Sensitive consumable components of printing devices involved in the process of transferring and fixing an image with toner onto a print medium are protected from harmful exposure to the environment and handling through designating and consistently positioning non-use regions of the components toward exposure gaps in their protective housings upon the completion of every printing process. By operating only the throttle lever, both releasing of the brake unit from a braking condition and adjusting the opening degree of the throttle can be achieved. Exemplary anions include, but are not limited to, citrate, phosphate, carbonate, and combinations thereof. Test images, each having a density which is different from the other but constant over the test image, are prepared and an evaluation value is obtained from each of the test images as an evaluation correction value. The amount of any phenate detergent is less than 15% by weight of the total amount of detergents.