Clean Plexiglas windows using a soft rag or sponge and a gentle cleaning solution. Do not use a scrubbing pad, hard brush or abrasive cleaning powder, as these can scratch Plexiglas easily. Never use any cleaner that contains ammonia, alcohol or any sort of petroleum-based cleaning agent, as these chemicals can actually dissolve the surface of Plexiglas, permanently ruining the window.
Make a gentle cleaning solution by mixing a small amount of either dish soap or laundry detergent with about 1 gallon of warm water. While dedicated window cleaning products are fine for cleaning glass windows, these products contain ammonia and alcohol, which make Plexiglas cloudy and opaque.
Always soak your sponge or cloth in the cleaning solution before starting to clean the window. Even soft cloths or sponges can scratch Plexiglas when dry. For the same reason, only use new or freshly washed rags and sponges when cleaning Plexiglas. Previously used or dirty sponges and cloths can hide small pieces of sand, dirt or other abrasive materials.
If your Plexiglas windows have scratches, remove them using car wax or rubbing compound. Using the applicator that came with the product or a very soft rag, slowly buff the wax or rubbing compound into the scratched area until the scratch is no longer visible. This method works well for scuffs and shallow scratches, while removing deep scratches and dings is much more difficult.