Color Part III

In the pervious two parts we discussed the definitions, in this segment let us start the discussion for the matching of color, or the selection process for a matched color.

When in effect we wish to match a color whether it is for a concentrate or pre-colored material, there are two things that are of a concern.

1- Commercial or critical match. What this means is what the range of color and shade are we matching to.  If in fact you think of a range with a mid-point and than a plus and minus range to meet the expectations of the color. Thus the color may be off the match point but within specification as far as manufacture of that color is concerned.  This is where a commercial match and critical match differ, in the amount of the range.
2- What is the color you are matching? It is by far; better and easier to match to a Pantoneâ color number than to a part. Thus we start with the true midpoint of the color and the ranges that would be acceptable.  If in fact we started with a part, paint chip, color swatch, which all can be done, we now possibly have a new midpoint.

Problem

1- When matching to a part or previous produced part the main concern is that it is not at the midpoint but is acceptable. We than have a match with this color as the midpoint and now have a range above and below this chip. The upper range would possibly be out of the total range for the existing color but within specification to all that was matched. The example below well try and illustrate this problem.
 

As can be seen from the above, the midpoint of the new match is still within the original range. But the upper range of the new match falls out of specification of the old original range. This is a more common problem than people realize especially when people use old parts that were not protected from fading and color shift due to UV exposure.

Thanks for the time, to be continued.

Steven L Silvey
Sr. Technical Service
General Polymers Division
Ashland Distribution Company