This month, we’re heading back into the studio to take a look at tarnished metal.
Figure 1: Munsell colors for April 2013
The word “silver”, when used as a color description, simply means “neutral”. Silver has no hue, value or chroma in and of itself. Consider this question: what color is a mirror? It’s the color of whatever it’s reflecting. Silver and similar metals behave the same way; they have no intrinsic color of their own, but they reflect the color of the light that hits them. Recall that the color of objects begins with the light that is NOT absorbed by the surface material; a red object is red because when it is hit by a wide spectrum of light frequencies (such as real or simulated daylight), it absorbs most of the visible wavelengths and leaves only red light to reflect to the viewer. Silver (and most metals) absorb almost no light, reflecting virtually all light they are hit with.
When metal does have color, it’s because it has something on its surface that absorbs certain wavelengths. Tarnished metal has a distinctive appearance that is a popular subject in still-life paintings. Tarnish on silver is generally the result of chemical interaction between the metal and a sulfide in the surrounding atmosphere, such as sulfur dioxide, which can result from various industries as well as natural processes such as volcanoes.
Sulfide-based tarnish, such as what is commonly seen on old silver, is yellow in hue at the outset. As we will see below, when it is more developed, it can “spot” to a dark purple and become almost back in more advanced stages.
In our example below, we can see that the base color of the tarnish on this teaset is approximately 2.5Y 4/2. This is a yellow that is very slightly orange, rather than slightly green. (You may recall that this is also the color of the spathe from the daffodil!) 2 is the maximum chroma we will see in this type of object when considering just the tarnish, although of course it may still be reflecting much higher chromas from other light sources and objects below the tarnish level.
Here, we can see that a darker area of tarnish on the inside of the cup is even darker than our sample chip, which is N 2/. Notice that the hue (or absence thereof) on the N 2/ chip makes it look slightly bluer than the surrounding metal; to suggest the yellow color of the tarnish, if you wish, you can mix in a very small amount of 2.5Y or 5Y 2/2 to give it just a slight blush of hue and chroma.
The tarnished character of the metal can be suggested by judicious application of a high-value, low-chroma yellow for the points between the pure-white highlights and the visibly yellow tarnish. At the highlight points, as below, we can see that the brightness of the metal near the chip is far brighter than the highest-value chip in the Munsell set: N 9.5/. At value 9.5, which is as close as we can presently get to “pure” white at value 10, we have no visible hue.
To help make the bridge between the pure white of the highlight, and the nearly-white of the less-intense highlights in the more tarnished area, you can use a color such as 2.5Y 9/2, in very tiny amounts. This gives an elegant transition through to white and preserves one of the signature characteristics of tarnished metal: the “gleam” of color visible at the edges in bright areas that make it clear what the color effects are.