The pre-treatment was not the decisive factor. The ink was not resistant to the substances in the rust protection agents are usually oils or at least mixtures containing oil. The resistance here also depends on the respective colour. But since the rust inhibitor has a long-term effect on the ink, the more resistant colours are also dissolved + smeared. Unfortunately it is not known which colour was used. If it was not black, this colour should be tried out.moreover, metal is a difficult surface comparable to glass, on which the ink is only on top.since this application is not part of our test scope, we do not have reliable results to offer an alternative. Many inks are oil resistant in the short term, but we cannot say anything about their long-term behaviour.