Vacuum metallizing

That shiny "chrome" plating on some Transformers toys is not applied by traditional electrical or dip plating, but by vacuum metalizing.

In this process, the part is placed in a chamber with most of the air pumped out. Metal vapor enters the chamber and condenses on the part to form a very thin and shiny metallic coating.

The most common metal used for this process is nearly-pure aluminum, which gives a "silvery" finish. To change its color to gold, red, or whatever is desired, a transparent, colored paint may be applied over the metalizing. A clear coat may be applied even if the metal's natural color is suitable, to protect the finish.

This metal coating, if made of a corrosion-prone metal like aluminum, may easily tarnish and grow dull if its protection wears off. Furthermore, it is very thin, and may flake, peel, or be worn away with prolonged play. When new, though, it looks totally rockin' cool awesome and rad.

Toys produced and sold in recent years have used few or no plated parts, and the metalizing was omitted from toys in the Universe line which had originally featured it, such as the Transmetals.