What do you mean by flat, thick, and celluloid in anime drawing? Can you give a picture?

Painting method - is one of the commonly used fashion painting techniques, easy to learn. It adopts the method of evenly painting each piece of color flat, and the pigment mostly adopts gouache paint or marker with certain coverage.

Thick paint - that is, the use of thick, oily colors for the picture stack, it is the unique coloring method of oil paint.

Celluloid is a material that was used for all single-line, flat-painted animations before the advent of digital technology because the thin sheets made from this material were ideal for animation.