Anandakanda 1.16.8

1.16.8

tatastu ṭaṅkaṇaṃ tadvat tattadvaktreṣu lepayet /
tatpātraṃ kāṃsyapātre ca sthāpayet tadadhomukham //

Then, one should likewise smear borax onto their respective mouths. / One should place that vessel inside a bronze vessel, turned upside down.