Comment by fnordprefect
3 years ago
In (I think) the first edition of Zumdahl's chemistry textbook, there was a great summary of some of the things they had to do to preserve the statue, and it went beyond just repairing the skin.
The wiki article (https://en.wikipedia.org/wiki/Conservation-restoration_of_th...) has a lot of it, but IIRC after they installed stainless steel, at some point they passed electricity through it, which had the effect of making it susceptible to corrosion, and then had to do something else to restore its resistance.
I wish I could find it now, as it was a fascinating read, but I can't see anything easily online.
One of the NYT articles at the link mentions the stainless steel.
This WaPo article talks about it more: https://www.washingtonpost.com/archive/politics/1986/07/02/b...
This article suggests that the DC current treatment was to avoid corrosion (also has some nice illustrations of the support framework for the skin):
https://copper.org/education/liberty/liberty_reclothed2.php
A related blurb just says they built some equipment (probably the equipment to do the DC annealing, but who knows):
https://www.romanmfg.com/roman-manuacturing-helps-restore-th...
The Wikipedia article mentions the annealing and then sand blasting to remove iron from the surface (contaminants on the surface of the stainless can compromise the oxide layer that forms).
Maybe something in there will jog your memory.
stainless passivation usually involves an acid to form an oxide layer. wiki says nitric and citric, but we used to use an HF gel which was pretty damn nasty
edit: I rabbit holed a little bit. apparently its not that straightforward. the acid encourages the iron to leave the surface layer (probably through oxidization and dissolution) with just the chromium and the nickel. this then oxides in the presence of air, leaving a protective layer without the surface iron to start to rust
That's fantastic, thank you!