Those are nib marks on the Tinker. The nib tines spread apart when you increase the pressure on the pen.
The tines were sharp enough to scratch the surface of the card and that embedded the ink deep inside the paper fibers, like a permanent tattoo. But the ink in the middle of the lines faded and washed away over the years. Probably because the paper was glossy and just didn't absorb the ink. Leaving a traced appearance.