From Thomas Jefferson Encyclopedia
In 1794 Jefferson added a nailmaking operation to his blacksmith shop on Mulberry Row at Monticello. He hoped it would provide a source of cash income while he restored the depleted soil of his farms. Nail rod was shipped from Philadelphia and hammered into nails ranging in size from six-pennies to twenty-pennies. In 1796 Jefferson acquired a nail cutting machine, which made four-penny brads from hoop iron.
In his Farm Book Jefferson wrote: "Children till 10. years old to serve as nurses. From 10. to 16. the boys make nails, the girls spin. At 16. go into the ground or learn trades." Up to fourteen young male slaves, aged ten to twenty-one, worked at the forges of the nailery. From 1794 to 1796, when he was retired to Monticello, Jefferson calculated the efficiency of the nailers, each day weighing their nail rod and the nails they produced. Most of the slaves who began their working lives in the nailery became tradesmen. Moses Hern and Joe Fossett became blacksmiths; Lewis and Shepherd were carpenters; Barnaby Gillette was a cooper; James Hubbard a charcoal burner; Wormley Hughes a gardener; and Burwell Colbert was Monticello butler as well as a painter and glazier.
The nailery was quite profitable in its early years, supplying nails throughout Albemarle and Augusta counties. Management problems and the competition of cheaper imported nails later made it an only intermittent source of income.
Primary Source References
1795 April 29. (Jefferson to Jean Nicolas Demeunier.) "I now employ a dozen little boys from 10. to 16. years of age, overlooking all the details of their business myself and drawing from it a profit on which I can get along till I can put my farms into a course of yielding profit. My new trade of nail-making is to me in this country what an additional title of nobility or the ensigns of a new order are in Europe." 
1795 July 10. (Jefferson to James Lyle). "A nailery which I have established with my own negro boys now provides completely for the maintenance of my family, as we make from 8. to 10,000 nails a day and it is on the increase." 
1806 October. (Jefferson to Edmund Bacon). "Those who work in the nailery are Moses, Wormley, Jame Hubbard, Barnaby, Isbel's Davy, Bedford John, Bedford Davy, Phill Hubbard, Bartlet, and Lewis. They are sufficient for 2 fires, five at a fire."
1806. "Jim makes 15 pounds. 20d Nails Barnaby makes 10 pounds, 10d do. Wagner Davy makes 10 pds. 10d do. Bedford John makes 8 pounds. 8d do. Bedford Davy makes 6 pounds. 6d do. Bartlet makes 6 pounds. 6d do. 4 Boys makes 8 pounds. 6d [total] 63 pounds nails"
- ↑ PTJ, 28:341.
- ↑ Ibid, 28:405-406.
- ↑ Bear, Jefferson at Monticello, 53.
- ↑ Overseer's account of daily task of nailers.