After the coating is applied to the surface of the steel drum with a certain thickness, it undergoes physical volatilization or chemical oxidative polymerization to form a solid film. The time required for such a process is called drying time. This process is divided into two phases:
(1) Dry surface: When the coating film forms a microfilm layer from the fluid to the surface of the steel drum, it is called surface drying. There are two methods for measuring the dry time, namely, the blown ball method and the finger touch method. The blown cotton ball method is to gently put a cotton wool ball on the surface of the coating film, the mouth is 10 to 15 cm away from the cotton ball, and the cotton ball is lightly blown horizontally. If the cotton ball can be blown away from the surface of the coating film without leaving the cotton thread, it is considered It has been dry and sticky, but no paint sticks to the hand, it is also considered to be dry.
(2) Dry: When the coating film forms a solid film layer from fluid to all, it is called solid dry. The method of measuring the dry time is a filter paper method, a cotton ball method, a blade method, or the like. Now introduce the most convenient blade method: the film can be scraped on the sample plate with the safety blade, and the bottom layer of the film is not sticky, that is, the film is considered to be solid.