What is put on the line to protect the surface?

To protect a surface, various materials can be applied depending on the context, such as sealants, coatings, or protective films. In construction and maintenance, protective barriers like tarps or plywood may be used. Additionally, in painting or finishing processes, primers and topcoats help safeguard surfaces from wear, moisture, and environmental damage. Ultimately, the choice of protection depends on the specific surface and its intended use.