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Aluminum oxidation with Sinar metal frame

robert seto , Dec 08, 2006; 12:12 p.m.

Greeting to all,

I have recently traded my trusty Deardorff 810 for a Sinar 810P, trust me, there is madness behind my thinking. Anyway, on the Sinar ground glass holder, there are many white spots, almost like fungus and feels powdery/chalky when I touched it. I am guessing it's metal oxidation and if so, what is the cure for it and how to prevent it from further degradation.

I really should have taken a picture of it before I clean them off, but it did look a lot worst and it's wide spread through out the interior frame and inside the crests.

Thanks for any helpful responses in advance

Attachment: detail_sm.jpg


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Michael Axel , Dec 08, 2006; 01:10 p.m.

I lived on the Oregon Coast for some time and had this problem with my enlarging equipment. I'm quite sure mine was from salt water oxidation. My cameras were always in Halliburton cases and never suffered the same problem, thank goodness.

Felix Ackermann , Dec 08, 2006; 01:33 p.m.

I have the same problem on the frames of the 5x7 inch bellows (normal and bag) of my Sinar Norma. It didn't matter so far, because I only used the 4x5 and 8x10 inch equipment.

But this could change - so I would be eager too to know how to clean and treat these frames properly.

robert seto , Dec 08, 2006; 01:35 p.m.

Hi Michael, you are indeed fortunate then. My curiosity about my camera's situation is how they might have formed. I am thinking because it's happening from underneath the paint so that means the paint is not offering any protection to the metal. Second, the camera is in the middle of the continent so salty air is not an issue and neither was it out in snow and slush so where is the contaminants coming from. The second concern is how I can prevent it from further developing???? I can't keep it in some vacuumed space for ever right:)

robert seto , Dec 08, 2006; 01:44 p.m.

Hi Felix,

I don't think it will be an immediate threat the functionality of the camera nor does the cosmetic condition bothers me, but if this is anything like the bicycle fork which I was using in the snow and slush, and it promptly crumpled away like dry turds in a matter of two winters, I would like to know how I can stop if not at least delay the process.

Jeff Bishop , Dec 08, 2006; 03:35 p.m.

If I had this problem, and it bugged me enough to deal with it, here's what I would do:

Sand the entire aluminum part (or all aluminum parts) lightly to remove paint. Once I was down to the aluminum, I would "etch" it with what they (do or did) call 'Metal Prep.' Afterwards I would follow with a good black aluminum paint.

The alternative, though I'm not sure of the price (could be very high) would be to have the parts powder coated.

I'm no expert on the matter (disclaimer). Hope something here helps!

robert seto , Dec 08, 2006; 04:42 p.m.

Thanks for the suggestion Jeff, and oh yes it's bugging me a lot. I was praying that it does not come down to having it completely sanded, re treated and painted. That would be a job and a half given that in fact it's not flat and one piece like a lens board. But if it's the only way of being sure, winter is here...sigh.

John Schneider , Dec 08, 2006; 04:52 p.m.

The best way (i.e., the way it's done in aviation and aerospace) to deal with local aluminum oxidation is to mechanically remove (sanding, etc.) all the corrosion you can. Clean the corroded area with Alumiprep per the instructions (using gloves of course), treat the now-clean area with Alodine to chemically convert it to a good paint base, prime with a zinc chromate or zinc oxide primer, followed by the top coat of your choice. Nothing else works even half as well. A good auto paint store should have Alumiprep and Alodine, or you can order them from a homebuilder's supply like Aircraft Spruce. This process is a bit of a pain, so you'll have to decide if the benefits are worth it to you.

Frank Schifano , Dec 08, 2006; 07:43 p.m.

Having observed a good bit of old aircraft preservation at a local aviation museum, I can second that suggestion.

robert seto , Dec 08, 2006; 07:59 p.m.

Thanks John and Frank,

Should I do the entire frame or the areas being affected, the reason I am asking is that as I was cleaning off the chalk like powder off the spots, I notice there seems to be a layer brownish substance, approaching the color and texture of the powdery stuff on the surface just under the black paint, so I am wondering if the whole frame is under siege..

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