Standard Test Method for Color of Transparent Liquids (Platinum-Cobalt Scale)

Platinum-cobalt scale is a common color standard test method for transparent liquid, which is used to qualitatively and quantitatively evaluate the color of liquid. The following are the basic principles and operation steps of platinum – cobalt scale:


Platinum-cobalt scale is a set of liquid color standard solutions composed of platinum and cobalt. The platinum-cobalt scale is adjusted by concentration gradient to obtain different color levels, gradually transitioning from colorless to different color depths. The color level of the liquid can be determined based on the color comparison between the liquid and the platinum-cobalt scale.

Standard Test Method for Color of Transparent Liquids (Platinum-Cobalt Scale)

Operation steps:

Prepare platinum-cobalt scale: according to the desired color level, prepare the corresponding concentration of platinum-cobalt scale solution.

Calibration: Place the platinum-cobalt scale under a standard light source and calibrate the conditions for visual perception to ensure accurate color comparison.

Test sample: The clear liquid sample to be tested is compared against the same background as the platinum-cobalt scale. Care is taken to ensure that the temperature and lighting conditions of the sample and the ruler are similar.

Comparison and evaluation: Compare the sample to be tested step by step with the platinum-cobalt scale, find the color level that matches the scale, and evaluate the color of the liquid.

Note: The platinum-cobalt scale is a subjective assessment method, and the results may vary depending on the subjective factors of the observer. Therefore, when color rating is carried out, it is better to have independent rating by multiple observers and average to improve accuracy. In addition, the platinum-cobalt scale can only provide a relative comparison of liquid color, not an accurate color value. If accurate color measurements and comparisons are required, it may be necessary to use professional equipment such as spectrometric instruments or colorimeters.

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