How does ink thickness change the appearance of printed color?

We typically focus on color as it relates to displays here at dot-color, but I came across a fascinating post about color in the print industry from John the Math Guy that I had to share. In this post, John takes a close look at how ink looks at different thicknesses and uncovers the reasons for some seemingly unconventional color-naming habits in the print industry.

What happens when we double the amount of ink on the paper? …it would seem that the thick layer of magenta is a lot closer to red. The plot below shows the actual spectra of two magenta patches, one at a larger ink film thickness than the other. The plot leads one to the same impression – that a thick layer of magenta is closer to red in hue than a thin layer.

Chart shows different spectrums of thick (red line) and thin (blue line) layers of magenta ink.

Read the whole thing here:  http://johnthemathguy.blogspot.com/2012/09/why-does-my-cyan-have-blues.html