New utensils purchased from a non-Jew must be toveled in a mikvah before being used (Shulchan Aruch Yoreh Deah 120). If so, since we “sold” our chometzdike utensils to a goy over Pesach, should we not have to tovel them before using them again when we buy it back from the goy after Pesach?
Adding some language in the sales contract can help avoid this whole issue. For example, the Chasam Sofer (109) suggested writing in the contract that only the chometz that is “on” the utensils is being sold and not the utensils themselves. With regard to the chometz “inside” the walls of the utensils, since you are not oveir bal yeira’eh on this, it is okay not to sell it as long as these utensils are put away in a hidden place.
The Chazon Ish and the Steipler Gaon were uncomfortable keeping chometz even if there was no issur. They would sell even the chometz inside the walls of the utensils. The Darkei Teshuvah relates that the minhag in his city was to sell the chometz and “lend or rent” the utensils to the goy, thereby avoiding the issue of tevilah.
If the contract stipulated that the utensils themselves were actually sold, there is a machlokes haposkim what to do. Some say that you should tovel both glass and metal utensils without a bracha. Others say that only the metal utensils need to be toveled because their tevilah is Min Hatorah.
The Chochmas Shlomo, Aruch Hashulchan, and Darkei Teshuva hold that this isn’t a real sale for the purpose of tevilah, since both the seller and buyer know that it is not permanent and therefore no tevilah is necessary. (Pischei Teshuvos 448:8)