aircraft coveering

[N96337]

Re: aircraft coveering

All of the solvents involved with the glue and the other products are harmful, but until you get to the Polyurethane paint, they can be handled by proper ventilation and a charcoal respirator. Once you talk about Aerothane or any of the other solvent borne polyurethanes, that's a whole new ball game.
This isn't meant to be a slam of Polyfiber or any of the other solvent borne systems. Like I said before, Polyfiber is a great system and I've used it for years! The main problem is that they don't quite tell you all that you really should know, nor emphasize quite enough, about the safety aspects of using it. Usually those classes are taught by people that don't quite understand all the "ins and outs" of some of the hazards. I know I sure didn't for way too long!
I've been painting for over 30 years (custom), and for a long time, figured I was young and bullet proof. Then I started to get sick....and about the time it got pretty unhandy to be sick all the time, I met a guy who was well known in the custom paint world, that manufactured all his own polyurethane paints. He was teaching a class that I was taking on some custom use of his paint. He explained about the catalysts used and the results of them being exposed to our body parts.
If you do nothing else, sit down with the paint and catalyst (or hardner...whatever you'd like to call it) and read what's in there!! IF you see anything like an isocyanide, you NEED a full suit and pressure, fresh air breathing system! PERIOD!!! This isn't something you're going to get around. It enters your body and stays there forever...so it's like filling a cup with water... for a while, you can pour water in there with nothing coming out. Then one day, the "cup runneth over".....and alot happens! You wont recover completely ever. Period. Been there, done that. Some people get by for a long time, others don't. I've personally seen a guy fall over and die from the exposure of one painting session when he wasn't properly protected...on the other hand, I've seen people go for years without any apparent serious problems. How much of a gambler are you? Think not only of yourself as exposed, but also consider who else you expose by the fumes leaving the place you're painting.... people, pets, etc.
One thing we learned in that class was that the most dangerous time for exposure in the life of a catalyzed paint is when you're going to mix it. At that time, the catalyst molecules are "looking" for somewhere to be...and they're attracted to moisture...and we're made up of mostly moisture. Another bad time is while the paint is drying, as it's "gassing out" alot of the catalyst. It will enter first through your soft tissue..ears, nose, armpits, etc.... so spend a few bucks and get a full suit (I paid $40 for my last one) and cover up! Charcoal respirators will not protect you from an isocyanate or any of it's derivatives.
It's not that expensive to guard against problems, and it's sure alot cheaper in more ways than one, than a trip to the hospital or the damage you can do to your, or someone else's body if you don't.
I'm a fan of the waterborne polyurethanes, as they contain water as a carrier, thus attracting the isocyanates to it, instead of you. Do I still wear the full suit and breather? You betcha!! I also have a waterfall over the outlet of my paint booth exhaust fan, which takes care of any that makes it out of the booth when I'm working. It wasn't expensive...all it takes is a good sprinkler head positioned right.
Good luck, and please, be careful!
John

[Pearson]

Re: aircraft coveering

Where does the water go?

[Leenicklas]

Re: aircraft coveering

As I undersstand it, the "fabric" for both systems is the same or at least quite similar; heat is used to activate the glue for attaching the material and a housold iron is used to shrink the material. The main diifference is the glue, paint and other products involved in the process. Am I correct? thanks for your input

[skyboltone]

Re: aircraft coveering

It's certainly not PC but I'm pretty much a "screw the earth" kinda guy when it comes to environmental activism. But catalyzed linear polyurethanes are deadly. I am aware of more one fatal due to the stuff being used in my industry before it became as closely controlled as it is today. The guy had been warned of the hazards but chose to ignore them and wore a wet rag around his face while spraying the stuff on an iron railing around a stairwell. Even when put on a respirator in the hospital they couldn't keep him alive. I think I'd rather wrestle salt water crocs. It's over quicker.

I've never covered an airplane but when I do it will be Stewart Systems. That's just an opinion. I don't have any idea in the world which of the various systems is the best. I don't think Nitrate/Butyrate dopes are any where near as dangerous as the new finishes, but they won't make you any smarter when you breath the fumes over a period of time. I recently got a quote from Stewart for all the stuff needed to cover a Stinson 108-2. With fabric and every single grommet and screw it came to just over $3K. Try that with Randolf Dope.

[swoeric]

Re: aircraft coveering

steve posted some prlim details about the seminar i was talking about...you wont find better knowledge, experience and tools in one place for the price....


7th Annual Piper Restoration Seminar in Graham, Texas

The 7th annual Piper Restoration Seminar will be held on February 18-24th at Pierce Aero in Graham, Texas. This event is best described as a three ringed circus of projects going on all at the same time. Projects range from repairing fuselages in the fuselage jig, building wings, fabric covering, sheet metal fabrication as well as a detailed inspection walk around to show common problem areas found on fabric covered Piper aircraft . Since many participants bring projects of their own the list of things going on is endless though it all revolves around the restoration of fabric covered Piper airplanes. Steve has a well tooled shop that specializes in the restoration of Piper aircraft with much specialized tooling that is made available to participants to learn and use. One of the scheduled projects for this year include the repair of the fuselage for the PA11 made famous in Rinker Buck's book "Flight of Passage". Chris Nesin of St. Louis, MO has the bare fuselage here for repairs including the bird cage superstructure. Mark Erikson of Dakota Cub will be on hand to demonstrate wing assembly including the proper way to trammel among many other helpful hints. Jason Gerard of Stewarts Fabric System will be in attendance teaching the art of fabric covering using their water based fabric system. Bushwheel Bill and Dianna Duncan will also be here in the Bushwheel Mobile for anyone wanting tires or tailwheels. One of the unique aspects of this event is the broad range of experience levels of the participants and the vast knowledge available. It is a hands on workshop where the attendees can get as involved as they wish and dirty hands are common. The camaraderie is second to none with Texas hospitality and lots of good food to boot. The main event happens over the weekend but many stay throughout the next week. Enrollment is $150 per person or $175 per couple for the weekend or $250 per person or $275 per couple for the week. Cathy is putting together a survey that I will post later for anyone planning on attending. Any questions feel free to contact me [email protected]

[N96337]

Re: aircraft coveering

As I undersstand it, the "fabric" for both systems is the same or at least quite similar; heat is used to activate the glue for attaching the material and a housold iron is used to shrink the material. The main diifference is the glue, paint and other products involved in the process. Am I correct? thanks for your input

Sorry I didn't notice this earlier Lee.
The Stewarts system can use any of the certified fabrics. I'm understanding that there's a difference in the sizing and other finish aspects on some of the fabric available now, whereas it used to be all from basically the same mill and roll.
The Stewarts glue isn't heat activated, but will soften and rebond with heat. It's more of a "contact" type of cement, and not as fast curing as the MEK based cements, such as Superseam or Polytak. Stewarts glue is much more flexible and stronger in shear and especially in peel, than the other approved glues. It's the only system that is approved for glued seams over no structure, that I'm aware of.
The Stewarts website has some great info on it, and the advantages. http://www.stewartsystems.aero/default.aspx

SWOERIC, that sounds like a great time at Steve's place! Lots of talent and great people there!
John

[Leenicklas]

Re: aircraft coveering

I appreciate your input. New KitPlane Mag has article on Stewart system. I think I wll order their set of CD's; Maybe will go to one of their seminars. I plan to use the Stewart system. Thanks again.

[NY86]

Re: aircraft coveering

We taught Stits for years at the local Community College. This past fall we taught Stewart's. the instructor gave it an A+ (not my class...)

[magman]

Re: aircraft coveering

Anyone remember "Irish Linen & "Razorback"?

[Hank Jarrett]

Re: aircraft coveering

Irish Linen and Grade A Cotton were WONDERFUL! SO easy to use and you could put a beautiful finish on them. Just thinking about it I can remember chewing the Dope of my finger tips. I miss the smell (just a LITTLE of it, it could make you really nauseated if you got too much). Anybody remember they used to say you should drink lots of milk to get rid of the Dope Fume problems? Never worked for me. Had to keep lots to fresh air moving in. We used to put a few drops of "Oil of Wintergreen" in the dope to cut the banana smell. Had to ne REALLY careful about humidity and ESPECIALLY open flames around the Nitrate Dope. Cotton with Nitrate would burn like mad!
As for Razorback, I HATED it! HEAVY (I mean REALLY HEAVY!) and the edges would cut you. Only advantage I saw was it was also strong as a bull. I swear you could patch torpedo holes in a battleship hull with it. Never used it on a light plane, but we did cover the tail surfaces of a DC-7 with it. ALMOST had a weight problem! If the control surfaces weighed too much or the CG of the surface was too far aft you could get flutter in the surface, so we had to weigh each one and do a hinge moment measurement before we could return them to service. Lucky for us they were painted silver so we didn't have to add color coats.
Hank
Old memories of good times. Sniff, sniff!

[N96337]

Re: aircraft coveering

Razorback was actually invented/approved by an old Taylorcraft employee. Ken Culler had worked for Taylorcraft when he was young, and he was the guy that got Razorback as well as Superseam approved. Interesting guy! He told me that he sold the rights to BOTH for $1500.... he said he really needed the money, and it was a pretty good price at the time.
A friend of mine had a Curtiss 12E that was covered in Irish linnen, and it was still testing ok as of about 15 years ago... pretty, but I'll stick to the synthetic components!
Leenicklas, you'll like the Stewarts....as long as you can follow instructions to the letter and don't try to make it work like the more "traditional" systems! I used to teach it, in the late 90's, and the ones that had problems, were people that wouldn't listen and follow the instructions carefully! Quite often, I'd wind up with a husband/wife team in the class, and 9 times out of 10, the wife would have way less problems with all of it, and would wind up with a better job, because she'd listen and do what was told. Us guys seem to think we know better.....
John

[lawheelock]

Re: aircraft coveering

I covered my Stinson 108 with Razorback in 1978 and it is still as good as new. The Razorback fabric is no heavier than any other fabric in oz per square yard. It could not be easier as a covering medium. I have felt that my plane was heavier, not because of the fabric, but because I sprayed 18 coats of dope on it. The beauty of Razorback is that you only spray the finish, never brush. People who had problems with it were people trained on cotton. If any dope drips through the weave on Razorback it won't shrink as the fabric itself does not shrink but the dope pulls it taught. People were used to cotton which you brush dope on and purposely brush it through the weave. I weighed my Stinson last week and it was only a few pounds heavier than calculated over the last 60+years. Razorback seems to have faded away because no one ever has to recover. The extra weight I see, which maybe dirt and grease, is still less than that of a metalized Stinson and is a whole lot easier to inspect and repair. Razorback is never punch tested. Only the dope is inspected for flexibility and by having lots of coats and keeping the plane inside, the dope is still very flexible after 30+ years. I will not plan to use Razorback on my T-craft or chief because the wings are less rugged for the somewhat uncontrolled shrinkage of the dope on Razorback which can result in bent trailing edges etc on the lighter structures.
It was my first covering job and could not have been easier. All seams are simply glued with dope, tapes laid in dope etc. All in accordance with the instructions with the STC and I spent a day in the Arkansas Razorback facilities where the folks were covering crop duster wings. I have flown the Stinson more than 1800 hours since covering in 1978. The dope and fabric still looks new, when cleaned up. The most time consuming part of redoing the plane was the stripping and painting of the metal parts. A Stinson has a lot of factory metal, including all the tail surfaces, cowling, doors,LG fairings and the flaps. Stripping and painting took forever compared to spraying dope on the wings and fuselage. Now, the enamel on the metal is peeling and looks bad from expansion and contraction of the metal over the years.
If I was recovering a Stinson or other heavier plane today and if it was available, I would use Razorback.
Larry Wheelock, A&P IA
BC12D N96179 (project), Stinson N584LW (flying), Mooney N79806(flying), Chief N31979.(project)

[Hank Jarrett]

Re: aircraft coveering

That sounds like a pretty good endorsement of Razorback to me. When I tried working with it I was a confirmed Grade A person and I don't remember spraying the finish on, so your point about weight from brushing could have been the cause of the weight problem. I DO remember having a problem with dope forming droplets on the inside surfaces of the fabric and it making little circles that showed on the surface where the drops were on the other side. Funny I had forgotten about that. Of course that leads me to further believe we were using brushes.
On the DC 7 I do remember they used sprayers there (it was a Navy rework facility) but a DC 7 tail is PLENTY strong. Compared to a DC 7, a crop duster is a micro film model.
Hank

[lawheelock]

Re: aircraft coveering

Hank,
When I was at the Razorback "Plant" in Arkansas in 1976 learning from the experts how to use it, they told me that at that time most of their market was to the Navy because the Navy would not allow any other fabric to be used on their DC3s/C47s, DC6s and any other Navy aircraft still in the inventory at that time that had fabric surfaces. They also showed me their trick for forming the compound curve where the vertical fin intersects with the fuselage and it came out beautiful. Most Stinsons have been recovered with a tube or rod inserted but the original factory covering did not use anything there. The instruction sheets that they supplied with the STC clearly stated that first coats shall not be brushed and that no dope should ever penetrate the weave. The only brushing allowed was to seat reinforcing tapes and finishing tapes only after the weave was sealed with several sprayed thin coats of dope. The fabric was pre-treated with a butyrate compatible treatment so adhesion of the dope was never a problem. No nitrate was used. I covered an aileron first as practice and from there on it was fast and easy. I had wing supports that allowed rotation and as fast as I sprayed a coat on one side and then the other it was ready for a cross coat on the first side. Like I said, the bad reputation came from folks that tried to do it like cotton or linen. I wish I could put it on the T-craft but fear the over shrinkage.
Larry Wheelock