Report of the IWTO Colour Working Group
Abstract
In Barcelona, the National Council of NZ Wool Interests raised concerns about the operation of IWTO-56-00 in New Zealand. The sources of the ‘lack of harmony’ of measurements in D65/10 colour space between the NZ test laboratories have been identified and corrected. Instruments used by one laboratory, whilst producing satisfactory results with CERAM reference tiles, produced results on wool samples that were different from the majority of instruments used in the commercial core test laboratories.
Actions have been taken to eliminate the instrumental differences between the laboratories; one laboratory is purchasing alternative instruments and using an alternative measurement cell design. Actions have also been agreed to reduce residual effects caused by differences in sample preparation between the laboratories. It is anticipated that by the Nice meeting, the above actions will have removed the former impediments to reporting of D65/10 tristimulus values on the IWTO certificates for NZ wool as required by IWTO-56. The Working Group recommends that the laboratories begin reporting data in D65/10 colour space on the 3rd December 2002 in accordance with the resolution of the Commercial Regulations Committee in Barcelona.
The Working Group recommends that where wool users require data in C/2 space, this data only be obtained by calculation from D65/10 data using baremes contained in the proposed amendments to the test method.
The Working Group has proposed a number of additional changes to IWTO-56 to simplify its use in testing and to remove the confusing array of options. These proposed changes are contained in Raw Wool Working Group Submission RWG01. In particular, amendments are proposed for the test method to prevent the use of inappropriate instruments in future.
The Working Group proposes that work be continued to assess whether new appendices to IWTO-56 which give additional guidelines to new and existing laboratories to ensure the appropriateness of their scouring and drying techniques used in preparation of samples for testing are required.
It is finally recommended that industry should implement the use of D65/10 measurements fully as quickly as possible so that the reporting of C/2 values can be withdrawn. Subject to further discussion with commercial interests and within the RWG, T&S and Commercial Regulations Committees, it is recommended that the reporting of C/2 values be discontinued on 1st July 2004.
Citation
"Report of the IWTO Colour Working Group", IWTO Colour Working Group, Report 05, Raw Wool Group, IWTO Nice Meeting, November 2002