Clear Vision: How to Apply Windscreen Water Repellents That Actually Last

Don't just wash the window. If the rest of the car is dusty, that dust will blow onto your clean glass and ruin the bond. Give the car a good scrub and dry it thoroughly.

Never apply glass coatings in direct Aussie sun. If the glass is hot to the touch, the chemicals will flash (dry) too fast and leave streaks that are a nightmare to get off. Do it in the garage or later in the arvo when things have cooled down.

Use your masking tape to cover the rubber seals and the plastic cowl at the bottom of the windscreen. Some glass polishes and coatings can stain plastics white, and it’s a pain to clean later.

Give the screen a heavy spray of glass cleaner and wipe it down with a clean towel. This gets the loose surface dirt off so you aren't scratching the glass in the next steps.

Use plenty of lubricant (or glass cleaner) and run the clay bar over the entire screen. You'll hear it 'sing' at first as it hits the contamination, then it'll go silent and smooth. This pulls out the industrial fallout and salt that washing misses.

Put a few pea-sized drops of glass polish on an applicator. Work in small circles with a bit of elbow grease. This removes the 'road film', that oily layer that builds up from exhaust fumes and makes your wipers smear. I spent hours once trying to fix a 'faulty' wiper on a mate's Hilux, only to realise it was just 5 years of oily road film. Polished it off and the wipers worked like new.

If you've got bad water spots from bore water or salt spray, use a bit of Grade #0000 steel wool (it MUST be #0000) with glass cleaner to lightly scrub. It won't scratch the glass but it'll eat through mineral deposits. (Don't do this on tinted windows or aftermarket films though!)

Wipe away the polish residue with a clean microfibre. Ensure there's no chalky bits left in the corners.

This is the most important step. Spray Isopropyl Alcohol on a fresh towel and wipe the glass twice. You want the glass to be 'squeaky' clean. This removes any oils from the polish so the sealant can actually stick to the glass.

Apply the treatment (like Gtechniq G1 or Rain-X) to your applicator pad. Work in overlapping circular motions to ensure 100% coverage. I usually do two thin coats on the windscreen for better durability.

Most coatings need to sit for 5-15 minutes until they look slightly hazy. Check the bottle's instructions, as every brand is a bit different.

This can be tough. If the coating is stubborn, use a slightly damp microfibre to break the tension, then follow immediately with a dry waffle-weave towel. Buff until it’s perfectly clear.

Use a torch or your phone light to look at the glass from different angles. If you see any oily-looking streaks, buff them out now before the coating fully cures.