Your wiper blades are responsible for clearing a viewable path on your windshield so you can see where you’re going. They wipe away rain, snow, ice, dust, dirt, bird droppings, and any other debris that ends up on the windshield.
When your windshield is dirty, sometimes the best way to clean it is to spray washer fluid (if it’s already wet out you can forego the washer fluid) and engage the windshield wipers. The washer fluid begins to dissolve whatever is on your windshield, but it also serves as a lubricant for the glass. Larger particles of sand, dust, and mud are often smeared around on the glass in the process of cleaning, causing tiny scratches in your windshield. Washer fluid can act as a buffer between the glass and the dirt, preventing some scratches from ever occurring.
Dirt and mud can also ruin wiper blades, especially if it has already dried. The dirt, sand, and stone content in the mud is abrasive and can nick the rubber on your wiper blades or even cause them to tear. A nick or tear in the wiper blade will prevent the rubber edge from making consistent contact with the windshield, leaving streaks when cleaning. This can obscure your vision and make it harder to see. If this happens, you’ll need to replace your wiper blades.