CLM-194
User Guide
EOPTIS SRL
Via Alto Adige, 152 – 38121 Trento (TN) – ITALY
Tel.: +39 0461 260 552 – Fax: +39 0461 260 617
www.eoptis.com – [email protected]
Page 8 of 29
CLM-194
Rev. 1.05 - 06/2014
Copyright © 2013-2014 EOPTIS SRL
Translucency by a non-opaque sample is often the main source of error. Part of the light incident on a translucent
sample penetrates the surface and undergoes internal scattering and lateral diffusion, which reduces the intensity of
reflected light. Ambient light might also penetrate the instrument port and affect the measurement in an uncontrolled
way. A translucent sample must be made as opaque as possible either by increasing the thickness and/or by backing it
with an stable and durable opaque material (usually black or white). The chosen thickness and baking material should
be logged in measurement report to ensure repeatability.
To select a sample which adequately represents the part under evaluation, examine a sufficient number of random
samples from the lot, and average the readings.
In case of an uneven surface, the instrument optically averages the colour on the area corresponding to the
measurement spot. For longer range non-uniformities, it is recommended to average several measurements taken at
different positions on the sample to find the closest match (see the Multiple Acquisition feature in §5.9.3).
Textured surfaces can be presented to the instrument at any orientation. The circumferential illumination allows
reading which is unaffected by sample orientation. In very limited cases where the surfaces are highly textured, it is
recommended to turn the sample and check differences on multiple readings.
Several published standards address sample selection for various industries (fibers, yarn, liquids, powders, coatings,
paints, papers, leather, etc...). Contact Eoptis for additional information and support in identifying the best technique
to exploits the full performance of the colorimeter.
Repeatable and accurate measurements may be difficult or impossible to obtain if some samples have any of the
following characteristics:
a surface which contains fluorescent pigments or appears unusually bright
an appearance which changes based on the point of view (may contain metallic, flake, or pearlescent
colorants)
a very curved, highly uneven or corrugated surface.
