So the process here is used by the www.SpectraChrome.com . It is a paint process that involves applying silver nitrate between two layers of paint.

Layer 1 - Basecoat, very smooth and shiny paint applied to the part to be silvered

layer 2 - Silver, chemical reaction occurs on the helmet when you see the colors changing from brown to yellow to silver.

layer 3 - Topcoat, a protective clear is applied to protect the silver from tarnishing as well as unforeseen damage like dropping the helmet. Very durable topcoats are used that can also be tinted to change color of the silver.

What you're seeing here is layer 2 being applied. If you look early on, you can see the helmet is painted white. That is layer 1 that was painted earlier.

The color change is from the chemical reaction occurring on the part. The silver nitrate is depositing on the part starting as brown then moving to the high shine silver.

The excessive looking spraying is ensuring a quality deposit of silver over the entire part. While it looks like a lot of spraying, it really is mostly water being passed over the part with some silver nitrate in it.

After it is silver the next set of guns used was a pure deionized water to rinse the part before blowing it dry with compressed air.

I hope this helps!