Purchase an automotive or trailer cleaner that best suits your needs. General automotive cleaners work well, except those containing abrasives. If you are unsure about which cleaner to use, talk to your trailer's manufacturer or read reviews online. Purchase a standard automotive wax to seal the painted sides of the trailer.
Clean the inside of the trailer thoroughly with a sturdy broom and vacuum. Remove all debris and dust.
Add three tablespoons of mild soap to a large bucket and fill with water. Clean the inside of the trailer using sponges and use a hose to rinse with clean water. Dry the area thoroughly with dry rags.
Clean the outside of the trailer with automotive cleaner and water. According to the cleaner's directions, add to water and use clean sponges to scrub the exterior. Remove all spots, dirt and discolorations. Clean all areas to remove chemicals from environmental pollution, sand and salt. Rinse the entire trailer with clean water.
Using dry rags, dry the entire trailer thoroughly. Wipe door jams with a damp cloth.
Wax the trailer's exterior by applying wax with a clean cloth. Never apply wax directly to the trailer itself. Wax small areas in sections, making your way around the trailer. Once dried, remove wax with a clean cloth. Use clean cloths throughout this process.
