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T-6 Corrosion Resistance

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naumuk(at)alltel.net
Guest

Posted: Wed Nov 05, 2008 3:35 pm Post subject: T-6 Corrosion Resistance

Z-Builders-

     For all of you touting the  corrosion resistant qualities of T-6, look at the attached picture. This is the  only original skin I still have- I keep it around to make L angle out of. The  T-6 picture was taken in the garanger, "Other stuff" was taken in the basement.  Not exactly severe conditions. 

     My skins were stored standing  upright against the panelled walls of my basement (Where a dehumidifier was  running 24/7) in their paper wrapping. When was ready to install them, this is  what I found when I unwrapped them. Consequently, I literally had to rebuild 75%  of my factory supplied parts from scratch. And yes, the factory T-6 marks are on  all the bad skins.

 Bill Naumuk

Townville, Pa.

HDS 601MG/Corvair  95%

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Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Wed Nov 05, 2008 4:14 pm Post subject: Re: T-6 Corrosion Resistance

I had a piece that got damp in the wrapping paper. Top rear fuselage skin that looked much like that. There was no pitting and it cleaned up just fine with some stuff I found at Home Depot.

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

bryanmmartin

Joined: 10 Jan 2006
Posts: 1018

Posted: Wed Nov 05, 2008 4:33 pm Post subject: T-6 Corrosion Resistance

6061 is corrosion resistant, much more so than 2024, but it is not corrosion proof. The paper it came wrapped in is to protect it during shipment. In a damp environment, the paper can hold moisture which can not only promote corrosion directly, it can promote biological growth which can be another source of corrosion. Even with de-humidifiers, basements tend to be damp and if air can't circulate around the metal to purge the moisture, you can end up with a favorable environment for corrosion.

On Nov 5, 2008, at 6:34 PM, Bill Naumuk wrote:

 	  Quote: 	
		  Z-Builders-

    For all of you touting the corrosion resistant qualities of T-6, look at the attached picture. This is the only original skin I still have- I keep it around to make L angle out of. The T-6 picture was taken in the garanger, "Other stuff" was taken in the basement. Not exactly severe conditions.

    My skins were stored standing upright against the panelled walls of my basement (Where a dehumidifier was running 24/7) in their paper wrapping. When was ready to install them, this is what I found when I unwrapped them. Consequently, I literally had to rebuild 75% of my factory supplied parts from scratch. And yes, the factory T-6 marks are on all the bad skins.



	




 -- 

Bryan Martin

N61BM, CH 601 XL,

RAM Subaru, Stratus redrive.

do not archive.



 



 [quote][b]

_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive.

grs-pms(at)comcast.net
Guest

Posted: Wed Nov 05, 2008 5:21 pm Post subject: T-6 Corrosion Resistance

Someone more knowlegeable may correct me on this, but I  believe the manufacturing process for kraft paper and for corrugated cardboard  results in a finished product which is somewhat acidic. I know that regular  cardboard shouldn't be used to back framed pictures or documents for that  reason.  It probably shouldn't be in long-term contact with any sort  of aluminum, even in conditions of low humidity.

  

 Incidentally, T-6 refers to the heat-treatment rather than the  alloy itself.  The alloy is 6061, so the full designation is 6061-T6.   It does give good service in aluminum canoes and boats, so it must be at  least somewhat corrosion resistant.

  

 George

 ---

dbrown(at)avecc.com
Guest

Posted: Thu Nov 06, 2008 7:10 am Post subject: T-6 Corrosion Resistance

This is interesting, my top rear fuselage skin looked like that also.

Now I am thinking that it came from Zenith like that.  I cleaned with

MEK, then precote and Scotchbrite and it came out fine.

Just finished the 40 hrs, took my first passenger Sunday, (my wife).



David

N601EX

Aviation in itself is not inherently dangerous. But to an even greater

degree than the sea, it is terribly unforgiving of any carelessness,

incapacity or neglect.






I had a piece that got damp in the wrapping paper. Top rear fuselage

skin that looked much like that. There was no pitting and it cleaned up

just fine with some stuff I found at Home Depot.



--------

W.R. &quot;Gig&quot; Giacona

601XL Under Construction

See my progress at www.peoamerica.net/N601WR





Read this topic online here:



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Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Thu Nov 06, 2008 7:50 am Post subject: Re: T-6 Corrosion Resistance

Just a coincidence. I know how mine got wet (a very small leak during a very heavy rain) and the only way Zenith is to blame is that they packed that particular piece at the bottom of the stack.



 	  dbrown(at)avecc.com wrote: 	
		  This is interesting, my top rear fuselage skin looked like that also.

Now I am thinking that it came from Zenith like that.  I cleaned with

MEK, then precote and Scotchbrite and it came out fine.

Just finished the 40 hrs, took my first passenger Sunday, (my wife).



David

N601EX

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

naumuk(at)alltel.net
Guest

Posted: Thu Nov 06, 2008 3:24 pm Post subject: T-6 Corrosion Resistance

Dave-

    MEK, eh? I tried everything under the sun but that, including to try to 

polish it out with Nuvite with no luck.

                                                                Bill

---

ideaz1(at)sbcglobal.net
Guest

Posted: Thu Nov 06, 2008 6:33 pm Post subject: T-6 Corrosion Resistance

Aluminum oxide will disolve almost instantly with Lye. It will also remove 

anodizing which is a form of aluminum oxide.

---

dbrown(at)avecc.com
Guest

Posted: Fri Nov 07, 2008 6:27 am Post subject: T-6 Corrosion Resistance

Bill,

The MEK was used only to remove the grease from fingerprints and

handling.  The Prekote and Scotchbrite were what I felt did the trick.

The fuselage was painted about 2 years ago and the wings about 1 year

ago.

I used 2 part NAPA automotive paint.  Still looks great.

David



"If you are looking for perfect safety, you will do well to sit on a

fence and watch the birds; but if you really wish to learn, you must

mount a machine and become acquainted with its tricks by actual trial."



- Wilbur Wright

--

naumuk(at)alltel.net
Guest

Posted: Fri Nov 07, 2008 3:52 pm Post subject: T-6 Corrosion Resistance

In other words, you weren't able to remove the corrosion, just prep for 

painting.

                                                    Bill

---

naumuk(at)alltel.net
Guest

Posted: Fri Nov 07, 2008 4:04 pm Post subject: T-6 Corrosion Resistance

Dirk-

    Too late for me now, but I think this belongs in the archives if it 

works.

                                                                             

    Bill

---

ideaz1(at)sbcglobal.net
Guest

Posted: Fri Nov 07, 2008 4:41 pm Post subject: T-6 Corrosion Resistance

I was doing my own anodizing a couple years back (it's a pretty simple 

process) and if you mess up you just dunked the part in a lye solution to 

clean it off then started over. There's a drain cleaner called Red Devil and 

is mostly lye, that you can probably still get at the grocery store. I'll 

look up the actual chemical name and post it later (gotta find the book).



A couple interesting things about aluminum oxide (anodizing is an oxide 

chrystal layer that looks like a microscopic honey comb which can be filled 

with dye for color and when heated the cells close up sealing in the dye)for 

those who don't know:1 it is very hard (aluminum oxide sandpaper will cut 

steel) and corosion proof.2 it is non conductive.

Dirk

---

planes_by_ken(at)bellsout
Guest

Posted: Sat Nov 08, 2008 5:47 pm Post subject: T-6 Corrosion Resistance

Take a look at the metal with a magnifying glass and a bright 

flashlight.  If there are no pits then it probably is just staining, not 

corrosion.  Aluminum corrosion products are generally a white powder 

that is not too hard to remove.  Try cleaning with some Alumiprep 33.  

This is what is used to prep for applying Alodine, painting or welding.  

The Alumiprep should foam up and bleach the surface to almost white.  

Flush with plenty of cold water.  Remember to dilute with water as 

directed.  You don't need to use Alodine afterwards unless you want to.  

A natural layer of aluminum oxide will form quickly and seal the surface 

back up.  Not to open old threads but....  3M maroon scotchbrite is 

aluminum oxide based and is OK on aluminum.  Don't use silicon carbide 

sandpaper on AL.  It can lead to corrosion (per AC43.13 2A)  3M offers 

an aluminum oxide wet or dry paper (Imperial) that is no more expensive, 

just had to find.    I you want to see some impressive corrosion I could 

post a image of a Cessna wing mounting block with intergranular 

corrosion.  Flat out 6061 is much more corrosion resistant than 2024.  

It is all  we can do to prevent 2024 from corroding.  Most single engine 

Cessnas prior to the 90's were not zinc chromated unless equipped to 

have floats.  We have it easy.

Ken Lilja

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