The background of the project is to evaluate the colour changes of wood not only as a function of time. Space-time is the fourth dimension (in addition to the three spatial dimensions). However, time is not the real factor affecting the wood surface, but the electromagnetic radiation from the sun. Light is the visible (VIS) part of the electromagnetic spectrum, in addition to other components such as ultraviolet (UV) and infrared (IR) radiation. UV-, VIS- and IR-radiation have an energetic effect on the wood surface as part of the solar radiation spectrum. What are the effects of the solar radiation spectrum on the wood surface? This is an important question, as the evaluation in terms of irradiation intensity has not been the subject of detailed investigation. Radiation intensities are reported in many studies. However, this information usually has the status of metadata. The concrete influence of irradiance on chemical and colour changes in wood remains open. There are also other questions: Is there a difference between summer and winter irradiation? Is there a difference between natural (sunlight) and artificial (laboratory lamps) irradiation? Is there a difference between direct and indirect irradiation? We measure the irradiance on the surface of the samples with a device called pyranometer. Irradiance is the term for the total power of incoming electromagnetic energy striking a surface, related to the size of the area, measured in watts per square metre [W/m²].
Why am I doing this kind of science? I asked myself the question: Why are the colour changes of wood always shown as a function of time? When people lie on the beach on holiday, is it time that makes their skin turn brown (or red, in the worst case)? People put sunscreen on their skin, but it does not protect them from space-time, it protects them from the sun’s rays. Sunscreens have a specific sun protection factor (SPF). SPF is a measure of the amount of solar energy required to cause a sunburn on protected skin (i.e. in the presence of sunscreen) relative to the amount of solar energy required to cause a sunburn on unprotected skin. Sun creams delay sunburn, but cannot prevent it permanently. Isn’t it the same with wood, except that you do not put sun cream on wood? Wouldn’t it make more sense to show the colour changes of wood as a function of the irradiation dose? Therefore, curiosity is my driving force.
Keywords: time, irradiation, wood, indoors, scans, colour changes, radiation dose
Authors
Claudia Lenz
Eberswalde University for Sustainable Development, Faculty of Wood Engineering, Eberswalde, Germany
Paul Gollee
Eberswalde University for Sustainable Development, Faculty of Wood Engineering, Eberswalde, Germany
Alexander Pfriem
Eberswalde University for Sustainable Development, Faculty of Wood Engineering, Eberswalde, Germany
Login to download the PDF