- May 1, 2020
- Posted by: Konica Minolta
In the chemical industry, APHA color, also referred as Platinum Cobalt (Pt/Co) scale or Hazen, is commonly used for liquid chemical products that are clear or slightly yellow tinted. But for liquid chemical which has a higher degree of yellowness, a separate scale like Gardner color scale is required.
The Gardner color scale is a well-established method for evaluating the color of oils, oil-based varnishes, clear laquers, fatty acids and liquid chemical products which are yellowish to reddish. The earliest form of this scale consisted of 18 standard solutions where each comes in a slightly different shade, ranging from light yellow (Gardner 1) to red (Gardner 18).
These formula prepared liquids, however, were vulnerable to unstable color variation over time and requires regular preparation to maintain its traceability. To improve precision, standard made of colored glass was introduced.
Both the liquid and glass scales rely on human judgement by visually comparing sample against the Gardner color scale. This method is highly subjective as color perception differs among individuals. Moreover, surrounding background and ambient lighting can affect visual judgement.
Objective and consistent evaluation can be obtained using color measuring instruments like Spectrophotometer CM-5. Preloaded with common industrial standard color scales like Gardner color, APHA/Hazen and Iodine Color Number, and CIE Color Systems like CIE L*a*b* and L*C*h, CM-5 provides a simple, fast and comprehensive solution to chemical color measurement.
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