Gypsum crack fillers are universal joint sealants used for jointing, caulking, leveling and bonding between gypsum boards, ready-mix materials made by certain production processes of inorganic or organic cementitious materials, fillers and various chemical admixtures. Finished products of ready-mix materials include two kinds. One is powdery, called caulking gypsum powder; the other is pasty, called plasterboard joint compound (joint compound for short). Caulking gypsum powder is a ready-mix powder material prepared with building gypsum as the base material and containing a variety of chemical admixtures, which can be used on the site after mixed with water into paste. This kind of joint treatment is characterized by a large bond area and a layer of joint area combined firmly with putty in the middle. When the board surface is under the effect of load, then stress will be confined to a single gypsum board surface. It is not easy to crack, forming an overall strong, firmly bonded, flat and smooth wall. Therefore, such a type of crack filler cured by hydration of cementitious materials is also known as solidified crack sealant. Joint compound is a paste colloidal material made by the compound of polymer emulsion as the base material with special chemical admixtures and powder fillers added. This kind of joint treatment is characterized by flexible connection for the jointing layer. When the board surface is under the effect of load, stress will be distributed on the entire board surface. It is not easy to crack, forming an overall wall in combination of rigidity and flexibility. Therefore, this type of crack filler cured by water loss of cementitious materials is also known as dry crack sealant. Caulking gypsum powder is a powder material ready mixed by many kinds of materials. It needs to mix with water into operable paste crack filler for such joint treatment as caulking and leveling. After hardening, it enables the surfaces of gypsum boards into one. It is featured with good workability, appropriate stickiness, ease of coating, enough time for use, fast hard drying, no shrinkage, solidified crack filler, ability to fully fill the cracks between boards of different thickness, and no cracks. Since full filling helps increase the sound reduction index and fire resistance, it is a general-purpose joint sealant suitable for jointing between all kinds of gypsum boards, with suitable bonding performance, enabling crack fillers to be tightly bonded with plasterboards, gypsum core materials and jointing areas, etc., as well as superior fire resistance and strength to plasterboards.