Problems Cleaning Windscreens

Waimarino Bulletin, Volume 5, Issue 2, 9 June 1987, Page 4 (Supplement)

Problems Cleaning Windscreens

Over the last decade or so, it has become increasingly difficult to clean windscreens. Although it's clean after it's been washed, as soon as it rains it becomes smudged. These smudges don't result from deposits left on the screen by other vehicles' exhaust fumes, but rather by the silicone oil that is a constituent of some car polishes. Because of the presence of this oil in a polish it is unwise to use the same chamois leather or cloth for wiping down the car's bodywork and the windscreen. The most microscopic trace of silicone oil is sufficient to smudge a screen and there is really no satisfactory means of removing the smudge. Ordinary detergents will give temporary relief, but petrol is ineffective. Prevention, as always, is better than cure. To keep a windscreen clean and smudgefree keep a chamois leather exclusively for the purpose and make sure that it is not used for anything else. Smudging occurs through the formation of microscopic drops aided by the water-repellent nature of glass. An effective method of removing silicone from glass has yet to be discovered and even traces which remain at the edges of the windscreen will spread over the entire surface. Moreover, wiper blades are just as vulnerable as the windscreen.

There are a number of preparations for dealing with mist on the inside of the screen, but really the most effective means is to ensure that the car's heating and demisting system is operating efficiently.

Most misting trouble occurs in winter early in the morning, after the car has been standing all night, or in the late evening when it probably has been left parked in a street for a couple of hours or so.