Developing a Test Method to Evaluate the Blackout Effect of Uncoated Curtains at Varying Angles

Abstract: This study aimed to explore the integration of varying angles in small-scale measurements and assess the light transmission performance of uncoated curtains. A total of four curtains were evaluated: blackout curtain samples 1 and 2 had a weft satin structure, while daytime curtain samples 3 and 4 consisted of a twill structure. The primary challenge was the inadequacy of a standardized test method for measuring the blackout effect, which led to inefficiencies and resource consumption for Company X. To address this, the study emphasized the need to investigate and establish a reliable and efficient evaluation method for uncoated curtains. By developing a standardized test method, it is possible to reduce waste material, labor costs, and resource consumption, enabling companies to operate more efficiently, sustainably, and responsibly. In the pursuit of understanding the blackout effect and evaluating the structural parameters of uncoated curtains, this study explored various test methods and parameters. More specifically, parameters such as air permeability, porosity, and thickness together with microscopic evaluation, were investigated to shed light on their influence on light transmission. The voids in the fabric were found to be a significant factor, along with porosity and air permeability, which demonstrated a correlation with lower values for the blackout curtains. The construction of the test method in a small-scale required a controlled space in the form of a lightbox. Light proofing of the box was required and successfully achieved in Prototype 1 using plywood, sealing strips, and fixtures, resulting in a lower lux value compared with the previous internal method. Objective measurements using the Konica CL-500A lux meter provided a repeatable and reliable test method with a lower tolerance value of 0,05 lx. The developed test method, theoretical Prototype 2, incorporates different sun angles by adjusting the curtain’s position, in the angles of 0°, 15°, 30°, 45° and 60°, and the rotation of the sample within 0° to 360° in intervals of 45°. The important parameters of weft density and the subsequent increase in weight were key factors in the results of light transmission, air permeability, and porosity. Furthermore, properties of the uncoated curtains such of continuous filaments and darker color showed a higher blackout effect. After the identification of complications with the lamp used in the measurement, there has been a focus on discussing the significance of a light diffuser. Additionally, alternative approaches to measure light transmission have been presented, such as digital image analysis and air permeability.