In Soul by Soul: Life Inside the Antebellum Slave Market, Walter Johnson shows how slaves were adapted to represent their new masters even before they were purchased. Slave traders fed the slaves on high-fat foods such as bacon and butter and rubbed oil into their skins to make them appear healthier. They even invented histories for them, in order to pretend that they had particular skills and aptitudes. They dressed the male slaves in suits and the female slaves in dresses, and ensured that both sexes were well groomed.
All these preparations made the slaves more valuable, but not primarily as laborers. Slaves were expensive, and slave ownership was a sign of high social status, showing that one had joined the ranks of the elite in the Antebellum South. Slave owners defined themselves partly by the number of slaves they owned, particularly if they had large plantations. However, families of the highest status, or those who aspired to such a position, were also much concerned with the appearance and manners of their domestic slaves. Dark-skinned slaves labored in the fields, but slaves who worked inside the house generally had to be light-skinned, and preferably young and healthy-looking. These slaves were often elegantly and expensively dressed and instructed in etiquette and deportment.
The more social graces slaves had, and the more impressive they looked, the better they reflected on the status and social sophistication of their employers. Owners who regarded themselves as philanthropists and benefactors to their slaves were particularly concerned that the slaves should appear well cared for and contented. Similarly, owners who made a display of their own religious piety required the same from their slaves.