I was wondering if anybody had formulated a systematic method of approximating the date of manufacture of razors.

Across the 19th century, the grind, curve and width of the blade and the shape of the monkey tail changed over time. As records of production are very sketchy at best, I was hoping that some of the more scholarly members here had posted or would do a wiki on how the design of razors changed over time to make dating old razors easier.

Thanks!