act or art of communicating a blue colour to bodies otherwise deliquescent thereof. Laundresses blue their linen with smalt; dyers their fluffs and wools with woad or indigo.

Bluing of Metals is performed by heating them in the fire till they assume a blue colour; particularly practised by gilders, who blue their metals before they apply the gold and silver leaf.

Bluing of Iron, a method of beautifying that metal sometimes practised; as for mourning buckles, swords, and the like. The manner is thus: Take a piece of grind-stone or whet-stone, and rub hard on the work, to take off the black scurf from it; then heat it in the fire; and as it grows hot, the colour changes by degrees, coming first to light, then to a darker gold colour, and lastly to a blue. Sometimes they also grind indigo and salad-oil together; and rub the mixture on the work with a woollen rag, while it is heating, leaving it to cool of itself. Among sculptors we also find mention of bluing a figure of bronze, by which is meant the heating of it, to prepare it for the application of gold-leaf, because of the bluish cast it acquires in the operation.

Bluff-headed, among sailors. A ship is said to be bluff-headed that has an upright stern.