Value is the relative lightness or darkness of color and is represented by the achromatic gray scale with black at one end and white the other. Value studies are an integral part in establishing three-dimensional space and volume of an object. Take a look at the image of the three leaves. When you strip away the color you are left with the value. Notice how the different values define the leaves. That is why value studies are so important.
When working with markers, a value is made darker by the continual overlaying of color until the paper is saturated with color at which time the color is at its darkest value. This happens because the ink used in markers is a transparent dye. The result is different when using pigmented inks. To overcome this limitation lighter and darker dye colors are used in the markers. Gray markers emulate the gray scale and are available from 10% gray up to 90% gray in 10% increments as shown in the gray scale created using the Cool Grays. Note that Spectra AD Markers have available 8 degrees of Cool Grays and Warm Grays and 6 degrees of a Basic Grays. The AD Markers have available 10 degrees of Cool Grays, 8 degrees of Warm Grays and 5 degrees of Basic Grays.
There are two ways of working with Gray markers. The first method is to establish values from light to dark. Value is important because it creates volume and space. In painting, artist use this technique called a Grisaille to create a monochromatic gray underpainting on top of which they would use transparent glazes to add color. The same can be done with markers. Essentially, you create a value study and then use colors on top.
The other method is adjusting the value of a colors with the varying degrees of Gray markers. The following demonstrates is using this method with the Spectra AD Markers on Koh-I-Noor Smooth Bristol.
I never could color inside the lines so I thought I would try something different. I outlined the shape of the apple and the stem with Molotow Masking Liquid. Note that some color will bleed under the masking liquid when the area is oversaturated with marker, but it is close to the shape and easily fixed by touching up the area with the appropriate marker colors.
Begin by laying in Canary Yellow (014) following the contour of the apple as shown. You do not need to fill in the whole apple. This will be our lightest value.
Next fill in the entire apple with Peach (064) again following the contour of the apple.
With Poppy Red (019) begin to darken the shadow area.
Next add Red (005) to darken and blend with Poppy Red (019).
Now the moment you been waiting for, we use our Grays to deepen the shadows. Begin with the 70% Cool Gray (029) and gradually darken by blending with 50% Cool Gray (027) the shadows.
Next add Cool Gray 90% (031) to the darkest areas of the shadow along the edge of the apple blending with 70% Cool Gray (029). Use Cool Gray 30% (025) to make any gradations between the red and the shadow areas.
The next step is to remove the masking with a firm vinyl eraser like this nifty Koh-I-Noor Thermoplastic Eraser. Using your finger is not an option because the oil from your skin will eventually yellow the paper. You can see at the bottom of the apple that some marker seeped into the paper under the masking. Simply use the Red (005) and Cool Gray markers to touch up those areas.
For the stem, use Saffron (068), Walnut (047), Dark Brown (002), and blend with Cool Gray 30% (025).
The same 30% Cool Gray can be used to create a shadow under and to the left of the apple.
