What happens if dew or rain reaches a freshly applied rain repellent?

Most glass treatments need a period without water while they cure, often the first several hours being the most sensitive. Light dew after the initial hours usually does no harm; the treatment may look slightly hazy until it is fully cured. Do not wipe or wash the glass during the cure time stated on the label. Once it has cured, wipe the glass with a clean, slightly damp microfiber and test it with water. If the glass streaks or beads unevenly, the affected area may need cleaning and a fresh application.