Negative Space - Areas not used properly resulting in loss of that space, such as air bubbles in bronze and plaster casting.
Nichrome - Metal that can withstand high degrees of heat. Wire used in firing ceramic beads.
Nickel - Metal used extensively in alloys as a catalyst.
Nonferrous - Containing no iron.
Notches - Used in the side walls of a plaster mold to prevent shifting when casting is poured.
Noxious - Harmful to humans.