This step is important because tap water contains small amounts of ferromagnetic material.  Remove all residual ferrous material from the large glass dishes by cleaning all glass equipment with soap, distilled water, and a lint-free cloth.

Tap Water - water that comes out of your faucet
Ferromagnetic Material - a material that is attracted to a permanent magnet; consists of Iron, Nickel, and/or Cobalt

Proceed to Step 3