The diffusion of water into additively colored KI was studied at 15 to 45C. The resultant expression for the results was:

D (cm2/s) = 0.58 exp[-6496/T]

It was suggested that diffusion occurred via the interstitial migration of water molecules with, an activation enthalpy of 12.9kcal/mol.

Diffusion of Water in Additively Colored Potassium Iodide Crystals. T.J.Neubert, D.L.Roskelley: Journal of Physics and Chemistry of Solids, 1973, 34[3], 493-500