Covering Airframe with OS Mylar Film By Jeff Annis

The process that I use for covering with OS film is as follows. Shelving paper which has a light adhesive similar to post-it notes is stuck to a plywood board. The opposite side has a dull bond paper-like finish (not shiny) so that the film doesn’t stick to the paper and the film is easy to slide on the surface for pulling out the wrinkles. You could also attach this paper to a countertop and remove it afterward. Roll out OS film on this paper surface and cut off what you need from the roll with a new sharp razor blade. Score the film first, then will tear off easily along the score line. Roll out the film so it makes contact with the paper first because static force is very strong. Then can pull it off into a ball and work with your fingers for several minutes to crinkle it well making sure you don’t pop any of the air bubbles. This will kill off most of the static charge.

 Now you can spread the film out on the paper and remove all wrinkles. I spray the frame outside with 3M 77 well. Let dry for a few minutes and then bring inside. Center the frame with the film and slowly drop onto the film. Go around the frame and push to make sure you have a good bond with the film and frame. Now lift up one corner to break the suction first then slowly lift the frame off the paper. 

You are now ready to cover. Prop the frame up a bit at both ends with blocks. Lay out the wing frame upside down on the film. An adhesive recommended by Mike Kirda that works very well is Best Rubber Cement thinned 10:1 or 8:1 with Bestine Solvent Thinner. Start with the leading or trailing edge running a brush along the outside of the spar and wick thinned adhesive solution to get the spar to stick to the film with capillary action. Don’t be afraid to get plenty wet. With microfilm, in the past I would a mix spit and water for an adhesive. Let dry and then cut with a low wattage soldering (25W) or cautery pen.    

Dihedral joints are put in by scoring the joint location a bit with a razor blade from the top through the film and slowly bend the tip up. Wood will crack along this line. I hold center wing spars down with a couple of pennies or dime weights and block up the tips to the proper angle. Wick in some glue or CA to glue the dihedral joints and remove from the surface when dry. Baggy film at the dihedral joints is bonded to the underside of the rib by wicking thinned adhesive. Once bonded to the rib, any other bagging film can be removed by running a brush along the top of the rib. The capillary action will suck up any other baggy film. This process has worked successfully for me over the last 13 years since returning to the hobby after a 30 lapse with prior experience being microfilm covering. Recent models covered using this process include F1D, F1L, mini- stick, Intermediate Stick, A6, Limited Penny Plane, A-ROG, and Hand Launch Stick.