This alone is responsible for a 2x reduction in diffusion coefficient. However, the more significant driver of reduced diffusion is that acetylation displaces interstitial water molecules from within a cell wall, dehydrating the polymer network. The effect of dehydration reduces the diffusion coefficient by a further factor of 5-8x. We also note that cations bind with very long duration to anionic carboxy groups in hemicellulose. Together, these mechanistic insights provide the rational basis for alternative treatments that may lead to longer lasting and renewable building materials, such as by changing the chemistry to make the acetyl groups bulkier and thus displace more water, or to genetically engineer trees themselves to amplify carboxylation in secondary cell walls.