Optical Properties of Wood: Measurement Methods and Result Evaluations (Smart Sensors, Measurement and Instrumentation, 45)

This book describes all optical properties of wooden materials, including definitions and measurement methods of optical parameters such as absorbance, diffuse and specular reflectance, colour and gloss. Basic knowledge regarding the reflectance measurement in the ultraviolet, visible, near- and middle infrared radiation ranges is also discussed. It examines conducting correct optical measurements, as well as introduces the validity limits of the individual methods. Steaming as an environmental-friendly colour modification process is introduced by the description of the steaming properties of eight species. Steaming schedules for wood-working industry are suggested to create optimum colour modification. Natural and artificial aspects of photodegradation are monitored by studying the colour change and using infrared reflectance spectrum measurement. The effect of influencing parameters such as temperature, relative air humidity and leaching effect of rain is also discussed. Combinedeffects of heat and light on the optical properties of wood in all possible combinations are presented. The book helps wood researchers and Ph.D. students perform correct and repeatable optical measurements and evaluations in order to draw the right conclusions. Foreword Preface Acknowledgements Contents Abbreviations 1 Measurement Methods and Characterisation of the Optical Parameters of Wood 1.1 Introduction 1.2 Wood–Photon Interaction 1.3 Reflectance Measurement 1.3.1 Fundaments of Reflectance Measurement 1.3.2 Visible and Ultraviolet (UV) Spectrum of Wood 1.3.3 Near Infrared (NIR) Spectrum of Wood 1.3.4 Analytical (Middle) Infrared (IR) Spectrum of Wood References 2 Measurement and Data Evaluation of Wood Colour and Gloss 2.1 Introduction 2.2 Colour and Its Measurement 2.2.1 Anomalies in the CIE Lab Colour System Regarding to the Colour Determination of Wood 2.3 Gloss and Its Measurement 2.3.1 Regularities Related to the Gloss Parameters of Natural and Treated Wood Surfaces References 3 Applications of Colour Measurement in Wood Research 3.1 Introduction 3.2 Colour Modification by Dry Thermal Treatment 3.3 Steaming as a Colour Modification Process for Wood 3.3.1 Steaming Properties of Black Locust 3.3.2 Steaming Properties of Beech and Turkey Oak 3.3.3 Steaming Properties of Poplar 3.3.4 Steaming Properties of Scots Pine and Spruce 3.3.5 Steaming Properties of Larch and Sugi 3.4 Effect of Wetting and Finishing on Wood Colour References 4 Monitoring of Wood Photodegradation by Colour Measurement 4.1 Introduction 4.2 Outdoor Weathering Test of Wood 4.3 Colour Change of Wood During Photodegradation 4.4 Species Dependence of Colour Change Caused by Photodegradation 4.5 Temperature Dependence of Colour Change During Photodegradation 4.6 Air Humidity Dependence of Colour Change During Photodegradation 4.7 Effect of Water Leaching for Photodegraded Wood 4.8 Photodegradation Properties of Thermally Modified Wood References 5 Applications of IR Spectrum Measurement in Wood Research 5.1 Introduction 5.2 Monitoring the Chemical Changes Caused by Steaming 5.3 Examination of Chemical Changes Generated by Photodegradation 5.3.1 Basic Chemical Changes During Photodegradation 5.3.2 Effect of Temperature 5.3.3 Effect of Air Humidity Content 5.3.4 Effect of Water Leaching 5.3.5 Photodegradation Properties of Steamed Wood. References Index