Dope and STCs

[bob turner]

Just ordered some dope - up to almost eighty bucks a gallon. Sales guy said that you no longer can mix dope. If you start with Certified, all coats must be Certified. Same with Randolph. I think it is a paperwork problem, rather than an adhesion issue. Thankfully, dope doesn't have those PMA stamps every foot along the edges.

[citabrickr]

I think it is a paperwork problem, rather than an adhesion issue.

Willing to risk doing the whole job over again if you're wrong? That's the real question.

[bob turner]

Yeah? The Citabria requires dacron and dope, by type certificate. All the materials need to be is PMAed. If it works on Decathlons, you can be sure it will work on Cubs.

[aalexander]

Yeah? The Citabria requires dacron and dope, by type certificate. All the materials need to be is PMAed. If it works on Decathlons, you can be sure it will work on Cubs.

Well of course Dacron and dope works, why wouldn't it?

Maybe you could clarify exacly what you are asking:

Mixing two different brands of Butyrate dope together and applying?

Mixing coats of two different brands of butaryate dope?

Mixing coats Butyrate dope and PolyBrush?

[bob turner]

I wasn't asking. My comment is that now the major dope supplier has figured out that if you start with his product, you must finish with his product. I found that out by buying a gallon of Randolph Butyrate, and a gallon of Certified Butyrate thinner. Sales person says they are the same, but it is now against the FAA regs to use any kind of mixture. That is, if you start out with Randolph nitrate, you cannot go to any other brand for clear, silver, or topcoat. Unless you own a Citabria or Decathlon.

[aalexander]

I wasn't asking. My comment is that now the major dope supplier has figured out that if you start with his product, you must finish with his product. I found that out by buying a gallon of Randolph Butyrate, and a gallon of Certified Butyrate thinner. Sales person says they are the same, but it is now against the FAA regs to use any kind of mixture. That is, if you start out with Randolph nitrate, you cannot go to any other brand for clear, silver, or topcoat. Unless you own a Citabria or Decathlon.


Ahhh, ok. Did he quote the regulation, or AC, or anything which supports that?

[bob turner]

It wouldn't be a regulation. It is the STC, which has been seriously modified over the last ten years. Started with Stits, which allowed top coat with anything, until somebody used a boat paint that peeled the Stits coatings off in flight. Then Stits bought Ceconite - and now Super Seam and Poly Tak are out of the same barrel, but don't try mixing them. For what I would call conventional Dacron covering systems, all that is left is Super Flite, and maybe they have also restricted coatings to their own brand. It is time to release this stuff, just like patents. Let STCs become simple 337s after a quarter-century. Opinion.

[Steve Pierce]

A friend recovered his Bücker Jungmeister with Randolph dope. Less than 30 hours and while sitting in the hanger the whole finish cracked like an egg shell. We speculate they got something wrong at the factory. They gave him more dope but it is a mess to sand and the cracking still shows if you look just right.

[bob turner]

Uh-oh. I just got a can of yellow for eighty three bucks, and the chip on top of the can indicates that they no longer use the expensive, bright pigment. I'll post more when I spray it, but bear in mind that the Poly Fiber folks now own Randolph, and may have made some changes. I wonder if they will buy Super Flite next?

Next airplane will definitely be experimental. Better strobes, way better seatbelts, and cheaper everything, right off the same mill/ assembly line.

[Steve Pierce]

Beware Bob, they reformulated all the colors and the ones I have shot don't match. They said that Randolph ground their own colors and made it impossible to match with their tinting process. I really think given enough time it could be done if they really wanted to.

[polarpete]

Anybody out there using Air Tech Coatings process in cold climate?
How was it to work with during the covering process?
What do you think about it, any problems?

[JP]

We shot Air-Tech in a wide variety of temperatures, from about 45 degrees on up and had no problem. We thought the process was simple and produced very good results the first time. There is a lengthy post on Air Tech, so you may want to run a search (air tech, air tec, etc.).

[polarpete]

Thanks JP, I had already tried a search but I didn't have the dash or capitals in/ between the Air and Tech. Tried it again and it worked. Thanks Pete

[bob turner]

I just sprayed some Randolph Juneau White. Against the older stuff, it looks beige! I need a quart of the original Juneau White to make the airplane look a whole lot better.

I had heard they couldn't match the Aerothane Piper Cub Yellow, and there was great grief associated with re-doing one wing. All of this is disheartening. If I find a source for matching, I'll post it.