From Longman Dictionary of Contemporary Englishink something ↔ in phrasal verbAVto complete something done in pencil by drawing over it in ink → ink→ See Verb table
Examples from the Corpus
ink in• It is filled with newspaper clippings of championships, trophies and pictures of a younger Impastato, hair as black as ink.• On other types of paper marker ink sinks in and may create marks with a slightly fused and feathery edge.• For a somewhat analogous situation, think of a small drop of ink placed in a large container of water.• Restrictions on the use of paper and printing ink resulted in canned goods carrying only half-labels.• An on-screen gauge shows how much ink is left in each cartridge.• I scribbled over the name in ink twenty times in my pocket address-book.• Include the ink sacks in the cooking.• There being no ink left in the pen, Pooley had pierced the points of his speculation through with defunct matchsticks. 