Because printing is done in CMYK (Cyan, Magenta, Yellow, and Black) and uses a blend of 4 colors of ink, printed products are subject to small degrees of color variance.
This means that some colors may look slightly different when printed on paper at the start of a large print run, compared to examples from the end of the print run. In addition, these differences may be even more noticeable between print runs.
For this reason, there are a number of recommended CMYK values to help minimise color variance.
We do our best to keep color variation to a minimum. Consequently, however, we cannot always color match against work from other printers.