7-2 Color Measurement Notes 01/03
More on Sample Presentation to the Instrument
There are a variety of techniques that can be used in handling various forms of objects and materials so
that the most valid and repeatable measurement of their appearance results. For example, when
measuring the color of a sample, such as fabric, that is translucent, the sample should be folded into
multiple layers to make it appear more opaque. Other materials, such as liquids or semi-solids, might be
read through the glass of a sample cup which presents a flat surface to the instrument.
Examples of ways to measure several types of samples are given below.
Directional Samples
Directionality can be minimized by averaging several measurements with rotation of the sample
between readings. Examination of the standard deviation displayed with the averaging function can
guide you in selecting the appropriate number of readings to average.
Non-opaque Samples
Non-opaque samples must have a consistent backing. A white uncalibrated tile or sample clamp is
recommended. If the sample is such that it can be folded to give multiple layers, such as tissue or lace,
the number of layers used for each measurement should be noted. Translucent samples should be
measured with a larger port opening than illumination area (if VSI was purchased) to allow light to
escape. Light trapped in the sample can distort the color.
Fluorescing Samples
For some applications, the elimination of fluorescence from a measurement is important. Fluorescence
is caused by ultraviolet (UV) excitation of the sample, where a material absorbs nonvisible wavelengths
of energy and re-emits the energy as light in the visible spectrum. Since UV light is part of the normal
sample illumination, measurements may include UV excitation. To eliminate fluorescence from the
measurement, place the UV filter (if purchased) over the sample port or use the UV control feature.
The LabScan XE measuring
fabric.
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