1, blue interlining: the front should be bright (protruding) and the back should be slightly gray (sense of space and jumping).

High brightness and gray do not conflict. Adding white to sky blue (or other light blue) will also reduce the purity of blue interlining. This is the drawing of the front cloth. At the back of the picture, in order to open the space, you can mix and match some pink, sunrise red and light green. Look at the picture. Which one do you need? Just coordinating. I don't mind using pink blue or other gray systems directly, it will be monotonous.

2. White interlining: White interlining does not need too much treatment, giving people a clean and clear feeling. A picture with a white interlayer that highlights the object. You just need to brush it flat, and when it's dry, you can sweep two slightly darker dusts, which can also be regarded as folds of projection and interlining.

I'll give you a model painting for your reference. I went to look for it as you asked.

Can consult, hope to adopt, thank you.