From Ancestry.com Wiki
Tintype: a cheaper way to print photographs, by developing them on a sheet of tin or iron -gives the photo a cheaper, lower-quality look to it also called ferrotype or stannotype
"Not on Your Tintype" an expression used in the early 1900's meaning; No way! ; Not a chance!
In Music Man, a musical set in 1912, the expression is used It is a line of Charlie Cowell- a traveling salesman who sells anvils Used when he is stating-to Marian Paroo- that he doesn't trust her, and would rather go tell someone else to spread the word and miss his train, than leave word with her
Tintypes are frequently reverse images. If you're trying to ID a tintype that you know is a family member, try taking it into Photoshop, reversing it, and lining it up with possible target ancestor photos to see if you find a match.