GB/T 4465-2012 "Basic Dyes - Determination of Shade and Strength" specifies methods for determining the shade and strength of basic dyes, applicable to the quality control and evaluation of various types of basic dyes. The standard includes two testing methods: dyeing method and solution colorimetry. The dyeing method requires visual comparison after dyeing fibers under standard conditions, while the solution colorimetry method measures absorbance based on the Lambert-Beer law. Testing requires instruments such as spectrophotometers, standard light sources, colorimetric tubes, and analytical balances, while adhering to the requirements of relevant normative reference documents. It provides a unified basis for quality assessment of basic dyes in applications such as textiles, paper, and leather.