To become a printer, from the origins of the trade up through fairly modern times, you had to go through an apprenticeship. As late as the turn of the 20th century, boys (rarely girls) might start as early as age 12 or 13 down this path, after which child-labor laws and other reforms gradually pushed that up to the teens—still mostly for men. (Opportunities for women didn’t arise in typesetting and printing until the 1960s, really.)

Kids might start even younger as printer’s devils, not apprentices. In this capacity, a child of even 8 or 10 might sweep up floors, collect lead for melting, and perform other menial tasks for a little money or food. A comic strip begun in 1918, Mickey, the Printer’s Devil, seems to have such a kid featured amusingly daily with the antics of a laboring minor.

The work was hard and tedious, particularly in the days in which all material was set by hand, and people bet and drank and played pranks. When Linotypes and then Monotypes absorbed a good hunk of typesetting work in the 1870s through early 1900s, that portion of the printing plant became more office like and professional, and you can find a lot of essays and memoirs from decades after that bemoan that change.