In preparation for Passover, Rabbi Shai Tahan, head of Kollel Sha'are Ezra and head of Beit Erzi HaLebanon, provided practical instructions for immersing the vessels. The Torah commanded us (in Deuteronomy 10:23) to immerse food vessels purchased from the nations of the world in a mikvah of purity in order to expropriate the impurity of the Gentiles that were on the vessel (see 2 Yod 4 beginning of Siman 22).
Even a Teflon pan must be dipped in a blessing since it is made of metal, and even though it is coated with a thin layer of synthetic material, since this material is very thin, it is invalid for the main part of the utensil (the Grish Eliashiv is given in the Book of Kahlah, Kahlah page 95). In contrast, an enamel vessel must be immersed without a blessing. And this is because this metal vessel is coated with glass and earth (Ahl Ya'akov Halk).