Any fabric paint gurus on here...? restoration time

[C5Engineer 1170]

Well my wings are just about complete after a total recover. They are being painted with Randolph Insignia White dope. The rest of the my airplane is the original paint. It appears to be some sort of Aerothane. It's brittle, won't rejuvenate (MEK barely phases it), and has a fairly shiny finish. I have some ringworm going on on the back of the fuse and a small tear I need to patch. The A&P that did my wings said I would not be able to spray dope on the old finish. He recommended I just go to a reputable paint shop and get some auto polyurethane and match it and spray it. I'm thinking this will work.

Any ideas on the best way to tackle the ringworm? I sanded on some of it and it blends out but I need to way to build it back up so the finish is smooth. There's a few small coin size spots where the paint has flaked off all the way to bare fabric. I punch tested it in a few places and the fabric is still good. I'm not looking for a show plane here just trying to get a fresh coat of paint on it on the cheap. I was hoping to just spray the back of fuse and the tail feathers but not opposed to little extra work and repainting the whole fuse. I have access to spray equipment.

So now that I'm done rambling do we have any restoration guys on here? Thoughts on the simplest way to breathe some new life into my fuse? My wings are brand new so hate to put them on a sorry looking fuselage.

Thanks!

[akflyer 1427]

First is to figure what you have now.  If it is aerothane I can tell you how to fix it straight out of the polyfiber manual.  If it is dope, I think the proces will be pretty close.  I will call a buddy today and see what he has to say.  He has been doing this shit for 35 years and has restored alot of dope planes.

[84KF 4]

What Leni says...."the polyfiber manual."

If they still use the same info in the recent version, there will be an excellent chapter on refinishing dopes and paints.

It's all about adhesion and flexibility. First it has to attach itself to the fabric, then it need to withstand flexing without cracking. Stitts products will achieve chemical adhesion to each other (very strong), most everything else sticks through mechanical adhesion.... not the best way to keep paint on fabric.

If you choose to refinish the existing finish, besides 100 other things, one needs to make sure the surface is free of silicones (wax,etc...), and well wet sanded with 320/400 grit. sandpaper. 3M makes good stuff.

Watch out for high spots such as rib lace, stringers, and tape edges...very easy to sand right through the fabric or start a frayed edge. Never sand down to the fabric...., Dacron and sandpaper don't mix.

I could go on , but (as Leni said) the Stitts PolyFiber installation instruction tells all.

I will call a buddy today and see what he has to say.  He has been doing this shit for 35 years and has restored alot of dope planes."  Rookie !! HAHA   

[84KF 4]

Here are some pics of what a REAL bad finish will do, due to lack of adhesion. Using a plastic paint scraper I was able to "strip" loose paint (?) right down to the fabric, which was doped with nitrate. A few coats of buteryate and a few yards  of new finish tape  got it to the point in the last 2 pics.

[C5Engineer 1170]

It was originally painted in Ranthane. I have the Poly manual it does not address this type of work. All I did was sand down some ring worm. I just want to spray a fresh coat of paint on it. I'm wondering what would be the best way to do this. I don't really want to spray it with Aerothane again if I don't have to. My wings were done with dope so trying to match them as close as I can.

[84KF 4]

I'll go out on a limb here and offer a suggestion. I have done this in the past and had good results, but each situation can be different due to the  type of finish one is trying to repair/repaint. It all depends on the compatibility of the materials being used. Some will cause lifting and wrinkling of the existing finish, some do not.

  For the ringworm repair, (and most fabric repairs) it's best to sand the finish down to the first layer of dope. I would say "down to fabric", but you don't want to damage it. It's easy to do. Extend out some distance from the repair so you don't end upwith a big "dip" in the finish  Masking the area is a good idea when done sanding.

Using Polyspray or Non-Taughnting butyrate dope spray, or even brush a light well thinned coat of the repair..... and let it dry a few minutes.   This is when you find out if there is a compatibilty problem...  This could depend on what thinners and such are being used.... MEK? or Randolphs thinner?, or Polyfiber reducer?  etc...

Anyway, if it dries ok, put on a few more coats, and wetsand with #400 3M Wet-or-Dry

Brushing can take many coats, many sandings, to keep the brush strokes from showing but the idea is to resurface the repair with the solids in the dopes left after the fluids evaporate, so it takes time to build up. Spraying is best..., with a touch-up size gun. Go for a nice wet coat so it "flows" out, but watch for runs. Dry. Sand. Repeat as necessary.

It would help to know what the covering process was/is originally.....Stitts (Polyfiber), Ceconite?

[C5Engineer 1170]

Thanks for the info! As best as I know the original fabric was the Light Aero that came with the Avid Kits back in the day. It was super light and not certified.

[84KF 4]

I am not familiar with "Light Aero..." .  I'll assume it starts with a dacron fabric. The question then is what type of dope(s) the process uses. I work mostly with nitratebutyrate or Stitts. Never used any of the spinoffs or water based stuff. Nitratebutyrate will finish out the best..., being organic, all coats can be sanded to perfection. You can't sand Stitts Polybrush, and even a sprayed coat will never be a smooth as a sanded coat of butyrate. With cottennitratebutyrate you can sand seams and tape edges invisible.

Stitts will last forever..., 20-30 years. Doesn't crack or shrink with age. The aircraft airframe and structures will start to rust or develop corrosion spots before the fabric needs to be replaced

The MOST perfect finish will be found on an aircraft covered with cotton, and finished with nitrate and butyrate.

Doped cotton fabric takes to sanding great.  Cotton and linen are the only fabrics that hold true dope well. They are used on dacron but it's not the best combination, starting with the initial (poor) adhesion of the dope to the dacron.