Kashering Plates and Bowls

Plates are the clearest illustration of a principle that governs all of kashering: a vessel is purged the way it absorbed. Get the level wrong and nothing has happened.

Metal plates and bowls

Where cooked food is poured into them straight from the pot, they absorbed at that level — so they are kashered by pouring boiling water from a kli rishon.

And the converse is stated explicitly: if the water was poured from a kli sheini, they are not kashered. The effort was made and the job was not done.

But if the plates are only ever used at the kli sheini level — food transferred onto them from a second vessel rather than from the pot — then kashering at that same level does work.

So the question is not "what is the strongest method I can manage" but "what level did this actually absorb at". Matching it is what counts.

Porcelain and china

These have the status of earthenware, and earthenware has no kashering. It cannot be done.

This is the one place in a dinner service where the answer is simply no, and it is why households keeping separate sets generally treat china as permanently assigned rather than convertible.

Glass

Glass plates and glassware are a genuine dispute rather than a settled rule, and glass used on the fire — Pyrex and similar — is harder again. That has its own treatment: see can glass be kashered.

Plastic and melamine

Plastics sit within the broader question of whether materials not named in the Torah can be kashered at all, on which authorities differ. In practice much plastic tableware is treated as not kasherable, and items likely to be damaged by the process are excluded on that ground too.

The useful summary

Before any of it, leave the vessels unused for a day and clean them to the required standard. What your own dishes need is a question for your rav.