I met someone working on restoring a Pasadena bungalow built in 1911. She brought a hinge to show me, in hopes that I'd have a clue about how to remove the grunge without damaging the original look. Unfortunately, I don't know much about how to clean up old hardware, but I am quite good with the Googles.

The hinge was manufactured by The Stanley Works. The "Sweetheart" stamp was created to honor the president of the company from 1884 to 1915, William Hart. I took a screenshot from "The Handplane Book" that describes the trademark usage. I love history. :)