Over the last four (4) decades, the choices of covering materials for models have expanded steadily and R/C modelers have quickly adopted the new methods. Modelers involved in other disciplines, especially controlline stunt, are not as eager to change their methods of finishing models. There must be a reason for this. The primary reasons are that it is easy, cheap, fun, and above all, beautiful. Silkspan, the primary covering material, is lightweight, accepts nearly all paints readily, and will never sag, bubble or wrinkle. It goes on just as easily over either sheeted structures or open framework.
Silkspan is primarily used on smaller models like Old Timers, 1/2A glow and small electrics, but it is also an excellent surface preparation for sheeted surfaces even on giant scale warbirds. There are two (2) primary disadvantages to using silkspan; it is easier to tear or puncture than plastic coverings and requires much more time and effort to finish.
R/C modelers could learn a few things about finishing their airplanes from controlline modelers. These people can make the most phenomenal finishes and keep them light enough so that the model is competitive. Maybe this is in part the reason that controlline stunt models are scored on appearance and R/C pattern planes are not.
The stunt community in general frowns upon anything that irons on. The purpose of covering the balsa structure with silkspan is to hide the grain, not fill it, and to add strength. It makes a tremendous difference in strength. According to Windy Urtknowski, a guru of stunt model finishing, there is no way to fill balsa grain at an effective weight. He says he has tried covering with glue and sanding it off, but that the grain reveals again after sitting in the sun for a while.
The steps required to achieve that fabulous finish are:
The ultimate goal of this process is to make all of the surfaces as flat as possible then use the dope and silkspan to make it smooth. The trick up to this point is to use as little thinner as possible in the mix. Thinner changes the shape of the wood taking away from the flatness of the wood and requiring more sanding.
The trick to finding flaws is to sand in a room with only one light source. Hold the model up to the light and bounce the light off the working surface on at an oblique angle. This will make even he slightest flaw visible. This technique is called candling. All flaws must be corrected at this point; otherwise they will be even more visible after the color coat is applied.
Silver primer is very important to an award winning finish, especially when translucent paints, such as candy apple automotive paints, are used.
Normally, the reaction when the silver is sanded will be frustration. Every flaw is highlighted. Sand off as much of this silver as possible and correct all flaws with sanding sealer.
Note: Do not spray different colors over each other. This adds weight and makes the color harder to apply. For example, do not paint the entire surface white and put blue trim over the white parts. Mask the areas that are to be painted white and spray it. Remove the masking and allow this coat to dry thoroughly. Mask over the white and spray the blue trim. The silver dope is a perfect base for all colors and saves weight. Finishing this way takes a lot of work and time but the results are incredible.
This covering technique is lighter than most of the plastic film coverings, will never wrinkle, and is quite easy although time consuming to do. The results that can be achieved from this method are incredible and unattainable with film coverings.
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