A clean windshield is very helpful during the rainy weather and aids in visual safety as well. However, it tends to be an overlooked aspect of car cleaning. Many people are concerned about their paintwork and wheels, but forget about the glass on the car.
Initial cleaning and maintaining of your glass is more involved than just wiping it down with soap and water or a standard glass cleaner. Glass can become embedded with dirt and contaminates just like the paintwork. The key to having truly clean glass is in the preparation, similar to how paint needs to be prepped before polishing.
The process of cleaning glass is similar to cleaning paintwork. First, you want to remove the surface dirt with soap and water and then proceed to use a clay bar to remove embedded contaminants. The clay bar will grab the contaminants and pull them from the tiny pores of the glass. Next, you will need to spray a liberal amount of an IPA, or isopropyl alcohol solution. Typically, I will make a 50/50 dilution ratio of 70% isopropyl alcohol and distilled water. This solution will cut through the grease and oils stuck to the glass and usually leave no streaks due to the fast flash time of the alcohol.
The last step will be to buff the glass one last time to make sure no streaks or smudges are missed. Some people like to use a glass cleaner or “shine” as a last step and then do a final buff. However, my preference is to leave a layer of synthetic wax aka sealant on the glass to make it much easier to clean the next time. The sealant when applied to the outside of the glass will also provide excellent hydrophobic qualities when driving in the rain and enhance the safety of your driving.
Once this initial cleaning of the glass is done, it will be much easier to clean the next time and can potentially be cleaned with a simple glass cleaner for maintenance. I like to do a full cleaning about every 6 months just make sure the glass stays contaminant-free and top the glass with a spray sealant after every maintenance wipe down.