We have a sort of silicon sponge in Japan we call "German sponge". Quite common here, can be found in just about every household, and very inexpensive. I use it for cleaning mirrors, polishing medals, shining anything nicely. I think if you visit a shop where they sell sponges and scrubbing pads, you can just ask for a silicon sponge. When wet, it polishes glass and just about everything else.