what is joint compound used for

Joint compound is a white powder material that is mixed with water to form a paste with a spreadable consistency similar to mud. It is primarily made of gypsum dust mixed with water to form a paste the consistency of cake frosting, which is spread onto drywall and sanded after dry to create a seamless base for paint on walls and ceilings. Joint compound is used to finish gypsum panel joints filled with paper or fiber joint tape, corner bead, trim and fasteners, and to skim coat. It is also used as an alternative to traditional plastering to finish joints, corner beads, trims, and fasteners. Joint compound can help hide seams along walls leaving them ready for painting. It can be used to hide just about any type of seam along a wall, even corners where the walls meet. Joint compound is also convenient for patching holes, bumps, tears, and other minor damage to existing walls. It is sold premixed in 1-quart to 5-gallon containers or in a powdered form that can be mixed with water.