What is Joe doing?

In the Chronicles book, there is a well known picture of Joe Johnson detailing the ESB helmet. (He looks rather "deer-in-the-headlights")

It looks like he's holding a sponge or something and working on the cheek area. Does anyone have and idea what he's doing in that pic?

washing , pretty sure of that.

we use sponges at art lessons to rub in the background from a time to time.

I can see how that helmet could be mistaken for the ESB helmet, but it is not.

RS suggested that Joe may be using a scotchbrite pad (or rather something that achieves the same effect as one) to dull down and blend in the paint.

Whet helmet is it then?

It's the preproduction 3 helmet seen in Chronicles

What Chronicles?

Star Wars : Chronicles- amazon link