From: Rabbi Akiva Eiger
To: Unknown recipient
Rabbi Akiva Eiger, in a marginal gloss, challenges the Shach's ruling that one should wait twenty-four hours before using a prohibited vessel mixed with others, arguing that both eino ben yomo and hagalah ultimately operate through bitul rather than independent permission, and therefore the vessel should not be classified as davar sheyesh lo matirin at all. He concludes with tzarich iyun, leaving the difficulty unresolved.
Source: Shu"t Rabbi Akiva Eiger §27