Was asked to post this--reluctant because JKs way is simple, and works. (And I've described this here a couple times before.) My method is more work, tedious, but toward the goal of a wrinkle-free patch that can also follow the shape of a wing curve, for example. Starts with harvesting patch squares when you cover a wing or anything. Capture a supply of patch film on various squares of light card stock--3x5" index cards cut up into whatever sizes you want. Use tiny line of glue stick around card edges to achieve 1/16" wide border of stickiness around 4 edges, or any two opposite edges would work too. Flop the card on top of flattest, smoothest film you can create. (For me, that means right after burning an outline structure from off my covering jig.) Store these card carriers until needed.
Come patch time:
1. Cut a domestic tissue square to cover part of the film carrier (card.) The tissue square or rectangle is to be slightly bigger than intended size of the film patch, but also smaller than the borders of carrier. Japanese tissue doesn't work quite so well, for some reason. Flexible, non-grainy domestic tissue works well.
2. Spritz water all over face of film. Place dry tissue square on film. It should stick with enough water tension.
3. Spritz more water over top of tissue, which is now the top part of sandwich.
4. Cut out the needed size square of film/wet tissue sandwich with 4 straight, firm slices using sharp stiff razor, cutting inside the tissue/film borders to the size of actual patch. A small straight edge held down very firmly holds the sandwich together and keeps film unwrinkled. If the tissue starts to dry before you get all 4 cuts, water spray again. Be sure the glued border of the card carrier is not intersecting any part of intended patch film, or you may have to start over.
5 Peel wet tissue/film sandwich off of carrier. Spritz water on film side.
6. Place film/tissue sandwich on damage hole (for small patches.) Touch border areas to encourage water tension. Tissue should eventually curl up and/or begin to separate from film (in 20 minutes or so.) For big patches, consider supporting/creating the correct shape or relief underneath area to be patched. For example, sometimes a pillow's curve is good support and shape for F1d wing curvature. The wet tissue can conform to whatever curve or flatness desired, but the problem is water weight; therefore support under the airframe is needed for big patches. (If needed patch is almost the whole wing chord of an F1d, a DRY patch method would probably be better.)
Anything thicker than OS film will need stickier adhesion than just water, but I have never lost a Y2K2 patch using just water. I have lost a couple OS film patches due to being too sparse about how much (rather how little) patch overlap I allowed over the hole damage. If nervous, use whatever favorite very thinned adhesive around patch joint edges. A quick touch using squirrel brush will easily wick adhesive into joint (preferably after drying.)
Mark B
Received on Mon Feb 04 2013 - 13:59:59 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:47 CET