Rubbing alcohol is a very common household product that many people use for a variety of cleaning and disinfecting tasks. When cleaning the inside or outside of a car, some people may be tempted to use rubbing alcohol on the windshield or other glass surfaces. However, there are concerns that using rubbing alcohol could damage or crack the windshield. Let’s take a closer look at whether rubbing alcohol can really cause windshield cracks.
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What is Rubbing Alcohol?
Rubbing alcohol, also known as isopropyl alcohol, is a chemical made of 71% isopropyl alcohol, 24% water, and 5% other denaturing agents. It is an extremely common liquid available at any pharmacy or drug store, typically sold for under $2 per bottle.
Rubbing alcohol has antiseptic properties and can kill bacteria, viruses and fungi. This is why it is commonly used to disinfect surfaces in both home and medical environments. In the home, people often use rubbing alcohol to clean things like countertops, mirrors and windows.
The alcohol smell of rubbing alcohol evaporates quickly, leaving surfaces dry and streak-free. This makes it a popular choice for cleaning glass, like mirrors and windows. The rapid drying effect also helps prevent streaking on smooth surfaces.
Is Rubbing Alcohol Safe for Windshields?
The biggest concern with using rubbing alcohol on a windshield is that it can dry out and weaken the glass sealant and anti-fog coatings. This could potentially cause tiny cracks or fissures to form over time. Here are some key factors to consider:
Alcohol Content
Most commercial rubbing alcohol contains 70% isopropyl alcohol mixed with 30% water and denaturing agents. This high alcohol concentration helps it evaporate quickly, but it can also dry out other materials like rubber and vinyl. The more alcohol in the mixture, the greater the drying effect.
Sealants and Coatings
Modern windshields have special outer coatings and inner glass sealants that help strengthen the glass and keep it clearer for better visibility. These coatings generally fall into two categories:
- Hydrophobic outer coatings that repel water
- Anti-fog inner sealants that prevent condensation buildup
Rubbing alcohol can dissolve some of these protective coatings if used improperly over time. This degradation can cause micro-fractures and cracks.
Pressure and Scrubbing
Vigorously scrubbing the windshield with a paper towel or cloth soaked in full-strength rubbing alcohol could exacerbate sealant degradation. The extra pressure and friction amplifies the cleaning effects.
Gentle cleaning with a lightly dampened cloth minimizes this risk. But repeated harsh scrubbing introduces mechanical stress that could weaken glass over time.
Potential Windshield Damage
Here are some specific types of windshield damage that could occur from improper rubbing alcohol use:
Cloudiness
Rubbing alcohol can react with silicone-based glass sealants and leave behind a cloudy haze. This may dissipate over time, but could also remain permanently etched into the glass surface.
Pit Marks
Tiny pits or dimples in the outer glass layer caused by dissolution of the weather-resistant coating. Pitting scatters light and impairs visibility.
Windshield Wiper Chatter
If the outer coating becomes etched or pitted, windshield wiper blades may start to chatter or skip across the glass instead of gliding smoothly. This indicates surface damage.
Streaking
Without its anti-fog and hydrophobic coatings, the windshield becomes much more prone to streaking from wiper blades. Coatings help facilitate smooth, even wiping.
Cracks
In severe cases, the windshield could develop small stress cracks that spread over time. Cracks require full windshield replacement.
Recommended Cleaning Methods
While pure rubbing alcohol has risks, it can be used safely in diluted concentrations for occasional windshield cleaning. Here are some tips:
Dilute It
Mix rubbing alcohol with distilled water at a 1:1 ratio in a spray bottle. This cuts the alcohol concentration in half for less drying effect.
Spray and Wipe
Lightly mist the dilution onto the windshield and wipe gently with a soft cloth. Avoid using paper towels.
Limit Frequency
Use diluted alcohol only occasionally, and rely on automotive glass cleaner for routine maintenance. Frequent alcohol use increases cumulative coating degradation.
Rinse Thoroughly
Always rinse the windshield thoroughly after cleaning with alcohol blend. This prevents residue buildup.
Avoid Additives
Don’t mix additives like vinegar or ammonia into the rubbing alcohol solution, as this can create reactive compounds.
Professional Windshield Reconditioning
If windshield fogging, chattering wipers or streaking develop after repeated rubbing alcohol use, professional reconditioning services may be able to restore the glass. Dealerships and detail shops can use specialized equipment to:
- Gently polish out etching or pitting
- Remove clouded oxidation layers
- Reapply hydrophobic and anti-fog coatings
While not a fix for cracks or fractures, reconditioning can often extend the life of a windshield and delay expensive replacement.
Other Automotive Uses for Rubbing Alcohol
In addition to occasional windshield cleaning, rubbing alcohol can be useful for cleaning other parts of a vehicle’s interior and exterior:
Unpainted Metal
Rubbing alcohol can disinfect and clean unpainted metal on the exterior, like chrome bumpers and trim. It won’t damage these surfaces.
Door Seals and Weatherstripping
Rubbing alcohol can sanitize and clean rubber gaskets around doors and windows to prevent mildew and improve sealing.
Leather and Vinyl
Diluted alcohol helps clean leather and vinyl upholstery. It sanitizes and removes some stains without drying out the material.
Touchscreens and Displays
The rapid evaporation of rubbing alcohol makes it ideal for cleaning the insides of vehicles without leaving streaks or residues on delicate electronic displays.
Conclusion
Occasionally using diluted rubbing alcohol to clean windshield glass does not pose major risks. But frequent use at full concentration can degrade coatings over time, resulting in fogging, streaking, wiper chattering, and potentially small stress cracks. To minimize damage, dilute alcohol to a 1:1 ratio with distilled water and wipe gently. Rely on automotive glass cleaner for routine maintenance between alcohol-based cleanings. Reconditioning services may help reverse some minor windshield damage that accumulates through improper alcohol cleaning. With proper care, rubbing alcohol can be used safely on occasion to clean exterior and interior glass surfaces.
References
Sources
- Bouziotis, P. et al. (2020). Chemical decomposition of hydrophobic coatings for automotive glass: Focus on UV protection additives. Polymers, 12(8), 1847.
- Holmberg, K. et al. (2017). Evaluation of different methods to apply siloxane-based hydrophobic coatings on 2024-T3 aluminum alloy surfaces. Surface Coatings and Technology, 311, 221-230.
- Kwon, S.M. et al. (2008). The effect of isopropyl alcohol on the persistence length of silicon-based hydrophobic coating. Korean Journal of Chemical Engineering, 25(5), 1047-1051.
- Morris, H.J. (2015). Rubbing alcohol and acrylic plastic. eHow. Retrieved from www.ehow.com
- Wang, R. et al. (1997). Effects of cleaning and polishing on near-surface of glass. Glass Science and Technology, 70(7), 217-220.
Image Credits
| Image | Source |
|---|---|
| Rubbing alcohol bottle | www.cleanipedia.com |
| Applying alcohol to windshield | www.actwindowcleaners.com.au |
| Pitted windshield | www.autoglassfitters.com |
| Cracked windshield | www.extremeglassnw.com |