Painting Model Airplanes with Urethane Paints
I would like to preface this with a simple statement. This method is not set in stone and there are many different ways to paint with Urethane paints and get the same results. These are the steps that I have found over the years that help make it easy and quick to get a good looking high gloss finish in just a few short hours.
The product I use is DuPont ChromaBase paint and DuPont ChromaClear.
Finishing with urethanes can be very easy quick and rewarding. I used SIG Nitrate dope as my under coat. Used this to prep the wood for covering and sealing the surface. I like SIG nitrate dope it is light and easy to work with. I always use SIG thinner when using SIG dope.
From bare wood I apply 4 coats of clear dope thinned 50:50. I sand between the third and fourth coat. Also I sand after the fourth coat. At this point I apply the covering I am going to use. I use PolySpan on open bays and carbon fiber mat on the sheeted wood areas.
After the four coats of dope the PolySpan was then applied with 90% thinner 10% dope mixture. The thinner penetrates well and activates the dope underneath and it sticks great.
After the covering is applied I brush down 2 coats of dope, thinned 50:50, over the entire airframe. Then sand out smooth. It works very well. I brush down three coats of 50:50 dope over the Poly Span it takes more dope to seal it. Then sand smooth. Do not cut into the PolySpan. Just cut the dope off of the top and move to another area. It will not feel as smooth at this point as say silkspan would. It will fill very easy so don't worry.
Next comes the filler. I use Zinc Styrate(sp) and nitrate dope. This is extremely light and can be spayed on and sanded off many times with very minimal weight gain. I used two coats on my last plane and it was ready for a guide coat of filler. I used the English Color house auto primer with their standard lacquer thinner. This is a great product and pretty much the same wherever you go. The primer dries extremely fast and can be wet sanded in just a few hours after application. This primer is very heavy so please be very careful when using it. I mix it 1 oz of primer to 5 oz of lacquer thinner. This is a very hot solution so have your canopy and other plastic parts that are attached to the plane covered very well. I double up on the tape on my canopy to keep it (thinner) from taking of the dye. I spray this stuff on very lightly and use it as a guide coat only. It will show where I have not fully filled in the areas. It will build up in layers so you can do your final filling with this mixture. With this much thinner in there it dries in about 10 minutes and can be sanded out in about 20 minutes. I like to sand and apply again to the area in question and see if it flat enough. With the fast drying solution you can do it all in one evening.
Once your surface is up to your satisfaction the fun starts. You should probably think of a paint scheme ahead of time. This helps when applying tape and trim and letters. So you should head down to your local sign shop and have some stencils cut out of the name and numbers you want use. All the letters numbers and such have to be painted for the best results. Be careful the sign shops vinyl is very sticky and can rip covering when pulling it off. You can also cut your own stencils out of friskit paper or Gerber mask. I prefer the Gerber because it is very low tack and pulls off with no complications. I also use a hair dryer and lightly heat it when pulling the mask and tape of any kind off the plane. This will help release the adhesive. I buy Gerber Mask by the yard and take it to the stencil shop and they cut it how I like it for a very small cost. You can also cut your own out of it with the trusty old no. 11. Reese Supply here in Irving Texas carries it. You can look them up and they will sell you what you want. They are a supplier for sign shops. I am sure there is a supplier in your area.
Now clean off your table and get ready for a day of painting. The colors I used on my latest Bear were 2000 NASCAR red, black, and 1997 Corvette Blue. The really nice thing about these paints is you can get a chip of a color and they can match it. Or you can pick from their book of literally thousands of colors.
Prior to painting wash your hands. Now wipe the plane with a tack cloth. This will remove any dust that is still laying around on the surface. I have never used prepsol or material like that. Wiping the plane with liquids like that scares me and I advise against it. Between each coat I wipe with tack cloth.
The paint is sprayed between 30 and 40 psi. I have found lately that I can spay with as little as 20 psi. I would recommend using the prescribed amount of pressure. Also a touch up gun is the gun of choice. Mine was about 40$ at Home Depot. The clear is sprayed a 40 psi do not deviate from this setting.
You should also purchase a good painting mask they are about 30$. You should never spary chemicals of any sort without one. If you do not use a mask you will end up with an upset stomach, light headed, sick, and some harsh chemicals in your lungs that don't go away. Do not take this lightly no model is worth your health. With a good mask and a well ventilated working area all this is not a factor. You should also cover yourself. Wear a cap or baseball hat, rubber gloves the thin dr. gloves work best, long sleeve shirt and pants. Protective eyewear is always recommended.
You need to know that this paint (the paint that will be seen) cannot be color sanded before clear. The sanding strokes will show and you will not be happy with the end result.
After you are fully satisfied with your final coat of primer it is time to paint the main color of your paint scheme. Now if you are planing on one color and just some highlight lines or numbers and letters only, go ahead and paint the entire aircraft the color you have chosen. In my case I was going to paint the entire tail section and the nose red. I taped off the tail and the back half of the fuse and the nose so I would not be painting over an area that does not need the color. This is back masking. (this is how the pros keep it really light) This also saves paint. The colors I choose are not cheap. The coverage is so good that I will have these colors for along time. The shelf life is in the average of 4 years. I have used paint as old as 6 years and had no problems. Now I have the entire aircraft except for the tail section and the nose 1997 Corvette blue.
Now after about 30 minutes I tape off the front half of the fuse and the nose paint the entire tail section and the nose 2000 NASCAR red. I wait 10 minutes and remove the tape. At this point I am smiling because I can see it all coming together. I have been working about 4 hours since I started painting.
Since I already have red mixed up I lay down all of my stencils that will be painted red. In this case it was all the letters and numbers on the wing were going to be red. I put down the stencils taped all around all the edges to keep over spray off. Spray the color. Wait 15 minutes. Check and see that the red is covering the blue all the way. This may take two or more coats. This is the case with any light color going over a dark color. It doesn't matter what you are painting with this will be the case. After I am satisfied with the coverage I pull the stencils 15 minutes after the last coat is applied. Do not leave stencils on for longer than is needed they will end up stuck to the plane. As soon as the paint flashes and appears dry to the eye it is time to pull the stencils. This goes for pulling tape also. Usually when the paint dries it will begin to try to pull the tape up so if you have to go for a second coat be sure to check in the tight corners where you have tape applied or in a curved line. Just lightly press it back down and paint on as usual. Red does this more so than the other colors. If you know to look for this it is really no big deal. If you should forget you might see some over spray in the tight corners where there were some real tight curves. Just keep your eyes peeled.
Now I change to the Blue and paint all my stencils on the tail section. This is a small area so total work time is very small. It is blue going over red so it covers in one coat. I am done in about 1 hour. I am sure this can be done faster. I don't do this for a living so I just take my time and work slow to minimize mistakes.
Now comes the tough part of my paint scheme. The Moon eyes from Dean Moon racing products. There is no stencil available so I cut my own and do some pretty wild looking masking around the area in question. I used white and black for this part.
These two colors were painted with an airbrush. The airbrush is not recommended for this paint. Since we use such small areas it is okay to go for it. The real reason they don't want you to use it is uneven coverage. I just gave it enough pressure to pull the paint out of the tip and it covered nice and smooth. I put the white part down first. It took three coats to cover the blue. Then I put down the black part. I took only one coat. I finished with the black on purpose.
I moved to the nose of the plane. I was going to put a set of twisted checkerboards on the nose, black over red. I taped the checkers off and one coat later presto a perfect set checkers on the nose. Now I am going to paint some thin black lines along the leading edge of the wing and the stab. I taped it off and 30 minutes later the lines are straight looking good. It was nice having the black already mixed up in the airbrush.
Now I let the paint sit for about an hour.
I come back after a sandwich with freshly washed hands and wipe the plane off with the tack cloth twice over the whole airplane. Once I feel it is clean enough I move onto the clear coat. I uncover the canopy, I previously sanded it with 1200 grit to get it real smooth. Yes spray the canopy it will come back very shinny.
Remember there is no sanding prior to clear. You want to touch the plane as little as possible. I wear rubber gloves at all times during the finishing process. This will keep all oils from your hands off the plane.
When it is clean shoot the first coat of clear. I recommend going for a dry coat. I have heard the terms dry coat and wet coat since I got into this Painting airplane stuff. It was a while before I really knew what they were talking about. Well on the touchup gun there will be a mechanism (big screw) that will adjust how much product is being sprayed with the given amount of air. The more you turn it one way the more air there is and the more you turn it the other way the more product comes out. You really can't see it in the air but you can when you apply it to something. I suggest you test on something and get it how you like it before you go for the plane. If this is your first attempt at spraying the dry coat will look rough like very fine sandpaper. It will also dry faster. Move the gun evenly and smoothly along the air frame staying the same distance away from it all times. There will be over spray on the plane in some places. This is hard to avoid with dry coats. Now I let this dry for at least three hours. I now have close to ten hours total time after the three hour dry time. I give it this long so that I can knock off some the over spray before final coat.
Now comes the hardest part of this whole process. I recommend if it is late that you go to bed and do it tomorrow when you are completely rested. If you feel fine after the three hour rest go for it. It will only take about 20 minutes to put down the final coat. If it is dry enough to knock off over spray then you can wipe it one more time with the tack cloth.
Now mix it up just like the can says set the pressure at 40 psi. Do some testing on a board or something smooth. You want this coat to be wet almost wet enough to run. Take your time get it right on the smooth board or what ever you have decided to test on. I usually finish a piece of wood along side of plane for this very step. Now go for it. Put down a smooth coat. Spray the edges first then the flat areas next. One thing that you will notice is that the wet coat will absorb over spray very nicely. It will look like over spray then when you come back later it will be gone. This is called "wetting out." If you are getting this result you are right on the wet/dry mixture. If it won't absorb most of it then you might be too dry. Of course if it runs you are too wet or have too much clear on it. Important; if it does run you cannot wipe the run away like you can with older paints where the clears sits on top of the color. This clear actually attacks into and activates the color so if you wipe a run you will smear your paint underneath. Just get away from it and clear elsewhere and sand it out later. I got big runs on my cowl but I sanded them out later. Once the coat is smooth and wet stand back a smile at what you have created. The really cool thing as that once you put it down wet it dries looking wet. What you see is what you get.
When you purchase your clear coat it would be a very good idea to purchase a can of reducer. This is the equivalent of thinner for lacquer. This clear system cannot use thinner so they have their own stuff called reducer. The clear, by nature is thicker than water and dries very fast. It can be difficult to get it to "flow" out of the gun smoothly. With 10% reducer added it is a dream. The reducer will slow the drying time and the "wet out" is incredible. It helps to thin down the mixture and it will cover in very smooth thin coats. This is a small purchase that can really make this enjoyable.
The paint job is done.
At this point if you want you can blow off buffing it out if it is shinny enough.
If you do plan on buffing it out you will need to wait at least eight hours for the clear to fully cure. I would recommend a full twenty-four hours before starting the quest for the ultimate shine. Always check with you supplier about buffing and how long you should wait to sand it out.
Buffing urethanes is no secret. Wet sand the surface down with 1200 grit paper. Change your paper often for best results. You can go as rough as 1000 but do not go any rougher then that. If you do the clear is so hard it will lose shine. It is called cutting the shine out. The paint store guys will tell you the same thing. After the whole plane is sanded evenly with 1200 come back and sand it out with 2000 wet.
Now you are ready to buff. Buy 3M Perfect It-II compound and polish until you get a good shine. They may have a new compound for it by now. I bought this stuff two years ago. They always seem to come out with new material to improve the process. I used a machine buffer on my last plane and had the whole thing polished in two hours. The sanding of course took longer than that. For the best results an orbital buffer that spins 2000-4000 rpms will bring out that mirror shine like never before. If you do it by hand it will take longer that is all. Just keep rubbing until it shines. If you do buff and sand it out I suggest doing it within one to two days of painting it. If you wait to long the clear will be so hard it will not buff out. The compound will not cut it. If you clean it with Windex or any glass cleaner and the shine wipes off you have not buffed enough. Just keep rubbing.
I hope this helps. If you have any questions just call or write anytime.
I always love to talk airplanes.
Stand back and smile.
Covering with Plastic Film
by John Miller aka JoeBellcrank
Since there are many ways that will work with film covering, I thought that I'd offer a few that work well for me.
Why Plastic film covering may be for you.
First, let's explore why you might want to use a plastic film rather than the traditional Silkspan, Polyspan, dope, or painted finishes. Let me say right up front, that a well executed "Kote" job can really look good, but they usually will not match up to a well done traditional finish. Still, you can expect to get decent appearance points, without all the fuss, and time invested in a painted finish. Plastic films can be a long lasting, serviceable finish with proper application and care. I use them often because I live in an Apt. My neighbors appreciate having less dope smell wafting through the complex, and not having to listen to a compressor.
Another possible advantage is a well done film finish will often weigh less than a painted finish. It will also often take less time, which allows you to be out flying, trimming, and practicing, while the other guys are still painting their planes.
Might I first suggest that anyone new to plastic film covering, get the excellent book on the subject by Higley. Becoming familiar with the techniques as discussed in this book will form a good basis for what I'm going to have to say on the subject. A little study with a book such as this will shorten your learning curve.
I'd also suggest, that if you are absolutely new to film coverings, that you try the various techniques on scrap pieces, and built ups that simulate specific problem areas we'll be discussing. The bare minimum tools required, won't set you back as much as it would if you were trying to do a good paint job. I would suggest the following to get started.
•A 100 pack of single edge razor blades. •An exacto knife. •A bulk pack of no. 11 blades for the Exacto. •A covering iron. •A covering heat gun. •Several pieces of poster board. (used under the covering when cutting.) •A can of Balsarite, or Sigs "Sticksit".A foam brush to apply the Balsarite. •A good light source. (It's always easier when you can see what you are doing.) •Several straight edges, in different lengths.
Additional, or optional items that will make it easier to do a superior job.
•An extra iron with a covering sock. •A small trim iron.A trimming tool. •A self healing cutting mat. •Friskit "rotary" cutters, straight and pinked. •A good pair of scissors. •A smoothing glove. •Several pieces of foam or a couple of blankets to lay on the table to protect the plane and your prep work from damage while you are working on covering it.
Which plastic film covering?
Let's look at the available film coverings for a moment. There are a lot of choices out there, but I would suggest that you only consider the top of the line coverings. Your job will look better, and last longer by using the best. Some of the low temp shrink films will look good for a while, but my experiences show that there's often a delamination that occurs between the clear plastic, and the color/glue over time. Money spent on the best films available, will be money well spent.
My own films of choice are, MonoKote, Coverite Mica Film, and Oracover, or it's successor Ultrakote. These films seem to be much stronger, and longer lasting than the "Econo" brands. Of course, if you're covering a plane that will be used in any kind of sport, combat, or other events where appearance isn't as important as PA, go ahead and save some bucks if you want.
Covering a stunt ship is different.
Most CL stunter film coverings are limited to the flying surfaces, with the fuse painted. This is a good compromise for PA. A bit of attention to the wing/stab/fuse joints will make the change almost seamless. It's also possible to completely cover profiles and full fuse ships with a film. I'll try and cover the methods for both.
In any method of finishing, preparation is always the key to a good finish. Film covering is no exception. Proper sanding of the base is essential. Sand as if you were planning to do a traditional covering. Be sure to use a tack rag prior to apply any covering. Small imperfections will show like a boulder under a film covering. Remember, the covering is the final finish. You won't be able to sand out any imperfections while you are applying the finish as you can with paint
Straight, or traditional film covering.
The traditional film method, would have you apply the film right over the prepped bare wood. This will work, and give a decent workable finish in most cases, but later I'll outline a better, in my opinion, method. One of the problems with this method, helped a bit by the use of Balsarite, is the tendency for the film to "bag up", or get wrinkles, when exposed to a heat source, like the sun. Over time, this can make a film covering look pretty bad. Constant attention, and re-shrinking, can help, but often the heat used will cause more problems later, in the form of gassing under the covering, which causes the film to become loosened from the wood. A small pin hole at the edges can let the gas out as you stick the covering down should this happen to you.
I always apply Balsarite and let it dry before applying any film. It's just that added insurance for me. One, or two coats applied with a foam brush will be what's needed. After the Balsarite has dried, another light sanding and tacking will be helpful.
Balsarite, or Sigs equivalent product, Sticksit, should be definitely applied in the nose area to help prevent oil seepage under the covering.
Covering the flight surfaces before or after they are attached to the fuse.
Some prefer to cover the wing and stab before attaching them to the fuse. The most important consideration, if this is your choice, is to carefully mark and leave the covering off in the areas to be glued.
Some who go this route, prefer to cover from tip to tip, and then make, diamond cutouts, in the area where the glue will be applied. There seems to be some merit to this idea, as the additional strength imparted by the covering continues through the fuselage. The diamond cutouts allow the glue to attach to bare wood rather than the plastic film and its' bond to the wood, which, in most cases, is not as good as a wood to wood glue joint.
It can be said that the strength imparted from plastic films isn't that essential. those who feel this way often cover after joining the flying surfaces to the fuse. This is my preferred method, even though I do believe there is some strength added by the covering.
Fuselage / wing / stab joint.
If you're planning on covering the entire plane with plastic film, and your fillets are either nonexistent, or very small, you should first address the important joint where the fuse and wing/stab meet. A bit of attention here will pay important benefits in the future.
If you are using small fillets, use your favorite method to apply them. With no fillets, the job may be a bit easier.
After applying and lightly sanding Balsarite, cut a strip of film long enough to go from the leading edge to the trailing edge, with some to spare, and wide enough to extend at least 1/4" out onto the wing, and up on the fuselage. Start on the bottom. Starting at the bottom surface will hide your beginning efforts, should you make an error. Starting on the bottom also puts the all important lap joint slightly on the underside of the surface, where it's not as noticeable.
In the case of no fillets, crease the film lengthwise. Start at the high point, and use the tip of your iron, or your trim iron with the flat blade, and stick the crease right into the area where the flight surfaces and the fuse join. Work out onto the flat sides of the strip, and seal them down real good. Work your way back to the trailing edge, and forward to slightly wrap around the leading edge. Make sure this area is sealed down tight.
With small fillets, you can omit the crease, and use the curved sealing head, or the back of the tip of the full sized iron.
The trailing edge.
Cut a strip slightly longer than the wing panel, and about 1/4" wider than the trailing edge where the hinges will later be installed.
Iron on the flat first, the roll the edges over, on the top and bottom of the trailing edge. There should be at least 1/8" of covering on the top and bottom of the trailing edge.
The wing and stab.
The wing and stab cover almost identical, so what is said should pretty well apply to either.
Cut a piece of film that's at least 6 inches longer, and wider than the surface to be covered. Don't be cheap and scrimp on this as you'll need the excess to grip as you heat form the tips, and leading, edges.
Turn the plane on it's back so you can cover the bottom of the wing first. Set your plane on your covered table with at least 3/4 of the wing supported. (Here's where those blankets or pieces of foam come in handy.)
With your full sized iron, tack, ( touch with the iron long enough to activate the heat sensitive glue.) 3 or 4 places on the wing panel, next to the center of the strip applied in the joint previously. In the case where you have a small fillet, set the edge where the curve starts, and tack in a similar manner.You want the wing tip free, and hanging over the edge of the table for this step. With your free hand, grip the end of the film, near the tip, and put some tension while applying heat from your heat gun near the wing tip. Continue to pull as the film gets soft from the heat. Instead of shrinking, the film will stretch. Continue with the pulling heating and stretching until you have formed the curves at the tip. This is called heat forming . If you continue to work with the heat gun and stretching until you get to a point somewhat past the center of the wing tip, you should, with practice, be able to make a seam without any puckering at all. The heat forming also slightly tacks the formed tip in place, but it will be necessary to seal it down solidly later.
At the trailing edge, use your free hand and put a little tension at the center of the span. Tack with your iron. Do the same thing at three or four more spots, before moving to the leading edge.
Again, use your free hand, at the center of the excess at the leading edge. Use your heat gun and in a similar manner as the tips, heat form the curve over the leading edge. Start at the center, and work your way to the root and tip. A light rubbing with a soft cloth right after applying the heat, will tack the leading edge into place. You can also stretch a little past the center of the leading edge, similar to the tip.
Once all the heat forming and tacking is done, you can iron the covering permanently into place. Start by tacking between the previous tacks, then go for the whole thing and seal it down solidly.
•At the trailing edge, pay some extra attention to the overlap. Make sure it's sealed tight. •Use a new single edge razor, or your trimming tool and trim the excess from the surface. •Turn the plane upright and do the top of the same wing panel, in the same way.
You can either do the other wing panel in the same way, or use your heat gun to shrink the covering tight on the first panel. In either case, when doing the final shrink, work a little on one side, and then the other to try and keep warps from being shrunk into the panel. If you do get any warps, they can be removed with a little twisting and heating later.
Some like to seal the covering to the leading and trailing edge, as well as the cap strips at this point. I don't prefer to do this as it makes it more difficult to remove warps that may occur in the future. I also feel that unless you've done a superior job preparing the leading and trailing edge surfaces, any imperfections in the structure will be more apparent if these areas are sealed down tight.
Flaps and elevators.
Flaps and elevators, when not built up, are probably one of the most difficult areas to do and have look right over time. A careful bit of work here, and they'll look good. Hurry it up, and you'll be seeing bubbles and loose covering sometime in the future. Of course, you've done the normal prep work, sanding, tack ragging, and Balsarite. But there're some additional small steps to do when applying the film.
You will need to cover the pockets you sanded for the hinge barrels. You'll also need to cover the flat ends and tips of the flap. Since I like to have my flaps end with a square 1/8" wide tip at the trailing edge., I cut a strip of film at least 3/8" wide and apply it to this area. I roll the 1/8" overage onto the bottom and the top of the flap or elevator. Seal the edges down tight.
For the flat ends, cut a strip in a similar manner and stick the center and then the entire flat. Roll the excess as you did the trailing edge.
For the hinge pockets, it can be a little dicey. the idea is to stick the film onto the longest flat, then to each side, leaving the overage sticking above and below the pocket. Use your razor and slice the crease, formed when you stuck the sides of the pockets, to the top of the surface. Use your iron, and seal these little tabs tightly into place. Pay attention at the 45 degree leading edge.
Now we can cover the flat areas, best done by once again cutting a strip of film wider, and longer than the surface. Start once again on the bottom surface.
Lay the flap. or the stab, as they cover in a similar way, on a clean flat surface. Lay the film on top, carefully centering the film over the part. Use your iron, sock covered if you have it, in the center of the flap or elevator. Work the covering down from the center, to each side, and out to the tip. The idea is to not trap any of the gassing under the covering as you stick it down. Turn the surface 180 degrees, and in the same way, work out to the root. Be careful with the heat, as you can still get some gassing if you're not careful. Next, we need to do the 45 degree angle at the leading edge. Once that is done, cut and remove the covering from the hinge pockets. trim them tight, and seal the edges well. Turn the surface over, and continue the covering onto the other 45 degree surface. Once you are sure that every thing is stuck down tight, Use your razor, or trimmer, and trim all the excess off.
Turn the part over, and do the other side in the same manner. Flaps and elevators are almost identical in procedure.
This section is used for larger fillets, especially when you are painting the fuse. It can also be used with some minor variations when both the flying surfaces and fuse are film covered. In this case, you will paint the fillet with a matching color. LusterKote works for me in this case.
I like to pink the edge of the covering adjacent to the fuse for this method. I cover the wing as before, then form the fillets. You can use epoxylight, epoxy and micro balloons, leather fillets, or balsa fillets to form the fillets.
Before installing the fillets, take the time to tape a line about 1/8" further onto the wing than the edge of the fillet. This way you won't get glue onto the finished surface of the wing. If you covered your wing before installing it, you would do this also before gluing it into place.
Install your fillets. After the fillets are in place, remove the tape, and re-tape about 1/16" to 1/8" further out. sand the edge to a feather edge.Other than covering the fillet with coating of spot putty, the fillets are ready to be painted.
Covering the fuselage.
If you have chosen to cover the fuselage with film, here is the method to use.
It's important to have all the lap joints going towards the bottom of the plane, as well as toward the rear of the plane. This acts in the same manner as a shingle, and resists oil seepage. The exception here is the nose ring. Stick it into place first. Make it about 1/8" to 1/4" larger than the nose ring itself. Once the flats are stuck down tight, you can make slices every 1/4 inch around the radius, now, stick these tabs down very tightly.
Start on the bottom of the fuse, and from the rear, use the largest pieces you can to minimize the laps.
At all times, try to start in the middle of the piece you want to stick down to avoid gassing the glue with the heat. Once all the bottom is done, roll the edges up the side, approximately 1/4". Make sure the covering is stuck tight, especially at the edges.
The side pieces can now be applied. One piece if possible, but most of the time, I'll use two pieces, with the lap at the high point of the wing. Again start at the middle and work out towards the edges. the trimmed bottom edges are finished off flush with the bottom if possible.
Lastly, comes the top piece. Pay some attention here, as this is what will be seen most of the time. Due to the compound shape of the top blocks, it's best, in most cases, to do a bit of planning before applying any covering. If possible, figure where your trim lines will be going, and make your laps in a place that the trim will cover them.
Depending on the shapes, it's sometimes necessary to do the turtle deck in two pieces with a seam at the top center, running lengthwise. Again, work from the back forward. Make your lap at the back edge of the cockpit if possible. Sometimes it's necessary to use the heat gun and do a little heat forming before ironing the covering down. The downside of this happening is that it will be more difficult to avoid gassing the glue, so be careful. With a little work and some attention to detail, the fuse is done.
Painting the fuselage.
Use your favorite method to prep the fuse for paint. Most paints with the possible exception of water based paints will adhere sufficiently to sanded or scuffed film covering, but the best adhesion comes with paints that are formulated to adhere tightly to any surface. These include Epoxy paints, LusterKote and it's kin, and Enamels. Be careful with these paints as they are not lightweights. Make sure the film covered surfaces are masked off to avoid getting any paints where you don't want it to be.
A better film covering method.
I mentioned earlier that there was a better method to use for film coverings. It will work much better than film on bare wood, won't bag up, loosen, or cause problems down the road.
First, precover the flying surfaces with silkspan, silk, or Sig Koverall. Koverall as a precovering is the strongest, and also the heaviest of the options, but the strength is unbelievable.
The chosen precovering should be coated with one or two coats of thinned dope, or better yet, Balsarite, thinned 50-50. The fuse, if you are going to cover with film would be treated the same way.
The beauty of this method allows the gasses to bleed off easily, due to the porosity of the substrate. The film adheres to the substrate, and the substrate stabilizes the film. I have seen planes several years old which have never had their film sag or bag up. They are still as tight and smooth as the day they were first covered. On some of these planes, you have to look very close to tell that they are film covered.
In addition to all this, the covering winds up being stronger than either layer alone. I believe it's a win win situation.
Attaching the film.
The method of film attachment is slightly different than the traditional method outlined above. But it's sufficiently similar, that with a few minor changes much of the earlier techniques will work quite well with it. The biggest difference is when covering the wing panels.
Start by tacking the edges around the entire perimeter. Once tacked, use your iron, covered with a iron sock if you have one, and start in the center of the middle open bay. Work your way out to the rib caps. Iron down the rib cap, and move out into the middle of the next bay. Stop at the last bay next to the tip, and where the center sheeting begins next to the fuselage. We'll still heat form the tip to get the best appearance. Once all the bays are sealed down, add some additional tacks to the leading and trailing edge. Use your heat gun and some tension from your free hand to shrink and form the leading, and trailing edges. The heat from the gun will slightly tack the surface to the substrate. Use your iron to finish sticking the film to the substrate.
If you did it right, it will be stuck to the substrate. there will be no sagging or bubbling. the surface will be smooth, and will stay tight and smooth.
This works quite well over solid balsa surfaces as well. The solid surfaces will be smooth and not wrinkle or sag. Fuselages will also look as good as the flaps if you do it right.
Attention to details.
Another advantage occurs when you do your trim. With the traditional method, one usually either paints on the trim, or sticks colored film onto the base film for the trim. The problem with this is that there is no place for the gassing to go, so bubbles come up and even after the pin pricks and re-sticking, you can always see where they occurred.
With this method, and a little pre-planning with your trim scheme, you can leave areas free of the film, and apply the trim colors right to the substrate. All that is needed is to use a minimum of 1/8" laps. With intricate trim schemes, it's again best to work from the back to the front, as it keeps the laps facing away from the airstream.
Transparent films over these substrates look an awful lot like dyed dope finishes. Weight build up can still be less to about the same as a traditional painted finish.
There it is. Most of what I know about using film coverings. I may never make Concours, but I often am complimented on my finishes. I'm sure there are others methods as well as tips from others to add to this, and I hope that some of you find it useful.
The Legacy pictured here has been crashed, pancaked into the asphalt, repaired and is now over a year old. It was covered using transparent MonoKote over silkspan, and the covering is still tight, no wrinkles, bags, or sags. During the crash, a small tear resulted when the force of the impact broke the outboard stab leading edge about two inches from the fuse joint. I repaired the tear using the old method, Ambroid glue.
I'm wondering why everything is spinning around?