Coating Components in a Vacuum
aerospace coating

The atmosphere is full of contaminants - especially if you are considering coating a metal part with a 5 micron thick metal alloy. Dust will get in the way. For this reason (among others) the quality of the vacuum in which a coating is laid down, is important.

In some cases, when
applying a simple paint to a component the environment is critically important.

Where a partial vacuum is the optimal environment for treatment,
Argon can be the best gasification to use. This inert (albeit highly dangerous gas) allows the coating to take place very efficiently.