PURPOSE: To easily form the fluorescent film for a cathode-ray tube with high density by adjusting a liquid quantity infected into the bulb of a cathode-ray tube and installing the bulb of the cathode-ray tube into a centrifugal separation means in the condition of setting bulb weight containing a liquid to a predeter mined constant value.

CONSTITUTION: A coating liquid in which barium acetate is dissolved in pure water is infected into a bulb for a cathode-ray tube. Next, the weight of the bulb itself for a cathode-ray tube is measured in advance with respect to any samples to estimate the minimum value, for instance, the minimum value + the weight of a coating liquid -10g is set for the reference value of the gross weight of the bulb for a cathode-ray tube in which the coating liquid is infected to set it in the limit setting mechanism part of an automatic weighing machine. After that, a pipe descends, and the coating liquid of the weight corresponding to a difference from the reference value is discharged into a discharge liquid tank. After that, a predetermined fluorescent liquid is infected into the bulb. Next, a fluorescent powder is made to adhere to the surface of a panel to form a fluorescent film.