- When immersing a utensil, one should see to it that there not be any foreign substance that would act as a barrier (“chatzitza”) between the utensil and the water—such as a price-sticker, or the like, that the owner will eventually remove, or rust that the person does not want)—rather, all such substances must be removed prior to the immersion (Shulchan Aruch, YD, 120:13).
2. However, if the foreign substance is only on a minority of the surface, and the owner is not particular about it—such as a very small patch of rust that he cannot remove and does not care about—then it is not considered a chatzitza-barrier and the utensil may be immersed as is (Chasam Sofer).