Pots, dishes and other utensils which were used all year round may not be used on Passover because of the chametz which they have absorbed. This absorbed chametz will be emitted if they are used on Passover. Even though the amount of chametz which is emitted is minute, even the smallest quantity of chametz is forbidden.
If one wishes to make his chametz utensils fit for use on Passover, they must be koshered to remove the chametz that is absorbed within them. How is this done?
One method is scalding; another method consists of making the utensil glowing hot. Some types of utensils, like china, are almost impossible to kasher under normal circumstances.
The laws of koshering are quite complex and the method employed in koshering them depends upon the materials they are made of as well as the manner in which they were used for chametz. It is therefore suggested that a competent halachic authority be consulted so as to determine if and how a specific chametz utensil can be used on Passover.