The "Silk"
The sailor's black silk "handkerchief" worn round the throat, is of far greater antiquity than as a sign of mourning for Lord Nelson. Originally it was worn in action either round the brow to prevent sweat running into the eyes, or as a general purpose sweat rage, or as a pad to cushion the body against hard knocks or chafe. Nowadays it is only a traditional piece of uniform clothing.
Commonly known as a "Silk", it was, until 1935, a square of black silk 36" square, worn with two diagonally opposite corners knotted together (the knot being worn at the back of the neck beneath the collar, and bight (known as a "Duff Bag") being secured in the tapes of the jumper), so that a drowning man's rescuer would have an efficient handgrip. The new pattern silk introduced in 1935 measures 50" x 12"; since 1942 it has been made of rayon. The uniform regulations require the ends of this scarf to be stitched together, thus forming a loop, for the same reason as the old square silk was knotted into a loop.