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Harmonisation of national scales of surface colour measurements

Objective



Background

Surface colour measurement is of importance in the
production of a very wide range of manufactured goods.
Industry needs to be able to measure colour within the
limits of the human eye, about 0.5 CIELAB units. An
earlier European intercomparison of surface colour
measurements showed that 50% of colour measurements made
by national standards laboratories did not agree within
this limit. A reduction in uncertainties of colour
measurement is needed to improve competitiveness in the
trading of coloured goods.

Objectives

The overall objective is to reduce the errors in colour
measurement so that 95% of colour measurement by the 9
participants agree to within 0.5 CIELAB units. This will
be achieved through the use of a system for determining
and correcting errors in colour measurement followed by
an intercomparison of non fluorescent surface colour
measurements. An intercomparison of fluorescent colours
will also be carried out by 3 of the participants.

Work Programme

The coordinator has developed techniques for determining
and correcting errors in colour measurements as well as a
range of transfer standards for colour as part of a
national programme on colour measurement. The
methodology of determining and reducing colorimetric
errors will be used by all participants who will then
meet to refine jointly the methods to achieve
harmonisation of measurements to the required level. An
improvement of a factor of 4 over current levels of
agreement is being sought. Ten difference steps in the
technical process have been agreed. Following the
determination and correction of errors each participant
will measure 9 matt colour standards and 9 glossy colour
standards and then calculate their colour specifications.
Three participants will also measure 4 fluorescent
standards by the two monochromator methods. One of these
participants will develop a two monochromator system
prior to the intercomparison.

State of Progress

The programme commenced on 1 February 1997 and will last
3 years. Participants met and agreed a common
methodology. The coordinator purchased and calibrated
the artefacts necessary for the determination of errors.
These have been dispatched to the other participants in
part 1 of the project together with instructions on
determining and correcting errors, model software for the
calculation of colorimetric data and instructions on the
handling and cleaning of materials. Participants are now
determining their measurement errors using the calibrated
artefacts. A detailed report from one of the
participants giving results on the determination of all
the errors has already been received. A report on
progress in the development of a two monochromator
instrument has also been received.

Call for proposal

Data not available

Coordinator

National Physical Laboratory (NPL)
EU contribution
No data
Address
Queen's Road
TW11 0LW Teddington
United Kingdom

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Total cost
No data

Participants (8)