The viscosities of melts of L63, L68, LS59-1A brasses and M2 copper are studied. Their samples were taken from the charge materials and solidified ingots in the OAO Revda Nonferrous Metal Treatment Plant. The microstructures of the ingots were analyzed earlier by traditional metallographic methods. Metallurgical defects of the following three types were detected: exogenous nonmetallic inclusions, segregation inclusions, and discontinuities and pores.