A method of controlling the formation of crocodile skin surface roughness in continuous casting of thin cast strip of plain carbon steel comprising the steps of: assembling a pair of counter rotating casting roils laterally to form a nip between circumferential casting surfaces of the rolls through which metal strip may be cast, the casting rolls having casting surfaces with projections; forming a casting pool of molten metal of carbon steel of less than 0.65% by weight carbon supported on the casting surfaces of the casting rolls above the nip; assembling a rotating brush peripherally to contact the casting surface of each casting roll in advance of contact of the casting surfaces with the molten metal capable of cleaning residual from the surface of the casting roll; cleaning the casting surface of the casting rolls (1'2) with the rotating brushes, the cleaning step including controlling the energy exerted by the rotating brushes against the casting surfaces of the casting rolls to provide a desired degree of cleaning of the casting rolls so that a majority of projections on the casting surfaces are exposed and provide wetting contact between the casting surfaces and the molten metal of the casting pool during a casing campaign to control the formation of crocodile skin roughness on cast strip, the cleaning step including (i) measuring an initial heat flux from molten metal to surfaces of the casting rolls when the casting surfaces are clean surfaces, (ii) thereafter: continually or intermittently measuring the heat flux from the molten metal to the casting surfaces of the casting rolls in real time as a casting campaign continues; and (iii): controlling the energy of the rotating brushes against the casting surfaces of the casting rolls based on the difference between said real time measured heat flux and the initially measured heat flux between the molten and the casting surfaces; and counter-rotating the casting rolls such that the casting surfaces of the casting rolls each travel toward the nip to produce a cast strip downwardly from the nip. assembling a pair of counter rotating casting roils laterally to form a nip between circumferential casting surfaces of the rolls through which metal strip may be cast, the casting rolls having casting surfaces with projections; forming a casting pool of molten metal of carbon steel of less than 0.65% by weight carbon supported on the casting surfaces of the casting rolls above the nip; assembling a rotating brush peripherally to contact the casting surface of each casting roll in advance of contact of the casting surfaces with the molten metal capable of cleaning residual from the surface of the casting roll; cleaning the casting surface of the casting rolls (1'2) with the rotating brushes, the cleaning step including controlling the energy exerted by the rotating brushes against the casting surfaces of the casting rolls to provide a desired degree of cleaning of the casting rolls so that a majority of projections on the casting surfaces are exposed and provide wetting contact between the casting surfaces and the molten metal of the casting pool during a casing campaign to control the formation of crocodile skin roughness on cast strip, the cleaning step including (i) measuring an initial heat flux from molten metal to surfaces of the casting rolls when the casting surfaces are clean surfaces, (ii) thereafter: continually or intermittently measuring the heat flux from the molten metal to the casting surfaces of the casting rolls in real time as a casting campaign continues; and (iii): controlling the energy of the rotating brushes against the casting surfaces of the casting rolls based on the difference between said real time measured heat flux and the initially measured heat flux between the molten and the casting surfaces; and forming a casting pool of molten metal of carbon steel of less than 0.65% by weight carbon supported on the casting surfaces of the casting rolls above the nip; assembling a rotating brush peripherally to contact the casting surface of each casting roll in advance of contact of the casting surfaces with the molten metal capable of cleaning residual from the surface of the casting roll; cleaning the casting surface of the casting rolls (1'2) with the rotating brushes, the cleaning step including controlling the energy exerted by the rotating brushes against the casting surfaces of the casting rolls to provide a desired degree of cleaning of the casting rolls so that a majority of projections on the casting surfaces are exposed and provide wetting contact between the casting surfaces and the molten metal of the casting pool during a casing campaign to control the formation of crocodile skin roughness on cast strip, the cleaning step including (i) measuring an initial heat flux from molten metal to surfaces of the casting rolls when the casting surfaces are clean surfaces, (ii) thereafter: continually or intermittently measuring the heat flux from the molten metal to the casting surfaces of the casting rolls in real time as a casting campaign continues; and (iii): controlling the energy of the rotating brushes against the casting surfaces of the casting rolls based on the difference between said real time measured heat flux and the initially measured heat flux between the molten and the casting surfaces; and counter-rotating the casting rolls such that the casting surfaces of the casting rolls each travel toward the nip to produce a cast strip downwardly from the nip.