J

jeffkalo

I'm New Here
:eek: I'm a HS aerospace teacher who has inherited an RV-9A building project (begun summer 04). The tail/rudder, wings and some fuselage have been riveted. We're now working on the elevators. None has been primed inside or out. Is it worth priming the rest and trying to clean off the sharpie markered names on the built parts and prime those?
 
jeffkalo said:
:eek: I'm a HS aerospace teacher who has inherited an RV-9A building project (begun summer 04). The tail/rudder, wings and some fuselage have been riveted. We're now working on the elevators. None has been primed inside or out. Is it worth priming the rest and trying to clean off the sharpie markered names on the built parts and prime those?
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Don't even bother on what's already been built. By far the most likely place for corrosion is at the joints between parts. You'll never get any primer in there now. In 15 or 20 years if you start seeing corrosion, fog it with anti-corrosion stuff :) Just make sure that he got the biggies...there are a couple of spar caps and doublers in there that aren't alcad and need to be primed. If he didn't prime those, you're probably doing to need to seal that somehow. Vans or your tech counseler can probably help there.

re: sharpie marks....they'll come right off with MEK.

I'll just tell you what I've been doing lately. I clean the parts with some MEK, and then I shoot them with self-etching Zinc Chromate from a rattle can (Tempo 5605/5606). The stuff is not as tough as the AKZO epoxy primer I was using, but it takes me 5 minutes to prime parts rather than the 2 or 3 hours it took me with the AKZO. Others are having good luck with GBP-988 (sherwin williams rattle can). Lots of people are still doing the whole alodine and then primer over it thing. I know of one guy that's alodining, priming, and then topcoating with a sealer....on the inside, yes. So you see, there's no way to answer your question except to say find your own comfort zone, and go with it.
 
Priming question

Hello

If you only knew what kind a firestorm you could start with this question. :eek: It is probably one of the most hotly debated topics.

Anyway, if you look at the original Cessna's ect., they did not prime and many are still flying today.

For the parts that are already done, the only thing you could do is spray the insides with Boeshield T?9. Priming is not really an option because, since it was not primed already then most likely the oily film from manuafacture is still on the parts. There are other products, but you would not want to use them until after you have painted, because they will leach out of every rivet and prevent the paint from sticking.

Like the previous post, Alclad does not really require priming unless it is scratched or otherwise compromised. Priming the rest is strictly an exercise in your building philosophy. Priming is probably a requirement for resale value and if you are located in a high moisture environment. Van's factory recommendation is to prime in harsh environments. Me personally, I have used 3-4 diferent primers and Alodine, depending on what is cheapest or most easiest to work with at the time. I did not prime the large Alclad skins except where the rivet lines were. As a class project, being worked on everyday, priming is less of a hassel and probably good instruction.

Hope that helps.
 
almost forgot

If I did not make it clear, non-Alclad, definitely steel, other alloys should be primed.

And it is a good idea to remove the sharpie marks. Most inks, not 100% sure with Sharpie, contain salts which would promote corrosion. If you made your marks with wax pencils, not needed. I have used alcohol, acetone, and metal prep (this is used in conjuction with Alodine) with equally good results for their removal.
 
RV8RIVETER said:
If I did not make it clear, non-Alclad, definitely steel, other alloys should be primed.

And it is a good idea to remove the sharpie marks. Most inks, not 100% sure with Sharpie, contain salts which would promote corrosion. If you made your marks with wax pencils, not needed. I have used alcohol, acetone, and metal prep (this is used in conjuction with Alodine) with equally good results for their removal.
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Actually, sharpies are OK but that's the only kind you should use unless you know the composition is safe (pilot, I think, has appropriate felt markers as well). And there seems to be a general consensus that blue sharpies show up better under the primer than other colors and no one seems to know why.
 
I'm located In Tampa bay and I'd STRONGLY recommend priming. I've seen parts of my kit that have been sitting start to get a "haze" pretty quick here. If your worried about the completed parts just shoot them with ACF-50 or Boeshield. You live in a high humidity climate with salt in the air. Corrosion is a problem for airplanes here. The sharpie marks are not a big deal. They'll just bleed thru the primer a bit. Laqure thinner takes them off, and I usually use it as a prep before priming. I'm using the P60G2 stuff from Sherwin Williams. If you need any "local" help just let me know.
 
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