Originally Posted by fernando
There certainly must be a metallurgic explanation for the apparent lack of patina. In any case it is visible that it has not been tampered with; and so far i am confident will over that.
Thanks for explaining it. Question: In "real life" does the metal on the exposed part of your tang have a somewhat bluish tinge?
If so it might be mill scale, a tough oxidized "skin" that forms on iron when hammered or worked at forging heat. The stuff is surprisingly durable, it clings tenaciously to the underlying iron and retards corrosion. I've noticed, when experimenting with a file on pieces of old junk iron which has the layer intact, that this thin layer tends to be harder than the underlying metal. So it is quite abrasion resistant. I have removed loose handles from damaged swords which I know to be 18th cent. or even earlier, and been surprised to see patches of this bluish skin intact in places not attacked by the rust which you would expect from something that old. Often, the undisturbed scale and the rust pitting are right next to each other. I am sure that if the tang was ground or polished so that all the scale was removed at time of manufacture, the entire tang would have rusted more consistently.