FAQ: What ASTM Industrial Test Methods should be used for Visual and Instrumental APHA Color
Answer:
There are many industrial methods that reference the APHA/Pt-Co/Hazen color scale but two of the best are:
- ASTM D1209 Standard Test Method for Color of Clear Liquids (Platinum Cobalt Scale) defines the visual APHA/Pt-Co/Hazen color scale for yellowness of clear liquids.
- ASTM D5386 Standard Test Method for Color of Liquids Using Tristimulus Colorimetry defines the instrumental method of APHA/Pt-Co/Hazen color measurement for yellowness of clear liquids correlated to the visual ASTM D1209 method.
ASTM American Society of Testing and Materials, West Conshohocken, PA USA www.astm.org
The instrumental method provides an objective quantification of the APHA Color Scale with much better precision than the visual method, particularly for near colorless samples.
When APHA/Pt-Co Color is reported you may see references to the ASTM D1209 visual method when an instrument is being used, or occasionally ASTM D1209/D5386 which is more correct. Our statement would be that all HunterLab sphere instruments measure the visual ASTM D1209 APHA/Pt-Co Color scale in accordance with the instrumental ASTM D5386 method.
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