What's this White Stuff on my Rancilio Silvia?

There are a couple of questions that we get all the time about the Rancilio Silvia:

1. Why does my machine have two water tubes? The manual only shows one.
2. Why is my machine white? I ordered a stainless steel version.

We briefly discuss the answer to question one in this video, but we also covered it here awhile ago. For question two, Gail explains this great mystery in the video below.