The cause is often the piston converter: the adhesion force of the plastic material is initially very high, so that the ink does not flow sufficiently; after contact with lukewarm water, the converter loosens more easily and the ink flows better. In the shop, testing is on very smooth paper, which makes the writing behaviour appear different than at home on normal paper; therefore, when testing, one's own paper should always be taken along. Nibs cannot be written in — as they write, they always write; with persistent failures, the nib or the writing instrument should be exchanged.