How much plastering did the slaves do?

"Plastering began at the Capitol in the fall of 1798 as soon as the interior rooms were bricked and lathed. Work continued through the fall of 1800. The contractor, John Kearney started with 10 workers. The commissioners ordered him to hire more and gave him 3 more hired slaves to help. On average, 4 or 5 of them worked with the plasterers, amounting to 65 ½ months of work. Here too the commissioners charged the contractor $16 a month for the hands. We don’t know exactly what the hired slaves did save that in June 1799 the commissioners ordered a ½ pint of whiskey a day for the slaves boiling plaster of Paris."

Quote from Slave Labor in the Capital, page 148

We do not have the payrolls of the contractors so we don't know how many slaves they used, if any, unless, as in the case of Kearney, they hired slaves from the commissioners. We know that slaves worked as plasterers. Clotworthy Stephenson, an associate of James Hoban, who lived near the White House noted that his runaway slave Will was both a bricklayer and plasterer. 

While I found little information on Kearney, there was another contractor who came to the city in 1796 to do plastering, Hugh Densley. He contracted with Robert Morris and John Nicholson to plaster the houses the speculators were having built mostly in southwest Washington. The speculators arranged for Densley to rent 21 "temporary buildings". He would pay the rent with plasterers' work.

There were different rents for the "temporary buildings," varying from $12.16 to $60.76. How the rents for temporary structures likely made with wood could vary so much is puzzling, probably had to do with floor space. 

I share this document from Nicholson's papers for two reasons. It shows the scale of Morris's and Nicholson's operations and shows that skilled workers had to be housed some likely with their families. I think it more likely that Densley recruited free workers from Baltimore or other cities to come to work for him, rather than recruiting slaves from area masters. Both free and slave workers had to be housed but slaves could be forced to sleep in spaces that would have cost Densley far less money. I should add that the bankruptcies of Morris and Nicholson probably stymied the fulfillment of the bargain described in the letter. The whole story might be found in Nicholson's papers.