Hole repair.....STILL

The million dollar question......do I trim the raggedy edges? Or not?

And as for the previous thread with the MEK fiasco..... Turns out I have an undocumented paint job on the bird. Yay me. NOT. Obviously some sort of -thane paint.... Ran or Aero. after wet sanding through the Thane coat, MEK did the job.Do I need to wet sane the whole thing to shoot it? I think I do. Have the colors picked out though... :-)

Happy New Year all.... Finally getting the patches Poly-Tak'ed on today and all the way into silver, fingers crossed. -4 outside, 55 in garage. If youre close, stop on in, free inhalation buzz.

Yes, trim away the ragged fabric to the point where you have a flat trasition.
Apply your patch using at least 2 inch overlap. Use polytack.
If you have trouble getting your patch to stay in place while you tack it down, use a curved needle and a few stitches.
Shrink fabric with iron.
Apply finish tapes around edges of the patch. Because it is in the slip stream use at least a 2 inch overlap finish tape. (4 inches wide - You can make your own finish tapes from regular fabric.)
Apply Polybrush and polyspray.
Wet sand.
Apply finish coats.
Go fly.

Because this is a large repair you may want to consider doing the whole bay between ribs. It just depends on how picky you are on the final finish. If it were me, I'd do the small patch and go fly.

John

The poly-fibre manual says under the heading Repairing Poly-Tone: Trim the ragged parts out of the hole. Unless you could reach inside the wing to press the ragged parts to the patch so they would adhear, they will just be laying loose in there and my guess is that's one reason they say to trim the ragged edges. Is that a false rib in the center of the hole? Not broke is it? Take care, Jim Chuk

Jim, yes that is a false rib.. Not broken.

John, is finish tape necessary with the 2" overlap (frame) around the hole? If so, SOB, I gotta wet sand more to get the margins for the finish tape. And yes, I am like you, going to do the small patch and go freeze my tail off slipping the surly bonds. Good, cold, dense Canadian High Pressure over area, and I am stuck in garage patching the air machine. Grrrrrrrrrrrrr

A tip on final finish. If you spray Aerothane on a repair like that, the overspray will be very noticable as the paint droplets on the overspray will not flow and blend. John's suggestion about sprayng a whole bay will help hide the edge if you use masking tape but if no one else sees the edge, it will still be the only thing you see when you look at the repair. I have been told of a technique and have tried it on some small repairs with acceptable results. It is basically this. Use two guns. One filled with your finish color, the other filled with reducer. After you spray each coat of color, spray the overspray lightly with the reducer. It will flatten and blend the droplets. It will pretty well hide the margins. Also I have tried with good results the old Acrylic Lacquer technique of color sanding with very fine sandpaper - progressing to 2000 grit, then a rubbing compound followed by a glazing compound. On the fabric I have always done it by hand because I have worried about machine polishing rubbing through the color at the pinked edges of the finish tapes.
Lowell