2024-10-03
Your Shirt Is Not a Cleaning Cloth
You do it. I do it. Everyone does it. You breathe on your lens and wipe it with whatever fabric is closest. Your shirt, a paper towel, a tissue, a napkin. And every single time, you are grinding tiny particles into your lens coating and creating micro-scratches that accumulate over time.
Those scratches are why your two-year-old glasses always look slightly hazy even when they are "clean." And why night driving gets progressively worse with the same pair. And why you keep thinking your prescription changed when it has not.
What Actually Scratches Lenses
Modern lenses are not raw glass or plastic. They have multiple thin coatings on the surface: scratch-resistant, anti-reflective, hydrophobic (water-repelling), oleophobic (oil-repelling). These coatings are measured in nanometres. They are tough for their purpose but vulnerable to abrasion.
The problem is not usually the cloth itself. It is the dust and debris already on the lens that gets dragged across the surface when you wipe. A single grain of sand or metal particle on your lens, smeared across with a cotton t-shirt, creates a scratch. Multiply that by hundreds of dry wipes over two years, and you have a lens that looks like it has been through a sandstorm at the microscopic level.
The Common Mistakes
Dry wiping
The biggest one. Wiping a dry, dusty lens with anything, even a proper microfibre cloth, can scratch it. You need to remove the loose debris first. Always rinse before wiping.
Paper towels and tissues
These feel soft but they are made of wood fibres. Under magnification, paper towel is remarkably rough. It will scratch most coatings over time. Tissues are slightly better but still not great, and they leave lint everywhere.
Hot water
Hot water can damage lens coatings. The lens material and the coating layers expand at different rates when heated, which can cause the coating to crack, peel, or develop a cloudy pattern called crazing. Always use lukewarm or cool water.
Window cleaner, vinegar, or household sprays
Windex and similar glass cleaners contain ammonia. Ammonia breaks down AR coating. Vinegar is acidic and can attack coatings too. These products are designed for flat glass that has no optical coatings. Your lenses are not window glass.
Leaving them lens-down
When you set your glasses down on a table, desk, or nightstand with the lenses facing down, every speck of dust on that surface becomes a potential scratch point. Always set them down on the temples (arms) with lenses facing up, or put them in a case.
The Right Way to Clean Your Glasses
This takes about 30 seconds and will keep your lenses in good condition for years:
Step 1: Rinse under lukewarm water
Hold your glasses under the tap and let lukewarm water run over both sides of both lenses for a few seconds. This removes loose dust, sand, and debris. Do not skip this step. This is the most important part.
Step 2: Apply a tiny drop of dish soap
Regular dish soap. Dawn, Palmolive, whatever you have. Put a small drop on each lens and gently rub with your fingertips. Dish soap is formulated to cut grease and oil without abrasives. It is safe for all lens coatings. Avoid soaps with added moisturizers or lotions, which can leave a film.
Step 3: Rinse thoroughly
Rinse all the soap off under lukewarm water. Make sure you get the nose pads and the area where the lens meets the frame, where grime builds up.
Step 4: Shake off excess water
Give them a gentle shake. Do not blow on them (your breath contains moisture and oil).
Step 5: Dry with a clean microfibre cloth
A clean microfibre cloth is key. Microfibre is designed to pick up particles rather than push them around. But the cloth itself needs to be clean. Wash your microfibre cloths regularly (in the washing machine with no fabric softener, which leaves a residue). A dirty microfibre cloth is not much better than a shirt.
What About Lens Cleaning Sprays?
Commercial lens cleaning sprays are fine. They are essentially diluted isopropyl alcohol with surfactants, designed to be safe for coated lenses. They are convenient when you are out and cannot get to a sink. Just spray generously and use a clean microfibre cloth.
The key word is "generously." A light mist is not enough to float debris off the surface. You want the lens wet enough that particles are suspended in liquid before you wipe.
How to Store Them
- Use the case. Not your pocket, not the top of your head, not the car dashboard. The case that came with your glasses exists for a reason. It protects lenses from scratches, pressure, and heat.
- Do not leave them in the car. Canadian summers hit 35 degrees inside a parked car easily. Canadian winters go to minus 30. Both extremes damage lens coatings. Keep them with you or in a case in a bag.
- Take them off with both hands. Pulling them off one-handed by one temple bends the frame asymmetrically over time. You end up with crooked glasses that do not sit on your nose properly and put uneven pressure on the lens edges.
When to Replace vs Clean
If your lenses have visible scratches that show up as lines or smudges that will not wipe away, no amount of cleaning will fix that. Scratches in the coating are permanent. If your AR coating has developed a cloudy, web-like pattern (crazing), that is also permanent coating failure.
At that point, you need new lenses. The good news is you can usually put new lenses in your existing frame if the frame is still in good shape. You do not need to buy everything from scratch.
A Simple Daily Habit
Rinse your glasses when you wash your hands in the morning. It adds 20 seconds to your routine. Your lenses will look better, your vision will be clearer, and your glasses will last significantly longer. It is the cheapest upgrade you can make to your eyewear.