How to clean a screen safely

A clean screen is the first step of any screen test — dust and smudges are easy to mistake for dead pixels. Here's how to clean without damaging coatings.

What you need

A clean, dry microfiber cloth.
A little distilled water for stubborn marks (tap water can leave mineral spots).

Your manufacturer's cleaning instructions always come first. The steps below are general advice for when you don't have them.

Step by step

Turn the screen off and let it cool. Smudges are easier to see on a dark screen, and it's safer.
Wipe gently with the dry cloth in one direction to remove dust.
For fingerprints, put a little liquid on the cloth, not on the device — never spray liquid directly on the screen, as it can seep into the edges.
Wipe without pressing hard, then dry with a dry part of the cloth.

What to avoid

Paper towels and tissues: they can scratch coatings and leave fibers.
Harsh cleaners such as ammonia, bleach and window cleaners, especially on matte anti-glare monitors.
Pressing on LCD panels: it can cause pressure marks or damage.

What about disinfecting?

Many phone makers allow gentle wipes with isopropyl alcohol wipes on glass phone screens, but rules differ between devices and coatings. Check your manufacturer's cleaning guidance first, especially for monitors and TVs.

Then test

Once the screen is clean, run the color test. If a dot moves when you wipe, it was dust; if it stays in place on every color, it's a pixel issue — see the dead pixel guide.