Hydrochromic ink

Have 3 kinds:Reversible fading ink:white-transparent.
water-based.White in appearacne.Whent its wet by water,white color will disappear,after its dry,it can return to white again.
Irreversible Diffusion:Water-based.Color at appearance
When wet by water,it can diffusion,after dry,cannot return to original.
Black diffusion to other color:Solvent based,Black at surface,when its wet by water,it can diffusion to other color,after its dry,can not return to original.