I prepped the armor by spray-painting it black. I was unsure how the leaf would cover in the recessed areas, and I wanted them black if they showed. You can skip this if you like, and it may work better with the gray, anyway.
First, a glue is applied. The silver leaf is effectively an extremely thin and fragile foil that comes in small sheets. It can be cut for ease of handling, and multiple layers can be pressed on to cover missed spots - which you generally have to do get into recessed spots. Once the leaf is on, it is still fragile and is best covered with a clear sealer.
There are a variety of brands - some come with the glue and sealer, some have seperate bottles for each.
You simply can't get a smooth textureless surface - it gets all sorts of micro-fine lines that gives it a satin brushed-steel look from any kind of normal viewing distance, and not the glassy polished look of the Lego Pirate chrome breastplate. I stuck the camera up close for these shots so the texture could be seen.
