ASTM E313-2005 Whiteness and Yellowness

Many customers will ask us why i didn't get value in WI or YI like this image: 

Because WI has some measurement requirements like D65 light source or C light source. We should measure this WI value under D65 or C light and observe angle 10 degree or 2 degree. 10 or 2 degree are all ok. 

Once we display XYZ and TI value here. 

It showed TI value is over +- 3. 

But in international standard ASTM E313-2005, WI requires -3 < T < +3 then it will show WI value and it has a meaning or it has no meaning for this sample to measure WI. 

Here is the light source requirement for WI and YI. 

When customers want to measure Yellowness, they should choose D65 or C light source, then they will get YI value, while when customers want Whiteness or Tint value, they have to choose C or D50, or D65 light source. 

Different light sources WI, YI value should be different. So that is why some values display and some values disappear. 

Hope this post is useful for customers to check WI/YI. 

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