Ceconite rejuvenation

Big Ed

N50247 - '79 Super D
Joined
Jul 20, 2020
Messages
1,938
Location
Tampa, FL
Trying to bring the original factory dope finish on my 78 Super Decathlon back from the dead. Starting with the fuselage, because it looks the worst. Plan is to strip the bad spots and along the longerons/stringers, add reinforcing tapes to areas of wear, then rejuvenate and repaint with dope.

Some initial photos of the bad spots:

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You do need some work.
I have never had any luck rejuvenating old dope. I wind up with fabric over the bad spots. I think others have been successful. Try one spot at a time, at first.
 
Initial 12 hour session .... got to hangar at dinner and worked until dawn. Stripped top and right side of fuselage and added tapes. Photos of stripped areas first:

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Second half of session: patches and tapes. Used 1" tape on the middle stringers. It did not lay very flat. Edges are curled up pretty bad. Hoping I can fix that with iron and parchment paper today.

Reinforcements at door area were badly needed. Some of the fabric seems like it is getting wet on the back side, which affects adhesion. Also, the old factory nitrate glue is not nearly as strong as the Super Seam.

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A few comments on process so far.

1. You know that thing when you pull a thread on a sweater, and before you know it you have a pile of yarn and a huge hole in the sweater. That happens with dope too.

2. Clearly my approach has changed from fixing small spots and rejuvenating to stripping the compromised areas. After seeing what the fabric looks like underneath, and how poorly the dope adheres once broken, I think that will work out better. I will still spray a coat of rejuvenator, but the intent will be to stabilize the areas where the finish is still good.

3. I tried several stripping methods, but the one that works best is a moderately sharpened paint scraper. Once you learn the technique for getting under the film sheet, you can strip large areas very quickly. You have to be careful not to go too far, unless you want to repaint the whole thing. I probably could have stripped the entire left side of the fuselage in another hour. The hardest part is the areas directly on the longerons. I had to use thinner there, which takes a while and makes a mess.
 
In hindsight I think the tapes on stringers might have been unnecessary. On the other side of the fuselage, I might try the recommended rejuvenation method of sanding the cracks, filling, rejuvenating, and painting. May depend on how well I can get those 1" tapes to iron out. Right now they look like garbage. Gonna give it a shot in the morning.

I also decided I am definitely getting the $40 vinyl N-numbers from Sportys. Pretty sure an hour of my time is worth more than $40, much less 5-10 hours to tape the numbers.

Complicating things is that Florida weather has started to turn. High 80's this weekend. I was really hoping to get this project done during the winter. Unfortunately lost the month of January to COVID and took a bit to get caught up on work.
 
The Stwarts system claims to be able to be used on all fabric systems for repairs, you may want to give them a call. There glue is very easy to work with.
 
Ed, check out Aerographics for your N numbers. They have a big selection of styles, block, round and semi round, straight, slantled numbers and also have stencils if needed. Sporty's only sells one style, that is slanted.
 
Ed,

Is it possible that you might be better off just stripping all of the paint and tapes, reapplying the tapes and spraying the whole fuselage from scratch? Are the tailfeathers and wings ok?

It's going to look awesome when it's done and you're motivating the hell out of me to get to work on my project!
Bart
 
Made some good process yesterday.

Was able to mostly iron down the 1" tapes, though the edge still looks crappy. Very disappointing. Should have gone with pinked. OTOH the 2" straight edge tapes are much nicer, and IMO come out better and faster than the pinked 2".

I went ahead and stripped the problem areas on the top and left side. I did not strip the stringers on the left side to put tapes on. Unfortunately I am running out of time because of some events in April, and that would set me back at least 2 full days of working. That irks me a bit because the left side gets more of a beating from prop wash when flying acro. But this is not really a long term solution anyways, just a few years at most, and right now that area is not cracking very much.

Hoping to shoot rejuvenator by mid-week and be spraying top coats by the weekend.

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I have had lousy luck with straight tapes - but the guy who did my Dec in 1992 used them and they are all still stuck where he put them.
 
The 2" straights are great. Looks like they were woven at that width, so the edge is clean and sharp and lays down flat with minimal finicking. The 1" are cut from wider strips, and they are abysmal. The only reason I tried to use the 1" on the stringers was to minimize the amount of stripping. If I had it to do again, I would use the 2" straight or pinked. Areas not directly on structure are really easy to strip quickly by getting a paint scraper between the film and fabric; that extra 1/2" on each side would take no time at all, maybe 5 minutes per stringer.
 
Brush coat of nitrate. I should have read the instructions better. Tapes were supposed to be fastened with nitrate dope, not super seam. Duh. No wonder it was such a mess. But those dang tapes are NOT coming off.

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Steps remaining:
  1. Spray 2 coats of nitrate on repaired areas. (may consider brushing to minimize overspray)
  2. Wash, degrease, and scuff sand.
  3. Mask.
  4. Spray rejuvenator and wait 2 days.
  5. Spray 3 coats of clear and 2 coats of silver on repairs to build up.
  6. Wet sand.
  7. Spray 2 coats of silver on whole fuselage.
  8. Wet sand.
  9. Spray 2 coats of white.
  10. Mask N-number.
  11. Spray yellow.
  12. Mask stripes.
  13. Spray blue.
 
Ok, I am in way over my head. Started scraping loose dope, and the next thing I know my fuselage top and sides are bare fabric.

Fabric looks in good shape except for a few small holes. Belly is still doped. I might pull off the tapes and replace. I might also strip the V-stab.

Should I try to build back up with dope? Or should I find someone to paint in another system?

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