Aging of wood: Analysis of color changes during natural aging and heat treatment

The color properties of aging wood samples from historical buildings have been compared with those of recent wood samples that were heat treated at temperatures ranging from 90 degrees C to 180 degrees C. The results of kinetic analysis obtained by the time-temperature superposition method showed that the color change during natural aging was mainly due to a slow and mild oxidation process. In other words, heat treatment could accelerate the changes in wood color that occur during aging. In one sample, the color change (Delta E-ab*) after 921 years at ambient temperature was almost equivalent to that of heating (artificial aging) approximately for 6.7 h at 180 degrees C. The results have been interpreted that the aging and the subsequent change in wood color begin at the time of tree harvesting.