Prior work has proposed that hemicellulose acetylation rather than lignin acetylation was the dominant biopolymer influencing diffusion in secondary cell walls. The proposed mechanism for the role of hemicellulose has been hypothesized to be that the hemicellulose and amorphous cellulose are prevented from passing through their moisture-induced glass transition due to acetylation. Experimental acetylation involves exposure to acetic anhydride and the accessibility to the acetic anhydride reagent is significantly greater in lignin compared to hemicellulose, yielding a relatively higher rate of acetylation in lignin. Lower WPG therefore display a greater extent of lignin modification; Rowell et al. estimated that at 8 WPG, approximately 80% of lignin hydroxides had been modified while only 12% of the eventual hemicellulose modification has occurred. In our models, we do not directly account for this differential acetylation, as we are deciding what to acetylate based on water accessibility. Indeed, analysis indicates that our partially acetylated models have approximately equal numbers of acetyl groups on both lignin and hemicellulose. Since hemicellulose has many more hydroxyl groups than lignin does on a per-monomer basis, an equal number of acetyl groups means that more of the available lignin is modified overall.