Indirect profits from slavery
It was not necessary to own slaves in order to profit from slavery. Many North East merchants made money selling goods to slave owners in the Caribbean.
Two local products regularly shipped to Jamaica were salted herrings and coarse linen cloths called osnaburgs. Plantation owners stockpiled the herrings to feed their slaves, especially when hurricanes destroyed regular food crops such as maize and plantains. They distributed the osnaburgs to their slaves once or twice a year as a basic clothing allowance.
Sugar and rum production provided commercial opportunities too. William Forbes was a successful coppersmith from Aberdeen. Among other products, he manufactured sugar boiling pans and rum stills for export to Jamaica. Some of his business contacts in Jamaica came from his sister’s brother-in-law, Alexander Allardyce. Allardyce was MP for Aberdeen in 1792–1801, but had previously been a merchant in Jamaica. He had, it was said, ‘sold as many black men as there are white in his native city’.
Note: Click images to enlarge

A spinning wheel for turning flax into linen yarn, made at Clatt, Aberdeenshire, in the early 19th century. (© The University of Aberdeen)

Field slaves in Jamaica wear linen clothing issued by the plantation owner. (© The British Library Board)

An Aberdeen customs stamp for linen, 1745.
(© The University of Aberdeen)
It was just like needles when it was new. Never did have to scratch our backs. Just wriggle your shoulders and your back was scratched.
A former slave in Virginia recalls wearing osnaburgs
Sometimes there was a direct link between slavery and Scotland’s whisky distilling heritage. In the 1820s William Shand started distilling whisky at Fettercairn near Laurencekirk using his experience of making rum on his brother’s sugar plantations in Jamaica. For at least ten years he ran parallel experiments in Jamaica and Scotland to improve his rum and whisky production.
By this vessel there are steam apparatus and materials connected with a still on Kellitts Estate. There are also herrings for the several estates, and 73 further barrels for sale.
William Shand ships rum-making equipment and herrings to Jamaica, 1827

A coppersmith with Jamaican connections: William Forbes of Callendar, by Sir Henry Raeburn, 1798.
(Scottish National Portrait Gallery)