Use blend modes
You can affect the look of an object by changing the way that it blends with colors underneath it. When you change an object's blend mode, the fill and stroke colors change, depending on what colors occur underneath the object.
To change the blend mode of an object
Select an object.
In the Properties panel, in the Appearances category, click the expand button .
In the Blend Mode list, click an option from the list. See the following for a short description of each blend mode:
Normal The foreground color is fully opaque, except for objects for which the opacity is set to less than 100 percent.
Multiply The Multiply blend mode always creates a darker color (except when the foreground or background color is white, in which case no change occurs). Multiply is like overprinting two inks. For example, setting a yellow box to Multiply and putting the box over a blue area would give you green.
Screen The Screen blend mode (which some other applications call "light") is like projecting two or more colored lights at a white wall. The result is almost always lighter than the original colors. If you position a red path, a green path, and a blue path on top of each other and set them to the Screen blend mode, the result is white.
ColorDodge In Color Dodge mode, the color channels of the background color are brightened based on the color channels in the foreground color. If the foreground color is black, then the mode has no effect. Anything brighter than black dodges ("lightens") the background. The result is often lighter than the Screen blend mode.
Color Burn Here, the background colors are darkened based on the foreground colors. A black foreground color gives you black, and a white foreground color has no effect.
Lighten The Lighten blend mode (which some applications call "brighten") compares the color channels of the foreground and background colors and uses the lighter of the two.
Darken This mode compares the color channels of the foreground and background colors and uses the darker of the two.
Difference In the Difference blend mode, Microsoft Expression Design mathematically subtracts each color channel of the foreground object from the color channel of the background color. If two colors are identical, the result is black. If the two colors are on exactly opposite sides of the color spectrum (such as red and cyan), the result is white. This blend mode produces interesting but sometimes unexpected results, especially with soft-edge paths in bright colors.
Eraser The foreground object acts as an eraser through all objects below it on the same layer. Any object on a different layer underneath shows through.