Experiment Setup
Tempered glass protectors will outperform both film and liquid nano-coatings in scratch resistance, clarity retention, and oleophobic durability over 30 days of real-world use.
- Three identical Samsung Galaxy S24 units
- Each phone carried in same pocket daily
- No cases — screen-only protection test
- Identical apps and usage patterns
- Scratch count under 10x magnification
- Clarity rating (1-10 scale)
- Oleophobic performance (water drop test)
- Touch responsiveness
- Visual inspection score
- Glass: Spigen GlasTR ($13)
- Film: amFilm TPU ($8)
- Liquid: Liquid Shield Pro ($25)
Day 0 — Starting Baseline
Week 1: The Adjustment Period
Right away, the three phones felt different. The glass protector was barely noticeable — it added about 0.3mm of thickness, but the touch feel was nearly identical to bare glass. The oleophobic coating was excellent. Water beaded up perfectly, and fingerprints wiped clean.
The film protector was a different story. You could feel the edges. There's a slight "tackiness" to TPU film that never fully goes away, and swipe gestures felt marginally less smooth. Not terrible, but noticeable if you're paying attention.
The liquid nano-coating was the most interesting. After application and a 24-hour cure, the screen felt exactly like bare glass — because it essentially is bare glass with a molecular coating. Touch feel was a perfect 10/10. No edges, no thickness, nothing to see.
Daily Carry Conditions
All three phones went in my front right pocket daily — no case, screen facing my leg. Keys, coins, and pocket sand were the enemies. I also tested placing them screen-down on various surfaces: wood desks, granite counters, and metal turnstiles.
Glass was untouched. Film showed its first vulnerability. Liquid was already accumulating micro-scratches at an alarming rate — roughly one per day of normal carry.
Week 2: The Separation Begins
By the second week, the gap between protector types was becoming undeniable. I started each morning with a scratch inspection under a 10x loupe, and the patterns were clear.
The glass protector still showed zero scratches. I deliberately ran a key across it with moderate pressure — nothing. The oleophobic coating was holding strong, though I noticed it was slightly less aggressive than Day 1. Water still beaded well, but the beads were marginally larger.
The film protector picked up three more fine scratches, bringing the total to five. Two of them were deep enough to feel with a fingernail. The self-healing property worked on the shallowest scratches over 24-48 hours, but anything deeper was permanent.
The liquid nano-coating was in trouble. A total of 10 micro-scratches were now visible under magnification, and three were visible to the naked eye in direct sunlight. The oleophobic effect had degraded noticeably — fingerprints were smearing instead of beading. Touch feel was still good because there's nothing on the screen to feel, but the visual deterioration was significant.
The glass protector was living up to its promise. Film was performing as expected — sacrificial but replaceable. Liquid was failing in the one area that matters most: scratch protection.
Want the Full Tracking Spreadsheet?
I'll send you the exact spreadsheet I used — scratch counts, clarity scores, and daily notes for all 30 days.
Check your inbox — spreadsheet is on the way.
Join 2,400+ readers · No spam · Unsubscribe anytime
Week 3: Stress Testing
Week 3 was intentional punishment. I dropped each phone from waist height onto concrete (screen-down) once, carried them with keys in the same pocket for three days, and placed them screen-down on rough surfaces daily.
The glass protector took its first real hit. The concrete drop produced a small chip in the upper right corner — about 2mm across. Two hairline scratches appeared, visible only under direct light. The rest of the surface remained pristine. Critically, the actual phone screen beneath was completely untouched. The protector did exactly what it was designed to do: sacrifice itself to save the screen.
The film protector now had 8 total scratches, with three clearly visible without magnification. The oleophobic coating was at roughly 50% — fingerprints were sticking, and the screen needed cleaning twice daily instead of once. The edges were starting to lift slightly from pocket friction.
The liquid coating was essentially non-functional as a protective layer. 18 scratches total, with seven visible to the naked eye. The oleophobic effect was nearly gone. The screen felt rough and grippy — the opposite of what you want. I was essentially looking at a scratched phone screen with extra steps.
Glass took a concrete drop and sacrificed a corner chip to protect the screen beneath — exactly its job. Film was degrading on schedule. Liquid had effectively ceased to function as a screen protector.
Week 4: The Final Count
The last week was about endurance. No additional stress tests — just normal daily use to see how each protector held up under routine conditions.
The glass protector added two more hairline scratches (likely from the chip exposing edges), bringing the total to 3 scratches and 1 chip. The oleophobic coating had degraded to about 65% effectiveness. Touch responsiveness remained perfect throughout the entire experiment. The screen underneath? Completely flawless when I removed the protector on Day 30.
The film protector ended with 14 scratches, six of which were visible without magnification. The self-healing property worked on only the shallowest marks. The oleophobic coating was at maybe 30% — the screen looked perpetually smudged. But it had still absorbed damage that would have hit the screen.
The liquid nano-coating finished with 27 scratches. Under magnification, the screen looked like it had been cleaned with sandpaper. The "protection" was purely theoretical at this point. When I compared it to a control phone with no protector at all, the results were nearly identical — which tells you everything about liquid coatings.
After 30 days, the data is unambiguous: tempered glass is the only screen protector that actually protects. Film is a budget compromise. Liquid is marketing.
Results Summary
30 days of real-world testing across three identical phones. Here's the final scoreboard.
Scratch Accumulation Over 30 Days
Verdict
After 30 days, three identical phones, and meticulous daily tracking, the answer is unambiguous: tempered glass screen protectors are the only type that actually works. They're not perfect — they chip, they scratch eventually, and the oleophobic coating degrades. But they do the one thing a screen protector must do: take the damage so your screen doesn't.
The film protector is a budget compromise. At $8, it's cheap enough to replace every few months, and it will absorb scratches that would otherwise hit your screen. But the visual degradation is real, the touch feel is worse, and you'll be replacing it regularly. If you're rough on phones and don't want to spend $13 on glass, film is acceptable. Barely.
The liquid nano-coating is, bluntly, a scam. At $25, it's the most expensive option and the worst performer by every measurable metric. It accumulated 27 scratches in 30 days — nine times more than glass. It's a $25 bottle of marketing. I cannot recommend it under any circumstance.
Final Recommendation
Buy a tempered glass protector. Spend $10-15 on a reputable brand. Replace it when it chips or the oleophobic coating wears out. Skip film unless budget is your absolute top priority. Skip liquid entirely — you'd be better off with nothing.