The JJF (Mechanical) 061-2009 Black and White Diffuse Density Meter calibrating specification provides a detailed specification for the calibration method of black and white diffuse transmission Density Meters. The standard is designed to ensure that Density Meters provide accurate and consistent measurement results in the measurement process, eliminate equipment errors and ensure their measurement accuracy. The steps for Density Meter calibrating, the required equipment, and the reference materials and environment requirements used in the calibrating process are described in detail. This specification applies to black and white diffuse transmission Density Meters in the fields of laboratory, production and quality control to ensure that the measurement results comply with relevant national and industry standards and regulations, and to ensure the accuracy and reliability of Density Meters.