If one uses an electric hotplate to warm meat pots and the like, it is quite common that some of the meat food inside these pots will sometime fall onto the hotplate thus causing the hotplate to absorb this meat flavor. As such, if one then wishes to place dairy foods onto the hotplate, if one does so when the hotplate is completely clean and the dairy food is placed within a vessel in a way that the food will not be in direct contact with the surface of the hotplate, this is completely permissible, for the vessel does not absorb any flavor from the hotplate since we have a rule that one vessel cannot absorb the flavor of another vessel unless there is liquid between them and in our scenario, both the hotplate and the vessel placed on top of it are completely dry. Nevertheless, if one wishes to place a dairy food item, such as a cheese borekas, directly onto the surface of the hotplate without first being placed into another vessel, there is a concern that the borekas will absorb some of the meat flavor from the hotplate and that the hotplate will likewise absorb some of the dairy flavor of the borekas and the hotplate will then have absorptions of both dairy and meat. Thus, one must act stringently and not place dairy foods directly onto the surface of the hotplate. (Nevertheless, the Yalkut Yosef writes that one who places dairy foods directly onto a hotplate which has previously absorbed meat flavor has on whom to rely.)
If one wishes to warm bread on a completely clean meat hotplate and eat this bread with dairy items, this is certainly permissible, for even if the bread were to absorb some meat flavor from the hotplate, it would nevertheless be permissible to eat this bread with milk or cheese since the minute absorption of meat by the bread does not prohibit it from being eaten together with dairy. For the same reason, it is permissible to eat a Pareve food item cooked in a completely clean meat pot (even if it was used for meat within the past twenty-four hours) with dairy once it has been removed from the pot, for the minute amount of meat flavor that is released from the pot to the food is insufficient to render the food “meat” and prohibit its consumption with dairy.
Nevertheless, this that we have written that one may place bread on a hotplate and we need not be concerned about the meat absorptions in the bread and the bread may be eaten with dairy only applies to the laws of milk and meat. However, if one wishes to use a Chametz hotplate to place foods on it during Pesach, the hotplate must first be koshered by pouring boiling water from an electric kettle all over its surface. We have already discussed this law in the context of the laws of Pesach.