You put it on. You still came home with a warm face and a strip of pink along your nose.

It is almost never the bottle. It is the amount.

The number nobody prints on the tube

An SPF rating is measured in a laboratory at two milligrams of sunscreen per square centimetre of skin. That is a thick, generous, visible layer.

Most people apply somewhere between a quarter and a half of it. Protection does not fall off politely in step with that. A thin coat of SPF 50 does not behave like SPF 25.

So the single most useful change you can make is not a better sunscreen. It is more of the one you own.

How much, in something you can measure

Squeeze sunscreen along the full length of your index and middle fingers. That is roughly a face and a neck.

It is a rough guide, not a law. A larger face needs more. If the layer disappears the instant you touch it, you used too little.

You are aiming for a coat that sits on the skin for a moment before it settles. It should feel like something.

Why this matters more here

South Africa sits under some of the highest ultraviolet readings measured anywhere. A summer afternoon in Gauteng or the Northern Cape regularly reaches an index of 11 or more, which is the top of the published scale.

Altitude adds to it. Johannesburg and Pretoria sit well above 1,300 metres, and there is less atmosphere overhead to absorb what arrives.

None of that requires a beach. A school run, a taxi rank, twenty minutes on a balcony with a cup of coffee. It adds up in a way a single burn never does.

Reapplying, honestly

  • Outdoors: every two hours, and again after swimming or sweating.
  • Indoors, away from a window: once in the morning is genuinely enough. You do not need to reapply at your desk.
  • Indoors, beside a window: glass stops most of the burning wavelengths and very little of the ageing ones. If you sit in the sun at work, treat it as outdoors.

If sunscreen goes grey on your skin

This is a real problem and not a small one. Mineral filters sit on top of the skin as a white film, and on deeper skin tones that reads as ash.

Two ways around it. A chemical or hybrid filter, which absorbs rather than sits. Or a tinted mineral one, where iron oxides carry a colour rather than a chalk.

Tinted formulas have a second advantage. Iron oxides block visible light, and visible light is one of the things that drives pigmentation on deeper skin.

Deeper skin burns less and marks more. If dark spots are your concern, sunscreen is not the optional step. It is the step doing most of the work.

What sunscreen will not do

It will not lift a mark you already have. It stops the next one, and it stops the one you are treating from coming straight back.

That is why every brightening routine we sell says the same thing. Without sunscreen in the morning, you are lifting pigment at night and putting it back by lunchtime.

One thing worth a doctor

A mole that changes shape, colour or size, or one that itches or bleeds, is a dermatologist's job and not a skincare one. Go early. It is a five-minute appointment.