Relatives gave our little daughter some stamps (I mean the little plastic things whose front has a protuding (text or image) pattern that can be used to leave the same mark on paper many times) as a gift, together with a little box labeled "Color Box Pigment Ink Option Plate"1.
As we had never heard of these terms, in particular "pigment ink" or "option plate" (neither in English nor of their literal translation to our native language), we assumed it was simply a fancy brand name for what was simply a stamp-pad (which would very much make sense to give along with stamps).
However, upon trying it, it seems like that assumption was wrong - the "pigment ink option plate" appears to dissolve/crumble when a little pressure is applied, parts of it stick to the stamp (thereby making parts of the image the stamp is supposed to leave on the paper blurry or even unrecognizable), and the colour can be smeared over the paper much more easily than what I'm used to from stamp pads.
Trying to find out what "pigment ink" actually is has only led me to inconclusive results, in particular, that it's somehow related to the ink for inkjet printers ...
What is this pigment ink; can it somehow be used with the stamps? Or is it maybe useful for some other kind of crafting little children (child nursery age) can do?
1: It looks basically like this product.