer for almost any paint. I did a doped tissue finish on my 1/2A sized Mercury old timer but since I went with electric power I was able to use a light coat of model car lacquer for the trim color. In terms of a realistic covering, just do enough pigment to get the color you want. This is where the colored silk or tissue is really nice as it saves a significant amount of weight. Much respect for doing an RC version of the triplane. Micro servos and brushless motors really make it a feasible project. As to the question of temperature; dope doesn't care except to the degree that the solvents will evaporate more quickly in warmer weather. The temperature will likely have more impact on how quickly the silk dries when you shrink it. If you are comfortable, it is probably warm enough.

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Old 02-01-2018, 09:37 AM
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Wendel, Welcome to the "old school" world of covering with anything other then plastic film. There are many tricks, and techniques to covering with paper, or silk, and paint (dope). Another choice for covering is a paper called "silkspan", which has no relation to silk! It's available in three different weights; the lightest of which is heavier then tissue, and the heaviest is almost as strong as silk. A topic often overlooked is that paper, and cloth products have a "grain". What this means is that they shrink more in one direction then the other. For paper products the tear test will determine the grain. In one direction the paper will tear in almost a straight line, and the other direction it will tear in a jagged line. The straight line direction indicates the direction of greatest shrinkage. For cloth products, like silk, or Dacron, the shrinkage is greater with the warp, then with the weave. The reason this is important is that on wings and fuselages you want the shrinkage to be in the longest direction; span wise on wings, and length wise on fuselages. If the greatest shrinkage is chord wise the covering will droop between the ribs. On fuselages it will give the "starved animal" look with the covering sagging between the ribs. Another pitfall to watch out for is that dope has a tendency to blush in high humidity. If you live in a dry climate you shouldn't have a problem. If you have high humidity you might want to add blush retarder to your dope. Basically the retarder slows the drying process, so that moisture that has been trapped in the paint can rise to the surface, and evaporate. My last tip has to do with shrinking your covering. On very light structures, some modelers "per-shrink" the the covering to diminish the possibility of warping the structure. The next more aggressive process is to dry cover, and shrink with alcohol. A little more shrinkage will result with water. Wetting the covering before applying it will result in the greatest, or tightest covering job. This is difficult with tissue, because it tends to fall apart, but works great with Silkspan, and silk. My recommendation for your airplane would be tissue, or light weight silkspan. Apply it dry with thinned nitrate dope, and water shrink it. I use one of my wife's old perfume bottles to mist on the water. Good luck, Greg
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Old 02-01-2018, 04:39 PM
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wendell b gabbard
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I should have stated that I will be using 00 silkspan.I watched a dave platt video on covering and he explained the dyeing process for the silk. He used clothes pins and hung the silk up until dry, I guess it will shrink some. the name of the video is Back to Basics. I guess I got confused on the Koverall segment. He did say it would be a excellent choice for the ww1 planes.The video shows him actually covering a wing with silk and nitrate dope. Its kinda strange he did not mention the severity of the fumes or talk about any precautions using the stuff. Anxious. to get started , but think I will wait on decent weather , so I can work with it outside.
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Old 02-01-2018, 08:40 PM
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Wendell. Good choice on using 00 silkspan. The solvents in dope are similar to what kids indulged in, in "glue sniffing". In heavy concentrations you can get high due to oxygen deprivation. I've used dope for 60 years without a respirator with no problems, but would recommend good ventilation. Always keep in mind that many of us react differently to different chemicals. So what doesn't bother me, might make breathing difficult for you, or someone else in your household. Just use normal precautions that you would use with any paint products used in your home, or garage.
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Old 02-02-2018, 09:30 AM
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Ditto the good choice on the silkspan. If you have been watching the Dave Platt video you are probably in pretty good shape. If you do a youtube search for Windy Urtnowski and or Brodak dope there are some good videos on dope technique. It is mostly U-Control stuff but the technique applies. RFCafe also had tutorial videos on Silkspan and dope.

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Old 02-02-2018, 10:29 AM
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In the past I've had the honor of doing the controline stunt concourse judging st the AMA Nats. This provided the opportunity to examine the best airplanes, very closely, including Windy Urtnowski's. His airplanes have always been among the best, and several times he has been awarded a perfect score. Similarly, Dave Platt is not just a great scale, and all around modeler, he is the standard to which others have been compared to for almost 50 years. So the take away here is that any techniques recommended by either of these gentleman should be followed whenever possible.
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Old 02-03-2018, 07:31 AM
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Thank you all for the reply's. It is probably going to be a couple weeks before I start covering. I mounted my servo"s a little too high in the cockpit area and going to have to redo in order to get the pilot where it should be.Decided to move my receiver back a little bit too. Thinking if I have to get to them in the future , I can do so through the cockpit I .Hate having to redo things , just a whole lot of things involved in setting it up for electric.I plan on covering the model in my outside building,14x20 which has vents in the ceiling, and a window fan that can be reversed to draw out fumes also.I am around a lot of paints, stains and sealers at work where I do maintenance, The oil based stain is not my favorite thing to do inside. I stained some doors once ,and had them placed flat down on my work table. Where the vapors were coming straight up at me ,it was extremely strong.I set up a couple fans and retreated to the outside every 10 t0 15 min.I was just curious how strong the nitrate dope really is. I know sometimes, people can over exaggerate on things.I noticed on the back of the nitrate can , that it states to use sig supercoat for filling the last coats, due to the regular clear nitrate shrinking enough. I thought I would be using the clear nitrate for this also. I don't recall this mentioned in the video, Is this necessary,
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Old 02-03-2018, 08:29 AM
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Since you are going electric the Supercoat isn't really necessary. Nitrate isn't proof against glow fuel and the Butyrate dope is at least fuel resistant. Even it needs raw fuel wiped off right away. I would suggest that for your project that you not worry about a glossy finish. WWI aircraft weren't particularly glossy to start with and the finish soon dulled out in the field. Mechanics would wipe them down to mop up the castor oil but they never got a wash and wax, so to speak. In our case the dope serves to adhere the covering, shrink it and to seal the grain of the silkspan. I don't know how much difference it makes on silkspan but on a fabric covered aircraft airflow through the weave of the cloth makes a significant difference. As to the strength of the fumes, everyone's perception is different but dope does use a significantly more volatile solvent. Relatively speaking it's like the difference between gasoline and diesel. One smells stronger but the other has way more vapor. On the up side you won't use nearly the quantity of dope to finish a triplane as you used stain and varnish to do a wooden door. It is certainly not as nasty as some of the catalyzed paints like Imron. Once you open the can you will get a feel for the strength of the fumes. Given that you have a good workspace and you have some experience with paints and solvents from work, I wouldn't fret over it too much. If you find the fumes to be troublesome get yourself a filtered paint mask.
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Old 02-03-2018, 09:00 AM
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Great, I am thinking about the sig flat coat for the final coat, so I can end up with the dull finish.
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Old 02-03-2018, 10:55 AM
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Wendel, Here's another tidbit of information. All of the "dopes" create shrinkage. Besides regular nitrate there is a non-taunting nitrate, which shrinks some, but less then plain nitrate. A lot of us like the non-taunting for use on light weight structures that might warp with regular nitrate. There are modeling sources for non-taunting nitrate, but I've gotten mine from full scale aircraft sources like Wicks, or Aircraft Spruce.
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Old 02-03-2018, 11:09 AM
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Great,alot of good info on here.Really appreciate the replys.The only thing I don't like about learning is when you look back and think, Boy I ask some dumb questions.
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