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This science fair project was conducted to evaluate the water repelling properties of glass coatings used on a car's windshield. Tests were done to compare between two brands of repellent - Rain-X and Aquapel.


Car windscreens with Rain-X are able to repel water better.

Scientific Terms

Microscope, contamination, water repellent


Glass and water repellents

Glass is a very special material but when it is viewed under a microscope, plenty imperfections may be observed. The surface actually contains many pores which can easily trap contaminants, dirt and moisture.

Rain water mixes with brake dust, oil spills, rubber particles released from tyres and other types of dirt found on roads. When we drive along a road on rainy days, a lot of this dirt and contaminated water is splashed on to our windshields. Moreover, when you use your wipers, whilst water gets pushed off the glass, a heavy pressure is applied in the windshield by the wiper blades, causing dirt found on the glass to be forced into tiny surface pores.

The best solution for the problem is to coat the windshield with a water repellent material, which will also help to fill up these pores. The windshield then possesses water-repelling properties and any water on the surface will be seen to form into a “bead” shape. These droplets are easily blown off the windscreen, as the car moves forward at high speeds.

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Complexity level:
Project cost ($):
Time required:
1 hour to prepare, 1 hour for the science project experiment
Material availability:
Easily found
Safety concerns:

Handle glass carefully - wear protective gloves