2, you can use a blank night, and then use an eraser after coloring.

Introduction to Watercolor: Watercolor is a painting method that mixes transparent pigments with water, referred to as watercolor. Because of the transparency of color, one layer of color can cover another layer to produce special effects, but too much mixed color or covering will make the color dirty and the water will dry quickly, so watercolor is not suitable for making large-scale works, but suitable for making fresh and bright small paintings such as landscapes. The color is easy to carry and can also be used as a sketch collection material. Compared with other paintings, watercolor painting pays great attention to expression. Its painting methods are usually divided into "dry painting" and "wet painting".