Shellac material mixes two materials by superimposing one over the other. Colors in the superimposed material, called the "shellac" material, are added to colors in the base material. A Shellac Color Blend parameter controls the amount of color mixing.
Top: Base material
Middle: Shellac material
Bottom: Materials combined with a shellac color blend value of 50%
Controls the amount of color mixing. At 0.0, the Shellac material has no effect. Increasing the Shellac Color Blend value increases the amount of Shellac material color blended into the Base material color. There is no upper limit on this parameter. Large values "overload" the Shellac material colors. Default=0.0.