Paint operation

Transformers toys are often partly or wholly painted. Die-cast metal must always be painted if a tarnished gray finish is not wanted; plastic parts, commonly molded in color, can also be painted to highlight detail or add visual interest.

These painted areas, or paint applications, on mass-produced Transformers toys, are applied by spraying through a paint mask, in cases where total paint coverage is not wanted.

From Teletraan I: The Transformers Wiki, a Wikia wiki.