Yup, makes sense though.
There's so much we don't know (or have lost). Fermented persimmon juice is a waterproofing agent for paper - coat it on any ferrous metal though and it produces a hard black surface that'll prevent it rusting (I know, I've done it).
Then there's the Iron pillar of Delhi that might be as much as one and a half thousand years old. The pillar, "...is 98% pure wrought iron, and is a testament to the high level of skill achieved by ancient Indian blacksmiths. It has attracted the attention of both archaeologists and metallurgists, as it has withstood corrosion for over 1,600 years in the open air." http://en.wikipedia.org/wiki/Iron_pillar_of_Delhi
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