Dyeing of solid wood using scCO(2) as transport medium does not afford satisfying results as exemplarily demonstrated for disperse blue 134 and different wood species. Surprisingly, the bark of cork oak featuring closed porous architecture could be easily dyed with DB 134 which was hypothesized to be caused by the high content of lipophilic moieties in the suberin-rich thin walls separating the individual cells. To verify that non-polar constituents and their plasticization play a key role for diffusion of dye-loaded CO2, we impregnated wood samples with lipophilic alkyl ketene dimer (AKD) and confirmed its presence in the interior by FT-IR and water contact angle measurements. The results of subsequent scCO(2)-assisted dyeing confirmed that deposition of the common paper-sizing agent AKD on the internal surface of the wood samples significantly improved dyeing with DB 134 as evident from CIELAB colour space measurements.