Investigation of Natural Aging by Colour Change in the Historical Wooden Structures of Istanbul

In this study, colour changes were examined in naturally aged wood samples taken from structural elements—such as roof trusses and main load-bearing components—of two significant historical industrial buildings in Istanbul: the Fabrika-ı Hümayun in Zeytinburnu, built in 1846, and structures within the Haliç Shipyard in Beyoğlu, constructed in the 1850s. Samples were selectively obtained from structural elements where biological deterioration was not visibly apparent, ensuring minimal interference from microbial or fungal decay. To identify the botanical origin of the samples, both macroscopic and microscopic wood anatomical assessments were conducted. Thin transverse, radial, and tangential sections were prepared and examined under a stereomicroscope and a polarizing research microscope. The wood was identified as pine spruce and fir species. As a result of the study, the colour parameters L* (lightness/brightness), a* (position on the red-green axis), and b* (position on the yellow-blue axis) were measured in the naturally aged wood samples. In the study, the L*, a*, and b* colour coordinate values of the spruce samples taken from both buildings exhibited variations throughout the aging process, depending on the specific location of the sample within the structure and the architectural element. An increase along the b* axis and a decrease in the a* values were observed. When compared with new wood samples, it was observed that the colour values of the aged wood had decreased. The calculated ΔE (colour difference) values for the aged wood samples indicated significant colour changes by aging effect.