Blackwork is an embroidery technique that dates back to at least the 16th century. It’s also called Spanish Blackwork because it’s thought that it was first brought to England by Catherine of Aragon. It became very popular during the reigns of Henry VIII and Elizabeth I as a decorative element on clothing but gradually lost ground in the 17th century.
If you’ve read The Canterbury Tales by Geoffrey Chaucer you might recall that he describes the clothing of the miller’s wife in this way:
“Of white, too, was the dainty smock she wore, embroidered at the collar all about with coal-black silk, alike within and out.”
The stitches that are characteristic of this geometric technique are Double Running Stitch (also called Holbein Stitch) and Back Stitch. It’s usually stitched on an evenweave fabric.