Question: I have some old metal tintype photos. Can you tell me when they first started using this form of photography in the United States? Answer: The mention of such a photo process was discussed by Adolphe-Alexandre Martin in France in the year 1853. A gentleman by the name of Hamilton Smith patented the idea in the U.S. in 1856. Most tintypes I have examined however are generally from the 1860's to the early 1900's. This is the original patent for the idea in the U.S. in 1856 -
http://www.google.com/patents/US14300?pg=PA1&dq=hamilton+smith+photography&hl=en&sa=X&ei=wTqbULG4CK-n0AGui4DgAw&sqi=2&pjf=1&ved=0CDQQ6AEwAA#v=onepage&q=hamilton%20smith%20photography&f=false