A taping knife or joint knife is a

drywall Drywall (also called plasterboard, dry lining, wallboard, sheet rock, gypsum board, buster board, custard board, and gypsum panel) is a panel made of calcium sulfate dihydrate (gypsum), with or without additives, typically extruded between thick ...

tool with a wide blade for spreading

joint compound Joint compound (also known as drywall compound, drywall mud, or mastic) is a white powder of primarily gypsum dust mixed with water to form a paste the consistency of cake frosting, which is used with paper or fiber ''joint tape'' to seal jo ...

, also known as "mud". It can be used to spread mud over nail and screw indents in new drywall applications and is also used when using paper or fiberglass drywall tape to cover seams. Other common uses include patching holes, smoothing wall-coverings and creating specialty artistic wall finishes. Common sizes range from 15cm to 30cm wide (five to 12 inches). Spackle knives are a smaller version, used for patching small holes. A right-angle joint knife allows one to apply joint compound to inside corners where walls meet. The handle is offset to allow clearance for fingers.

References

* ''The Reader's Digest Book of Skills and Tools'' * Josh Mars and His Tips For Home Repairs Mechanical hand tools {{Tool-stub