Now there is a newly developed ink called osmotic ink.

After two or three days, this ink will slightly penetrate into the PE plastic bag, so that it has strong adhesion and will not be erased (PE film requires high adhesion to ink. )

As far as I know, there are several dairy manufacturers using this ink at present, so I think this should be no problem.

As for "blooming", it may be that the adhesion of ink is not the best, and it is sterilized by high temperature cooking (the ink turns from black to blue after high temperature). ), resulting in "halo" phenomenon.

Attached Figure: The proofing effect of penetrating ink in a dairy industry.