The acupressure method and the cotton ball method are commonly used to evaluate the drying time of coatings or liquid surfaces. Their differences are mainly reflected in the test principle and operation mode:
Shiatsu:
The acupressure method is to evaluate the drying time of the surface by pressing the coating or liquid surface with your fingers to feel whether it still has stickiness or adhesion. When there is no obvious stickiness or adhesion on the surface of the coating or liquid, the surface can be considered dry. This method mainly depends on human touch and experience, and belongs to the subjective evaluation method.
Blow cotton ball method:
The cotton ball blowing method is to use an air blowing tool (such as a ball blowing pump) to blow air to the surface of the coating or liquid, and observe whether there is adhesion on the surface of the cotton ball to evaluate the surface drying time. When there is no adhesion on the surface of the cotton ball, the surface can be considered dry. This method is more objective than the acupressure method and relies on observation and judgment.
The difference between the two methods is mainly due to the difference in test principle and operation method. The acupressure method is mainly based on touch and experience, and needs to judge the dryness of the surface by the feeling of the finger; while the cotton ball blowing method is more objective by observing the adhesion of the cotton ball surface. Both methods are relatively simple and fast methods for evaluating surface drying, but they are not accurate measurement methods. They can only provide a rough estimate of drying time, and the specific drying time is also affected by many factors, such as coating type, ambient temperature, humidity, etc. For some applications with high drying time requirements, more accurate measurement methods and instruments may be required to assess the surface drying time.