If you are like me, you might want to have a lot of colors but may not use all of them that much. Some colors will be unused for months or even years. As an example, my bright green colors are seldom the most used colors but I might want them anyway (or get them in sets unwillingly).
If I compare markers to any other art material that I use, they are without a doubt the most sensitive to aging. Graphite and colored pencils are completely safe to store for a long time, and even watercolors and oil paint can hold for many years.
There are two main things that can happen to a marker over time (except for using the marker).
The first thing is that it dries. The cap may not be secure enough or the barrel might even let air in. The oldest markers I have (that I know for certain) are my old Tria Pantone from Letraset. I think that they stopped their cooperation with Pantone around 2007 so they are at least ten years old. The design of the Tria pantone, that now have become Winsor & Newton Promarker, have proven to hold the ink without any problem. However, I have had markers that dried out before I received them, so I feel that the problem of drying has more to do with the quality of the marker then the aging process. In a large time scale I guess that all markers will dry out, but since alcohol markers isn’t that old, we don´t know yet how long that will take.
The second thing is that the dye in the marker seems to loose its color over time. I bought my first Promarker 2008, in 2010 I bought my first Copic, and the following years I bought a lot of different markers. I luckily made a color chart of all the markers I had in 2011 so I can compare with them I have left. Some brands have undergone a great value and hue change. Other brands haven´t change at all.
It is mostly the skin-colors (the Caucasian skin color) and the grays (especially the warm gray) that have undergone a huge change. When the color is fading it is leaving a very light yellow tone or in some cases even more or less a blender. They can still be juicy. I went back to old drawing I have done in sketchbooks with the markers, but nothing has happened to the ink in the sketchbooks. The problems seem to happen in the barrel.
Worst of all brands are Touch. I have some Touch in the old barrel (I think from two generations back) and interesting enough they had some changes but less then in the new barrel (from 2012). I bought the new one when they first where launched, and I guess some of them are from that year. Almost all my skin colors have lost more or less all saturation; they look light yellow or have hardly any color at all (read more here: http://markersguild.blogspot.se/2013/11/touch-twin-marker.html). There are a lot of other brands with the same problem. Some brands that I know haven’t had any changes over time are Kurecolor, Letraset and Neopiko. I write more about them on each and every brand in this blog. Of course, newer brands (and brands I haven´t had for long) have yet to prove whether or not they are prone to the same problem.