Phone screens sense touch by measuring a change in a tiny electric field at the surface. A fingertip is conductive enough to disturb that field in a small, well-defined spot, and the phone reads the middle of that spot as your touch point. It is a precise system, and it is easily confused.
What sweat actually does
A thin film of moisture is also conductive, which means the screen no longer sees one small disturbance — it sees a large vague one that moves and changes shape as the film spreads. The result is not a dead screen but an imprecise one: swaps that start in the wrong place, taps registered a piece to the left, and drags that stop halfway.
This is exactly the failure mode people describe as "the game keeps missing my moves" during a long session, and it is why it happens on hot days and never in air conditioning.
Sunscreen is worse than sweat
Sunscreen leaves an insulating oily layer on both your finger and the glass. It reduces the touch signal rather than smearing it, so taps are simply ignored, and it degrades the screen's oleophobic coating over time as you wipe it off. In an Australian summer this is the single most common cause of a phone that has apparently become unresponsive.
Things that help, in order
- Dry both surfaces. Finger first, then screen, with a dry microfibre cloth. Not a shirt.
- Get out of direct sun. Above roughly 35 degrees, many phones also start thermal throttling, which adds real lag on top of the touch problem.
- Check the screen protector. A thick or badly bonded protector, especially one with trapped air at the edges, reduces sensitivity in exactly the corners of the board a puzzle game uses.
- Turn on high touch sensitivity, if your phone has it. Several Android models and recent iPhones with a protector fitted expose this setting.
- Swap hands. The resting hand dries out in a couple of minutes.
Why we ended up making sleeves
Because the drying-your-thumb-on-a-shirt cycle happens every ninety seconds on a bad day, and it is genuinely annoying when you are two moves from finishing a stage. A thin knitted sleeve over the fingertip keeps a stable, dry contact patch between skin and glass, and because the knit contains silver fibre it stays conductive — the screen still sees an ordinary fingertip, just a drier one.
They are not magic. In an air-conditioned room you will not notice any difference at all. On a February afternoon on a balcony in Perth, they are the difference between playing and giving up.
What not to bother with
- Talcum powder. It works for ten minutes and then gets into the speaker grille.
- Gloves marketed for touchscreens. Fine in a cold climate, actively hot here.
- Stylus pens for match-3. The genre is played with broad, fast gestures; a fine tip makes it slower, not more accurate.
The sleeves are $11.99 AUD for six, posted from Perth, quoted by email before anything is paid.