Use guide

White screen to clean your monitor

Fullscreen pure white makes dust and fingerprints obvious so you can clean a display against a known field.

Steps

Open Instant White on the display you want to inspect.
Tap Open this preset (Clean monitor — full white at 100%).
Enter fullscreen if the browser allows it, so menus and bezels are out of the way.
Wipe with a screen-safe cloth; switch back to white to confirm what remains.

Gray or black fields can show different residue than pure white.
Same field as max white: /?c=white&b=100&f=1&w=1
Power the display off before using any liquid near ports, then reopen white to verify.

A white field reveals soil; it does not clean the panel. Use a cloth meant for screens.
The f=1 query asks the page to enter fullscreen. Browsers typically allow Fullscreen API only after a user gesture (tap or click). The request can be denied, and iOS Safari often ignores programmatic fullscreen.
The w=1 query asks for the Screen Wake Lock API so the display stays on. It requires a visible document, usually HTTPS, and is missing or unreliable in some browsers (notably many iOS Safari versions). The screen can still sleep if the OS, battery saver, or the browser refuses the lock.
Do not spray liquid onto the page or into vents.

Part of Instant White — free fullscreen white screen & solid color light tool.