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Old 02-01-2018 | 09:37 AM
  #10  
GREG DOE
 
Joined: Jul 2005
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From: , TN
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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