Saggar refers to a structure that encloses a piece of pottery for firing. My pieces are burnished or polished wit terra sigalata then bisque fired. Copper wire is glued to the surface. Pieces are then dipped or spayed with chemicals for colorants then sprinkles with salts, copper carbonate, salt soaked straw, etc. Then they are wrapped in heavy duty aluminum foil. Firing takes place in gas kiln for about four hours then allowed to cool overnight.