FIELD: production of mats. SUBSTANCE: nonwoven mat has density (weight per unit of surface area) variable in crosswise direction, with edges of mat having lower density than basic part thereof. Method involves passing mat forming net through inorganic fiber-liquid suspension, with portion of mat forming net corresponding to edge of future mat being protected during passage thereof through said suspension and with protection extent being variable along length of mat forming net during passage thereof through said suspension; urging said suspension to move toward mat forming net with resulting passage of liquid through mat forming net and formation of nonwoven mat of inorganic fiber having non-homogeneous transverse density (weight per unit of surface area). Apparatus has source of inorganic fiber-liquid suspension, mat forming net adapted to be moved through said source so that liquid is urged to flow through mat forming net and inorganic fibers are settled on mat forming net, protective device extending along part of width of mat forming net corresponding to edge of future mat to prevent said suspension from passage through said part of mat forming net, with protective effectiveness being variable in direction of movement of mat forming net through said source. Cemented cardboard has sheet of nonwoven mat of inorganic fiber placed under at least one surface, with permeability of mat for cementing suspension being variable in crosswise direction of mat. Method and apparatus are used for production of mat from, for example, fiber glass and employment of mats in construction materials such as gypsum cardboard. EFFECT: increased linear speed of gypsum cardboard production line, increased strength of gypsum cardboard due to use of mats having small diameter and reduced amount of cavities in cardboard edges. 11 cl, 3 dwg
