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oxidation of bullion on collar tabs
Greetings.
I often see SS collar tabs with both runes and standarte numbers with some degree of oxidation. I usually purchase such items in as good as possible condition but this one has caught my eye. From Hannahs Reich, it shows a medium level oxidation. Can any members shed light on the causes of this (yes I know... water and oxygen). From my memory Aluminium metal has a stable surface oxidation layer (unlike iron). Possibly, this is due to the oxide (or hydroxy oxide) not being greater in volume than the metal and so not flaking off to expand as surface oxidation occurs. One sees various degradation such as fracture or peeling of the Al from the base material or this powdering oxidation as shown here. Can any members shed further light on their experiences. does it continue to degrade once it starts (as i have seen worse) or will correct storage conditions stop further degradation?
Thanks for any input. Also I hope you like this tab. Thanks,Paul
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10-04-2013 11:15 AM
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Hi Paul,
You've basically got all the answers already, but I can confirm to you that stored under proper conditions, further oxidation and damage will be averted. The thin layer of oxidation already present will act as a buffer against further corrosion if these conditions are maintained.
Regards, Ned.
'I do not think we can hope for any better thing now.
We shall stick it out to the end, but we are getting weaker of course, and the end cannot be far.
It seems a pity, but I do not think I can write more. R. SCOTT.
Last Entry - For God's sake look after our people.'
In memory of Capt. Robert Falcon Scott, Edward Wilson, Henry Bowers, Lawrence Oates and Edgar Evans. South Pole Expedition, 30th March 1912.
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There are also embroidery sites connected with the British Museum, I think, on line and they have very nice insights into all of this of a professional nature.
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Thank you, gentlemen, for your considerations. I will investigate further and hopefully find something of interest and help to members. There does seem to be 2 main effects: 1. The oxidation which seems to almost bind the strands together where they touch...(especially after the upper most surface is probably cleaned or rubbed to expose fresh Aluminium). 2. Fracture of the Aluminium away in short lengths from the textile fibre substrate.
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The other part, actually, is the desire for a piece devoid of age goes against reality. These things are eighty or so years old, so they are historical objects with their patina.
I have become far more tolerant of such a fact as the decades have passed.
I think moisture with the aluminum wire is the most dangerous thing.
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Last edited by Friedrich-Berthold; 10-05-2013 at 02:56 AM.
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by
backtothefront
Greetings.
I often see SS collar tabs with both runes and standarte numbers with some degree of oxidation. I usually purchase such items in as good as possible condition but this one has caught my eye. From Hannahs Reich, it shows a medium level oxidation. Can any members shed light on the causes of this (yes I know... water and oxygen). From my memory Aluminium metal has a stable surface oxidation layer (unlike iron). Possibly, this is due to the oxide (or hydroxy oxide) not being greater in volume than the metal and so not flaking off to expand as surface oxidation occurs. One sees various degradation such as fracture or peeling of the Al from the base material or this powdering oxidation as shown here. Can any members shed further light on their experiences. does it continue to degrade once it starts (as i have seen worse) or will correct storage conditions stop further degradation?
Thanks for any input. Also I hope you like this tab. Thanks,Paul
Hi Paul,
The key here is, as FB and you noted, water. However, the processes taking place have a bit more to it than just the addition of water. The reaction to form aluminum oxide from aluminum metal and water is thermodynamically favored ( delta G is quite negative, even at room temperature). What keeps this process from moving forward without disruption in the absence of an agent the inhibits the formation and adherence of the aluminum oxide layer. This layer, only a few microns thick, is what keeps aircraft from disintegrating, cookware from dissolving, and, last but not least, our Nazi regalia from turning to dust.
In the presence of a promoter that disrupts this oxide layer, be it a base (hydroxide ion), an acid (HCl) or a salt (NaCl), this protective and nearly diamond-hard surface will weaken its cohesion and adhesion to the underlying surface. These promoting agents are all found on our skin and in the oily residue that we leave behind when we touch something. At room temperature, the process takes some time, but, it does happen. Given that the aluminum wire used in the embroidery is so thin and flexible, it is very vulnerable to this chemical degradation and is only hastened by mechanical forces that bend the wire and further expose reactive metal.
The less we handle these things, the longer they will be around...but unless they are stored in an environment completely free of these substances, perhaps in a sealed container under a nitrogen gas environment (but where is the fun in that), all insignia will eventually turn to this powdery dust. There's no getting around the laws of thermodynamics.
Regards,
CMH
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Your post mirrors my great fear. I keep my things dry; out of the sun light; away from the moths; away from human fingers; and any rubbing and such, and hope for the best. I cover them, too, which likely is bad, but such also militates against all the other threats.
will, one day, become this...
What I have been able to learn out of all this is that it is a waste of time me having my body cryogenically frozen as by the time I "come back" all my militaria will be a little pile of dust!! 
Leon.
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