Each of the non-originating mills now has to establish their own Reference Standard made on their own machine with their process variables. The Reference Standard has to be an acceptable match to the Master Standard visually and with the chosen color measurement system on a properly calibrated, standard instrument by all interested parties. It may be necessary to have different technical directors, the sales technical support people, and even key customers approve these Reference Standards and how they relate to the Master Standard.
Once the Reference Standard is established in each of the non-originating mills, this becomes the standard for that non-originating mill to use for judging if they have a match for future runs of that grade. Preservation of the Reference Standard samples should be done in the same way as the Master Standard samples.
Note: Why perform this step of establishing a mill specific Reference Standard? Color matching problems of this type have several problems, but one of the most difficult is separating two issues:
- The problem of matching any outside standard from another mill with different processes and different additives. This is the most difficult match and if done with this procedure only has to be done once.
- The problem of matching any internal standard from your own mill from one day to the next, one month to the next, or one year to the next.
For more information on practical aspects of paper color matching, contact me at firstname.lastname@example.org.