Students often have difficulties understanding abstract physics concepts, such as solid friction. This study examines high school students' mental models of solid friction through a case study of 215 high school students in the ninth through twelfth grades. An achievement test with three open-ended questions was created, with questions limited to descriptive and visual responses regarding the concept of solid friction. The gathered data were analyzed in terms of rubrics that were used in related literature. By using the rubrics, the various levels of understanding by students were determined separately by the two researchers. The percentage of case agreement between the researchers was calculated as 90% for description and 84% for visualization. The results showed that students mostly think about solid friction at the macroscopic level and have difficulties making sense of it at the microscopic level (i.e., students' mental models are not scientific). In the light of these results, it is recommended that instructors endeavor to explain solid friction at macroscopic, mesoscopic, and microscopic levels.