Summary of "Can Automotive Coatings Protect Your Smartphone?..."

Can automotive “ceramic” (auto‑grade) coatings protect a smartphone?

What the coatings are

Automotive “ceramic” coatings are liquid siloxane/silica‑based protectants that chemically bond to paint and glass, filling microscopic pores to form a very thin, semi‑permanent smooth layer. Marketing often claims extreme hardness and strong hydrophobicity.

Note: Many products advertise “9H” hardness. This refers to the pencil hardness scale, not the Mohs scale — 9H pencil is roughly equivalent to ~3 on Mohs, so it is far from the hardness of minerals like quartz or diamond.

Test setup

Device and prep

Device: Xiaomi Mi 8 with Corning Gorilla Glass 5 (no screen protector).
Prep: wiped with microfiber and isopropyl alcohol.
Application: coating applied to half the front glass and half the back as a test area, then left to cure (~24 hours in the test; manufacturer guidance recommends longer — see curing below).

Tools/tests used

Water/beading test (drops and tipping to see runoff).
Fingerprint/grease smudge and wipe test (counted wipes needed to remove prints).
Mohs‑style scratch testing using a hardness pick set (JerryRigEverything‑style kit).
Key scuff test and general tactile/visual inspection.
Touchscreen responsiveness check.

Sponsors/tools mentioned: ifixit Mahi driver kit (sponsor), Ting (sponsor).

Key findings

Hydrophobicity / beading: slight improvement in beading and runoff on the coated portion of the front glass. Results were mixed on the curved back. Overall the improvement was modest compared to an uncoated oleophobic screen (many phones already ship with oleophobic coatings).
Fingerprint / cleanability: small improvement. Example from the test: coated screen required roughly ~3 wipes to remove fingerprints vs ~6–8 wipes on the uncoated side. The back showed negligible difference.
Scratch resistance: no meaningful improvement. Under Mohs picks and key scraping, coated and uncoated glass behaved essentially the same; high‑hardness picks still produced deep scratches. The coating did not materially increase the glass’s resistance to scratching.
Durability and abrasion behavior: the coating is extremely thin and adherent — when scratched it didn’t flake or crumble, and it couldn’t be easily peeled off with a fingernail.
Touch performance: no measurable change to touchscreen responsiveness or clarity.

Practical conclusion

Automotive ceramic coatings are not a substitute for a physical screen protector if your primary goal is meaningful scratch resistance. They can, however, slightly improve water beading and make the surface a bit easier to clean. Because a small dose is inexpensive and the coating is long‑lasting on a phone, it may be worthwhile for users who mainly want improved hydrophobicity/cleanability — but expectations should be tempered regarding scratch protection.

Condensed step‑by‑step guide (what they followed)

Clean phone thoroughly with a microfiber cloth and isopropyl alcohol.
Apply a thin, even layer of the ceramic coating to the intended area.
Let cure — manufacturer guidance: allow at least 48 hours initial drying; avoid water for several days (the test waited ~24 hours, but longer is recommended).
Lightly buff off residue with a microfiber towel after curing.
Test/observe: beading, fingerprints/cleanability, and scratch resistance.