And it even has applications in our hobby.
https://journals.openedition.org/ceroart/3950
A couple interesting things there. And most of what was done can be done with less involved equipment.
I figured it should be here, as the same colorants were used in printing inks as well as writing inks. Much of what's there would apply more to autographs than cards.
You may not understand or like it much, but this sort of thing is coming. I don't see that as bad, unless the info is poorly interpreted or used improperly.