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#1
January 28th 04, 01:32 AM
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In article ,
Ed Wischmeyer wrote: Folks, the question is not about alternatives to alodyne, or about primers -- it is how to alodyne large sheets without having huge quantities of chemical!! Unfortunately, IMHO, there is no alternative. As you know, Ed, I had an alodyne tank setup in CA, which I made up, using a lye solution for etch and a companion tank for the alodyne. I got the lye from the supermarket and the alodyne powder from a plater. For best reaults, the lye should be at 120 dg f. Etch for 5 minutes, wash, alodyne for 10 min., wash. 
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#2
February 1st 04, 08:17 PM
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On Wed, 28 Jan 2004 01:32:55 GMT, Orval Fairbairn
wrote: In article , Ed Wischmeyer wrote: Folks, the question is not about alternatives to alodyne, or about primers -- it is how to alodyne large sheets without having huge quantities of chemical!! Unfortunately, IMHO, there is no alternative. As you know, Ed, I had an alodyne tank setup in CA, which I made up, using a lye solution for etch and a companion tank for the alodyne. I got the lye from the supermarket and the alodyne powder from a plater. For best reaults, the lye should be at 120 dg f. Etch for 5 minutes, wash, alodyne for 10 min., wash. Using lye ( sodium hydroxide ) for an etch is a disasterous choice. The treatment you describe will more than remove all of the alclad from the sheet and leave you worse off than when you started. O-ring
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#3
February 1st 04, 08:31 PM
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#4
February 3rd 04, 04:00 PM
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I'm reminded of the time a student in an automotive class put his engine block in the caustic solution over the weekend. It works great on a cast iron block. Removes all the crud, paint, etc. However, on Monday, when he opened the tank to remove his block, all he found was a few bits and pieces plus the cylinder liners. Caustic solutions and aluminum are NOT a good mix. Even an aluminum engine block can be "eaten away". Think what it will do to a thin aluminum skin... John I think the worst thing many of us has seen is someone buffing away the alodyne on an older airplane to shine it up. Once the alodyne is gone, the shine doesn't last and the skin re-oxidizes deeper. It corrodes the airplane away in short order. BWB
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#5
February 2nd 04, 01:12 AM
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Using lye ( sodium hydroxide ) for an etch is a disasterous choice. --------------------------------------------- Not necessarily. Not all aluminum is Alclad and sodium hydroxide has long been a standard for surface preparation for aluminum. But as with heat treatment or re-forming, it isn't an amateur sport :-) -R.S.Hoover
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#6
February 2nd 04, 10:42 PM
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#7
February 3rd 04, 02:37 AM
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The aluminum metal definitely goes away. I
stand by my statement, and Alclad was not the point. Bob Seals M.S. Chemistry ----------------------------------------------------- Dear Bob, Of COURSE the aluminum goes away... if you use a strong enough solution or leave it in the tank too long. But since you DID mention Alclad I think it's fair for me to have assumed that WAS your point especially since lye has been used as a surface treatment since Jeeter was pup. (Indeed, it is a REQUIRED step for some finishes.) -Bob Hoover (no, I'm the other one) -Greasy Fingernails (and fifty years experience) PS - you would have had better luck with your ballons if you'd used iron filings and sulphuric acid... and yes, acid was -- and still is -- a standard method of surface treatment for some metals. Visit a plating shop. Or an aircraft factory :-)
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#8
February 3rd 04, 03:57 PM
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