The Blending Mode slider controls the strength (i.e. opacity) of the color or pattern.
You can set values from 0% to 100%. A value of 100% will apply the color or pattern at full strength.
If Texture Paint is enabled, the texture will be applied in the ratio of 1:1. The lower you set the strength value, the more transparent the color or pattern will be. The drop-down list on the right defines the blending mode itself. These modes, such as Darken and Multiply, work in just the same way as they do in most 2D paint programs.
The following terms are used below to help describe the effect of the blending modes:
The various blend modes are explained here. The following mode is specific to the color manager:
This mode erases pixels in the active layer — the erased areas become transparent and the layer underneath shows through.