Linen which has been bleached in Ireland, reputed to have a particularly bright, white finish; (also) the process by which such linen is bleached, in which the cloth is subjected to a cycle of boiling in lye, followed by grassing.
Origin
Mid 18th century.
Definition of Irish bleach in US English:
Irish bleach
noun
rare
Linen which has been bleached in Ireland, reputed to have a particularly bright, white finish; (also) the process by which such linen is bleached, in which the cloth is subjected to a cycle of boiling in lye, followed by grassing.