Since antiquity, humans used basic hand tools such as a hammer and chisel to engrave metals such as nickel, copper and gold, along with man-made combination metals such as brass. A small hammer and chisel made of hard material such as stone, bone or diamond is fashioned into a tool called a chisel, often referred to as a graver, and the engraver uses a small hammer to tap the graver into the metal to fashion the desired design. The engraver must use both hands to cut into the brass.
Engravers use a variety of gravers. While the hammer and chisel method uses a flat chisel, the push graver method utilizes a pointed-tip graver, which fits into a wooden handle and is held in the palm of the engraver’s hand. The brass is held down by clamps or a vise and the engraver uses one hand to drive the graver through the brass to create the design by using pressure from his hand, explains the Engraving School website.
To create a flatter design, engravers often use acid to etch brass. To create the design, a layer of wax or another coating referred to as "hard ground" is applied to the brass to protect areas that the engraver desires to leave plain. A sharp graver is used to scratch the metal where lines will appear on the finished design. The engraver then dips the brass into an acid bath, which eats into the metal where the engraver drew the lines. The engraver removes the acid with a solvent after the lines have set. The brass is then readied for inking if the engraved design requires definition. The excess ink is removed and the wax is removed from the non-engraved area of the brass.
Sugaring is another old method used to engrave brass. A thick sugar syrup is painted onto the brass, the solution also referred to as a "liquid ground," and then the brass is dipped into a solution of ferric chloride to etch the metal where the sugar solution was not applied. The benefit of using ferric chloride over acid is that the ferric chloride does not produce toxic gasses during the chemical reaction with the metal. The engraver then dips the brass into hot water to rinse off the sugar and stop the reaction.