Boogie's Missus here (currently building myself a Stormtrooper but I'm the one that gets the art jobs on the builds).
Paint is satin black, same as the ESB vocoder. I think he's taken the photo when the paint is still very very wet and under a light so it looks more gloss than satin...
Wasn't happy with the snout so about to repaint, I've remodelled his eyes a bit to get a more level finish and painted the inside of the helmet black (this is what happens when he leaves me to go to the football, I have to fiddle). Looking a lot better now, hoping to get the ears cut out tomorrow.