This paper presents a method for estimating normals of mirrors and transparent objects challenging for cameras to recognize. We propose spraying water vapor onto mirror or transparent surfaces to create a diffuse reflective surface. Using an ultrasonic humidifier on a robotic arm, we apply water vapor to the target object's surface, forming a cross-shaped misted area. This creates partially diffuse reflective surfaces, enabling the camera to detect the target object's surface. Adjusting the gripper-mounted camera viewpoint maximizes the extracted misted area's appearance in the image, allowing normal estimation of the target surface. Experiments show the method's effectiveness, with RMSEs of azimuth estimation for mirrors and transparent glass at approximately 4.2 and 5.8 degrees, respectively. Our robot experiments demonstrated that our robotic wiper can perform contact-force-regulated wiping motions to clean a transparent window, akin to human performance.