Demonstrating this importance quantitatively, we can estimate the diffusion length and timescale for penetrating wood treatments, such as ions. For Fickian ion diffusion within in the secondary cell wall, the diffusion length for a given time is estimated by this formula: 𝐿 # = √2𝐷 𝑡. Here, D is the diffusion coefficient and time t is how long one is willing to wait. Over short 50 ns timescales, Cu 2+ has a corresponding diffusion length of less than 1 nm, even at the highest hydration level simulated. A single xylan monomer is about 0.9 nm large. Thus, divalent copper cations tend to remain bound to a single hemicellulose polymer in the cell wall for a considerable duration within our simulation. Similarly, for monovalent sodium and potassium cations, the diffusion lengths are less than 1 nm at below 15% water wt. and between 1 -4 nm at higher levels of hydration in wood. Using these diffusion lengths, we estimate that treatments in dried wood would require timescales on the order of years to permeate 1 inch but may only take a month or two to diffuse within hydrated wood samples. In practice, where the initial concentration gradient is large rather than zero as it is in these simulations, practical treatments would take only hours in water-saturated wood.