Geosynthetics July/August 2024 - 43

Color is described as what someone sees
when light is reflected from an object at
a different wavelength; the brain then
interprets these signals.
Colorimeters help measure the color
of the geosynthetic by using " L, " " a " and
" b " values. It is important to know what
these values mean. The colorimeter can
be set to measure single points on a surface
or compare two parts against each
other. The values are as follows:
* The " L " refers to the lightness of the
part ranging on a scale of 0 to 100.
Zero is pure black (dark) and 100 is
pure white (light).
* The " a " refers to the red-green range.
A negative " a " value is green and a
positive " a " value is red. Zero is neutral
and unlike the " L " value, " a " has no
defined range limit.
* The " b " refers to the blue-yellow range.
A negative " b " value is blue and a
positive " b " value is yellow. The higher
the " b, " the more yellow it is. Like " a, "
" b " also has no defined range limit.
After using a colorimeter, one can use
the calculation of Delta E (ΔE) to combine
all three values to compare to another
sample or a standard coupon. When comparing
two samples, ΔE can give an overall
difference to help determine if the sample
is close in color to the standard. Limits can
be set depending on the application. The
closer to 0, the closer in color. Generally,
the human eye can differentiate anything
over a ΔE of 2.0-3.0. Less than 2.0 is considered
to be a very close color match,
but again, it is dependent on a company's
chosen standard and the application. In
general, geomembranes should be able
to maintain a Delta E (ΔE) of 4 or below.
Each individual sees color differently,
so not every person should make
GeosyntheticsMagazine.com
43
Koerner announces GSI ascendancy plan
One of the big announcements at the 5th Pan-American Conference On Geosynthetics
(GeoAmericas 2024) in Toronto came from George Koerner who announced that he
is stepping down as director of the Geosynthetics Institute (GSI) but is not retiring in
2025. " I'm transitioning but certainly not ending my duties, " Koerner said. " GSI is alive
and well. It will be getting new leadership but I am certainly not retiring. "
An ad hoc committee has been formed to come up with an ascendancy plan
for the future of the GSI. GSI is currently accepting proposals for transitioning its
operations for the future.
GSI's current leadership is aging and its board has agreed that it is time to
transition to new leadership, which will manage the institute going forward. Koerner
explained that the ascendancy may take, but is not limited to, hiring a new director
and staff for its existing location, moving GSI to a new location while still running the
institute as a 501(c) 3 organization, obtaining university affiliation and moving to a
new location near campus, or moving to an affiliate overseas: Bombay Textile Research
Association (BTRA), Fiti Testing and Research Institute (FITI) or the National Pingtung
University of Science and Technology (NPUST).
RFPs are being accepted for this transition. Both a written submittal and oral
presentation will be reviewed and evaluated via a scorecard by GSI's ad hoc ascendancy
committee. If you are interested in submitting a proposal, contact GSI for the complete
proposal document and scorecard. Written proposals are due by September 20, 2024.
Oral presentations will be scheduled thereafter with the ad hoc committee.
decisions on color matching, because
some people differentiate color better
than others. When a color is matched, the
geomembrane should be in its final form.
Color difference can be an MQC tool
to control production and colorfastness
can be used as a durability evaluation.
This method can be used in conjunction
with laboratory or field procedures
for evaluating the relative resistance of
geomembranes to change in color when
exposed to UV radiation or weathering.
The GRI GM-39 test method will help
ensure color conformity among geosynthetic
rolls. We admit that this new standard
has been missing from our repertoire
of test methods for years. However,
the final draft is being reviewed and GRI
GM39 will soon be available as an MQC
and durability check. G
FIGURE 2 Colorimeter obtaining L, a & b
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Geosynthetics July/August 2024

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