I bought a rather large, somewhat rusted, antique garden urn made of cast iron for my wife. It dates to about 1920 and, to my knowldege, has been outdoors the entire time. Initially I wanted to wire brush it, sand,prime and paint with Rustoleum but am having second thoughts.
My question is: Since it is an antique and made of cast iron, will I damage it by wire brushing, sanding, priming and painting or should I leave it as is, rusted and in need of a paint job, to rust away in the garden? Also, the urn's value be reduced if it is painted?