My first experience with the Munsell Book of Color was on a dig in Olduvai Gorge, Tanzania, Africa, during my field school. The field director asked me to Munsell a profile and I had no idea what he was talking about. He then told me that it was a British thing. They always Munsell soil samples and profiles. I later learned that it is not, of course, a British thing. Still not sure why he said that.
This post is for people that use Munsell Color Books everyday and also for those that have never heard of it. Honestly, I never really understood what the different pages really meant and what the value and the chroma are. Maybe you learn that in art class but I haven’t had an art class since second grade. For those of you that know everything, here is an Indiana Jones / Cat thing. For everyone else, prepare to geek out.
The Munsell color system specifies colors based on three dimensions: hue, value, and chroma. For non-art majors, I’ll explain what these are. Hue is defined as “the degree to which a stimulus can be described from stimuli that are described as red, green, blue, and yellow”. Other definitions state that hue is a “pure” color without tint or shade. In the Munsell system there are five principle hues: Red, Yellow, Green, Blue, and Purple. There are five intermediate hues which create a total of 10 hues which are then broken up into 10 more hues each for a total of 100 hues. Those hues are given values. Figure 1 illustrates where the popular hues, the few that archaeologists typicaly use, lay on the color wheel.
The next metric, value, refers to the lightness of a color. In the Munsell system it is measured vertically from a value of 0 (black) to 10 (white). The colors from black to white, including the various shades of gray in-between, are called neutral colors. All other colors are called chromatic colors. We’ll see why below.
The third metric, chroma is measured from the center of color system, horizontally, and represents a color’s purity. A lower chroma is washed out, such as in pastels, and a higher chroma is brighter. There isn’t necessarily an upper limit for chroma. Some hues have a higher potential chroma than others. For example, light yellow colors have a higher potential chroma than light purples do because of the nature of the human eye and the physics of color stimuli. Normal reflective materials have a chroma into the low 20s while some fluorescent materials have chroma values as high as 30.
So what does this all mean for archaeology? Well, most of it doesn’t mean a whole lot. We use a very small wedge on the Munsell Hue wheel. I just feel that it’s good to know the details about the things we use every day.
Where did the Munsell Color System come from?
The idea of using a three dimensional shape to represent all possible colors was first explored in the mid-1700s. Several shapes were chosen including a triangular pyramid, a sphere, a hemisphere, a cone, and a tilted cube. The most sophisticated design was a slanted double cone conceived of by August Kirschmann in 1895. Kirschmann’s color solid was the first to recognize the difference between bright colors of different hues. All of these models encountered problems when trying to accommodate all possible colors and none were based on the measurement of human vision.
Albert Munsell, a professor of art at the Massachusetts Normal Art School, wanted a way to describe color that would use decimal notation instead of color names which could be misleading. He started on his new system in 1898 and finished it seven years later in A Color Notation in 1905.
The first Munsell Book of Color was published in 1929 and improved on deficiencies regarding the physical representation of the theoretical system. Experiments performed by the Optical Society of America in the 1940s resulted in improvements to the system and the familiar notations that we know today.
The Munsell system today is used, not only for archaeology, but for skin and hair colors in forensic pathology, matching soil colors for the USGS, shades for dental restorations, and in breweries for matching beer colors. I thought that last one would get your attention.
Want your very own Munsell Book of Color? The full book will cost you. The full book, with over 1,600 color chips (in glossy or matte) is $945. You’ve probably never seen the full book. I never have. That’s because they sell a soil version. The Munsell Washable Soil Color Charts (2009 Edition) runs for about $185. You can find it at the previous link or at Forestry Suppliers, among others. The Munsell Store also sells a pack with just the 7.5YR and the 10YR page for an astonishing $75.
Alternatively, you can buy the $4.99 iOS app for your iPhone. Check out the post here.
Hope you learned something! See you in the field.