I just picked up a bunch of old regimental day sporrans. They're pretty old, judging from the fusty smell and still have their previous owner's names and serial numbers on the inside etc. I have a project in mind for them but something that struck me was that they are made from lovely brown grained leather so why are they polished black?

I know this is regimental orders but what would be the reason for doing this? If dress orders state black sporran, why wouldn't they be ordered in black leather from the supplier? Variously some of the accompanying straps are brown, some black polished some, black patent. I don't understand the variation I'm seeing in the same dress item.

Secondly, and more importantly, what is the easiest way to remove this polish without harming the brown grain underneath?