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  #11  
Old 09-07-2018, 04:00 PM
rv7charlie rv7charlie is offline
 
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Be aware that anodizing reduces aluminum's fatigue life by a huge amount. Van's allowed for that with the wing spars, but you're rolling the dice with anything else structural.
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  #12  
Old 09-07-2018, 04:00 PM
BillL BillL is offline
 
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Good to hear others have successfully evaporated the water from old alodine. I have several containers slowly doing that now.

On the prep - I tried the easiest on several samples. Even the alumiprep will not remove oils, I used isopropyl or denatured if handy, lastly acetone (due to smell) to degrease, then dipped in alum prep for 3 min then alodine for 4-7 min depending on the age and resulting color. Rinsed with distilled water after each dip.

Like Wirejock, I tried the hand mechanical method and it produced just as nice a finish and color/time as the alumiprep. I chose ap just due to the faster speed of processing.
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  #13  
Old 09-07-2018, 04:22 PM
Aluminum Aluminum is offline
 
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Quote:
Originally Posted by BillL View Post
Like Wirejock, I tried the hand mechanical method and it produced just as nice a finish and color/time as the alumiprep. I chose ap just due to the faster speed of processing.
Or you could slap one of these onto your buffer/polisher, spray the surface with simple green (has phosphoric acid) and let 'er rip. Much faster than alumiprep or elbow grease.
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  #14  
Old 09-08-2018, 06:40 AM
Stockmanreef Stockmanreef is offline
 
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Does anodizing really weaken a part that is 1/4" thick?
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  #15  
Old 09-08-2018, 12:27 PM
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fl-mike fl-mike is offline
 
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Yes. See the award winning Safari helicopter accident report for a real-world example. The issue is a reduction in fatigue life due to micro crack initiation at the hardened surface...I think.
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  #16  
Old 09-08-2018, 06:59 PM
Stockmanreef Stockmanreef is offline
 
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then how are the spars OK? Just curious.
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  #17  
Old 09-08-2018, 07:02 PM
rv7charlie rv7charlie is offline
 
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Quote:
Originally Posted by Stockmanreef View Post
then how are the spars OK? Just curious.
see post #11
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  #18  
Old 09-08-2018, 08:22 PM
Stockmanreef Stockmanreef is offline
 
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yep--post #11 was very informative. I emailed Van's to ask the question if I can anodized the parts.
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  #19  
Old 09-08-2018, 09:15 PM
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Nedimbek Nedimbek is offline
 
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I am reading two seperate discussions going in one tread.

1. Alodine
2. Embrittlement caused by Anodizing.

The OP was only referring only to surface prep for ALODiNE and nothing for ANODIZING.

Let's point out this conflict and not make readers confused. Alodine is a very good corrosion protection without any structural side effects.

New builders or future builders who doesn't know the difference may easily be misinformed.
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  #20  
Old 09-08-2018, 10:10 PM
rv7charlie rv7charlie is offline
 
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See post #10; the op raised the idea as an alternative to alodine.

Ken,

I'm far from qualified to give you a technical explanation, so I didn't try. But I am aware of the risk, so just wanted to make you aware. IIRC, there was an article published by Van's years ago that gave a layman's description. Apparently an engineer can estimate the number of cycles to fatigue failure in un-anodized aluminum (all aluminum has a fatigue life), and also estimate the reduction in cycles due to anodizing. Again, IIRC, the article said that the estimated cycles to failure of the anodized spar was high enough that there was little chance of reaching that number in a typical RV's lifetime. My point was that we don't know the fatigue life of other structural components if they get anodized.

Hopefully, a qualified structures guy will jump in with a better explanation.
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