All different types of Hagala follow one single principle: Kebol'o Kakh Polto, which means that the expulsion of any substance of Chametz absorbed in the walls of a utensil, will occur in the same way that those particles were absorbed there in the first place. The process of Hagala is different for each type of utensil, depending on the material from which it is made, and the way we use it.
Some examples of Hagala
Glass: According to the Sephardic Minhag, any clear-glass utensils like cups or even plates used throughout the year for Chametz should be thoroughly washed and they can then be used for Pesach without any further Hagala.
Metal: All tableware like forks, spoons or knives should be thoroughly cleaned and then immersed in a pot of boiling water. Then, they are washed with cold water and can be used for Pesach.
Porcelain: Ceramic, pottery or porcelain china and tableware that are used throughout the year for Chametz are not suitable for Pesach. In other words Hagala does not sterilize them; therefore they cannot be used for Pesach. (There are some exceptional cases in which they might be used. Ask a Rabbi for details).
Awesome Pesach video!!! http://www.youtube.com/watch?v=BIxToZmJwdI
Rabbi Yosef Bitton. YMJC | 130 Steamboat Rd. | Great Neck | NY | 11024