Well I got my order today, excited to go lift but got uni to go to. Will report back tonight on how the liquid chalk goes. I did try a little bit of the liquid chalk and it leaves like a thin, white, chalky residue on your hands and your hands feel "grippy". The liquid is basically like a hand sanitiser.
I did look up what lifting chalk was made of and its magnesium carbonate, so if the kid chalk was made of magnesium carbonate then I guess it would be the same?