This instrument is used to objectively measure the color of a surface. This is a useful measurement in experiments examining surface appearance changes before and after treatments or weathering. We commonly use calculations from these data to determine the absolute change in a sample’s color across the duration of an experiment.

Konica Minolta Chromometer 400 

Alex Beard using colorimeter in a sensor-up configuration

This instrument can be used to take color measurements relative to a variety of color-spaces used for identification, including (but not limited to) L*a*b*, Munsell, Hunter Lab, and XYZ.  We most commonly use the L*a*b* measurement parameters, which describes a surface’s color relative to the brightness-darkness axis (L*), the red-green color axis (a*) and the yellow-blue color axis (b*).  This provides an objective measure of color in three values, which can locate the color in three-dimensional space.  The L* values range from 100 (bright) to 0 (dark); the color axes have positive or negative numbers toward each of the color extremes, with 0 being neutral gray.  When we take measurements at multiple points throughout an experiment, we can calculate the absolute change in color.

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Graphical representation of the three axes measured by the chromameter

The Konica Miolta Chomometer is one of our most regularly used instruments and is currently being used in studies of crude oil removal from historic materials, herbicide effects on building materials, and aging of adhesives used in fossil conservation.

 

 

 

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National Center for Preservation Technology and Training
645 University Parkway
Natchitoches, LA 71457

Email: ncptt[at]nps.gov
Phone: (318) 356-7444
Fax: (318) 356-9119