If something is talciest, it has the most talc in it and feels the most like talc.
The word talciest makes people think of softness, smoothness, and maybe baby powder.
Examples:
This baby powder is the talciest of all.
Of all the powders, this one is the talciest.
The talciest blanket is the softest.
The talciest soap makes you feel very clean.
The talciest cloud would be so soft to sit on.
The talciest kitten is the softest and smoothest of all.