Looking at wood through the skin: A multidisciplinary approach to explore the tactile quality of wood materials

The public defense on 17th April 2020 at 12:00 will be organized via remote technology. Please follow the (Zoom application) link: https://aalto.zoom.us/j/427744149 (Meeting ID: 713 112 352) (For more information about Zoom, please, visit: https://www.aalto.fi/en/services/zoom-quick-guide)This thesis is focused on the developing knowledge base for exploiting the tactile quality of wood materials to improve the user perception of thermal comfort and satisfaction. Through the multidisciplinary approach, sensory, emotional, and thermal perception based on touch sense was studied using various wooden surfaces with various treatment and modification solutions. Psychophysical methods were utilized to collect the perceptual data and various tools were developed for experimentation. Results showed that wood surfaces can elicit emotional component of touch during the tactile exploration of surfaces using finger-tips. Natural surfaces with smooth finishing were perceived positively while coated surfaces that felt a bit sticky-to-touch are evaluated negatively. It seems that preserving the naturalness of wood surface during product development is necessary for retaining the positive emotional component of touch in the wood-products. Perception of topographic attributes of wood surfaces was affected due to the surface treatment methods and modification solutions applied to them. Nevertheless, we still can preserve the naturalness of the surface and promote positive touch experiences, after (sometimes) unavoidable surface treatments or modification solutions, by creating desired sensory attributes of surfaces. The good tactile warmth of wood, in comparison to other building materials, could be exploited to create a thermally comfortable living environment by influencing the perception of the surface temperature to its inhabitants. Results from psychophysical tests showed that subjects can reliably discriminate various natural and modified wood surfaces from each other based on the perception of tactile cold sensation. This is an important reason why we should take into account the thermal properties of wooden surfaces before the application of various treatment and modification solutions. Results offer important insights on how we can improve the tactile warmth of natural wood and other wood-based material surfaces, for example, floorings. The next step taken in the present study was the quantification of temperature perception. The psychophysical parameters were applied to measure the perceptual similarities and differences in the temperature perception between paired surfaces from pine and oak, and pine and ceramic tile. Pine surface at 20 °C, the oak surface at 20.9 °C, and ceramic tile surface kept at 22.66 °C felt equally cold to touch. The discrimination threshold between pine and oak was 2.01 °C, and those between pine and tile was 3.6 °C. The quantification of temperature perception can provide insight to develop a simulation for estimating the increased/decreased use of heating energy in the living spaces due to the use of certain building construction materials. Findings of the present study support the idea that by using more wood in living spaces it may be possible to achieve a thermally comfortable environment at lower room temperature