CMR-2976 - RSIN Reflectance Specular Included or RSEX Reflectance Specular Excluded mode?

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FAQ: "One of our customers just upgraded from a ColorQuest XE (with Universal software) to a UltraScan VIS.

They measure powders on the ColorQuest XE and are going to measure the powders on the USVIS using the CMR-2976 24-mm Vial Reflectance Holder.

What methodology should they use – RSIN or RSEX?

How comparable will the results be?"

Normally the RSEX Reflectance Specular Excluded mode is recommended to measure any material behind a flat glass or plastic window as this measurement mode negates the specular gloss or shine off the first surface of the glass/plastic window from the measurement. The specular gloss or shine off the container window is not related to the color of the material and so it makes sense to negate it from the measurement.

The difficulty is that the glass vial has a curved surface which tends to spread the specular making RSIN Reflectance Specular Included mode a better choice. This, in combination with the SAV (Small Area of View) makes RSIN the better choice for a repeatable measurement as described in the enclosed CMR-2976 addendum.

To verify, make 5 sample measurements of the powder in the vial with replacement (lifting the vial out of the holder and putting it back in). Do this for both RSIN SAV and RSEX SAV modes. Whatever measurement mode produces the most repeatable (smallest range) in color values, is the best mode to use.

I do not expect agreement in absolute color values between CLFX and USVIS in measuring powder in the vial but they should agree well in terms of differences.

As the UltraScan VIS and ColorQuest XE are very similar instruments, inter-instrument agreement in color values using the same mode - RSIN + SAV, should be good.

 

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