What is acetone primarily used for in automotive refinishing?

Acetone is primarily used as a solvent in automotive refinishing for cleaning and thinning purposes. It is effective at dissolving various materials, including oils, greases, and paint residues, making it an ideal choice for preparing surfaces prior to painting. By cleaning surfaces with acetone, technicians ensure that paints and coatings adhere properly, leading to a better finish and increased durability.

Additionally, acetone's ability to thin certain types of paints and coatings allows for better application flow, ensuring an even and smooth coating. Its fast evaporation rate also contributes to quicker drying times, which can be advantageous during the refinishing process.

The other options do not accurately reflect acetone's primary usage. While it may assist in drying processes indirectly due to its quick evaporation, it is not specifically classified as a drying agent. Similarly, it does not function as a primer or a paint hardener, which serve distinct roles in the refinishing process.