On Kashrut

A word about dishes.

The primary criterion for kashrut in serving dishes is the taste, which may be imparted to foods in preparation or to be prepared. That is, where there is the chance that the flavor of trafe could be tasted, the plate and food are forbidden. The principal, notaine ta’am ligam, denotes the sense of taste.

Since cold dishes do not impart the flavor of what was on them previously (unless the dish was not properly cleaned with soap and water, hot enough to scald, or if the plate has a noxious odor due to some lasting effect like rotting milk or rancid meat) cold, raw foods may be eaten on them.  Kosher dishes are always preferred but not required.

In regard to hot foods, the law is more stringent. Hot foods or the heating processes that make them hot will make both the food and dish more susceptible to the dictum of notaine ta’am ligam.  Heating opens pores and allows smell and flavor to seep through. Therefore, hot kosher food must always be served on dishes that are kosher.

Now to the question of what is a kosher dish. Any unused, new dish qualifies as a kosher dish (I have yet to hear of a plate made from pork rinds).  A more critical issue is the process of correcting a wayward plate.  Earthenware, including glazed, and plastics of any kind are impossible to kasher. They can never be used for hot kosher foods. Burying them, scalding them are of no avail. On the other hand, we find glass and metal which are both relatively non-porous and therefore easily kashered. In both instances they may be boiled thoroughly.  Is danger of the glass cracking, it can be thoroughly cleaned and run through the dishwasher, with nothing else at the same time, on the highest cycle.

Where the Halacha is less clear concerns other kinds of materials such as Pyrex and China. Opinions on them differ. And accepted position on the subject is that Pyrex is akin to glass and therefore kasherable.  China maybe thoroughly cleaned and then put away in a closet for a full year. At the end of that time they may be used.

Incidentally, it is not appropriate to use glass dishes for both milk and meat.