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.

Paint limits

There are limitations to what can be painted on a toy. Some plastics used in the Transformers' construction cannot hold paint properly, so they must remain wholly the color they were cast.

Also, the number of paint applications is often given a maximum "do not exceed" number to keep costs within a certain range. And it may take more paint applications to cover a part than at first thought: simply painting the outer surface of a cylinder may take two to four applications, and then another for the ends, if desired.

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