Kashering glass utensils for Pesach

Hi,

Glass utensils which were used for chametz, but have not been used in twelve months, may be used for Pesach after undergoing milui v'irui (kashering via filling with cold water) three times, across three days. Where that is not possible, one could do hagalah (kashering via boiling water), even by pouring water on them from a vessel that was on the fire. Where there is concern that this could cause the utensils to break, kashering is not needed.

This leniency does not apply to utensils which held grain-based alcohol for extended periods of time.

(Rav Moshe Feinstein, Igrot Moshe Orach Chaim 5:32:1)

Have a  great day,
Mordechai