The chemical makeup of Rain-X means it takes special steps to remove it. Rain-X is a brand name for an automobile product that repels water from glass. It leaves an invisible waterproofing that survives weather and washing for several weeks. In a moving vehicle during a rainstorm, Rain-X aids windshield wipers by making rain blow off the glass in a curtain, rather than dripping down the surface. But old or improperly applied Rain-X can become smeary and obscure vision in sunshine.
Prepare your windshield. Dust off, then wipe down your windshield with a wet lint-free rag and a mild detergent such as dishwashing liquid.
Apply a slightly abrasive cleanser to a wet sponge. Use a cleanser that does not scratch surfaces -- most will state on the label if they don’t. Rain-X contains a silicon bonding agent, which is why it can repel water so smoothly. Soap and water won’t break it, so be sure your cleanser has some scrubbing power.
Scrub a small test area on a far corner of your windshield. Remember that the cleanser should go on your sponge and not right on the windshield. Use a gentle circular motion. Check for scratches. If there are none, your cleanser has the right amount of abrasion.
Scrub down your whole windshield as long as the cleanser seems safe. Keep your sponge and cleanser very wet to avoid scratching.
Rinse your windshield with fresh cold water.
