Born Alexander Thompson MacKaye in Scotland. Apprenticed to a bookbinding tools manufacturer. Went to London in 1850 and worked for punch-cutting expert John Skirving, where he cut typefaces for prominent English typefounders, such as Henry Caslon, Vincent Figgins, and the Stephenson Blake company. Took the offer of a full time position at the L. Johnson & Co. in Philadelphia in 1854, where he changed his surname from MacKaye to Kay. He stayed with L. Johnson & Co (later Binny & Ronaldson, then MacKellar, Smith & Jordan) for 40 years, until he lost much of his sight to cataract. He also spent several years engraving dies for minting coins at the Philadelphia mint.