SPF stands for Sun Protection Factor, and it is a time-based number: it indicates how many times longer it takes for the skin to turn red with sunscreen on than without it. If your unprotected skin starts to burn in 10 minutes, with SPF 30 applied correctly, it would take about 30 times longer. But that number only measures protection against UVB rays, the ones that cause burning, and it is only accurate if you apply the amount used for testing, which is quite a bit more than what most people use.
How SPF is measured
In the laboratory, the sunscreen is applied to an area of volunteers' backs in a layer of 2 milligrams per square centimeter and exposed to a lamp that mimics the sun. The amount of radiation required for barely visible redness to appear is measured, both with and without the product. SPF is the result of dividing those two figures.
This leads to two consequences that almost no one knows.
First: SPF does not grow linearly. What matters is how much UVB radiation gets through, and that is 1 divided by the SPF. With SPF 15, about 1 in 15 parts gets through, meaning about 93% is filtered. With SPF 30, about 97% is filtered. With SPF 50, about 98%. Doubling the number does not double the protection: it halves what reaches your skin. That half does matter when the sun is strong every day of the year, like in Colombia.
Second: quantity matters. Those 2 mg/cm² are equivalent, for the face, to a level teaspoon, or two lines the length of your index and middle fingers. Most people apply between half and a quarter of that amount. With less product, the protection drops at least in the same proportion, so an SPF 50 applied at a quarter of the recommended amount may end up protecting like an SPF 15 or less. That is why it is written on our sunscreens: reducing the amount decreases the level of protection.
What SPF does not tell you
SPF refers to UVB rays. UVA rays are something else: they have a longer wavelength, do not cause burning, are barely felt, pass through clouds and window glass, and reach deeper into the skin. They are the ones most involved in dark spots and photoaging, meaning the wrinkles and loss of firmness caused by the sun over the years. A sunscreen can have SPF 50 and provide little protection against UVA rays.
That is why, in addition to the number, you should look for the package to say UVA protection, UVA/UVB, or broad spectrum. It is the half of the job that SPF does not measure. Some packages indicate this with a circle containing the word UVA, or with the PA scale, which ranges from PA+ to PA++++: each plus sign indicates more protection against UVA, and four is the highest level. Our Multi-Protection UV Shield carries both markings.
It also doesn't say how long it lasts. SPF is measured in a single application, at rest. Sweat, water, towels, and rubbing by hands remove it, and some filters degrade with light itself. That is why you should reapply it.
What "50+" means
Above 50, the real differences are small and measurements start to vary from one laboratory to another. That is why regulations allow writing up to 50+ instead of 70 or 100. "50+" means that it tested at 60 or higher; it is the highest category of protection.
In the photo, in the gold tube: Anti-Aging Sunscreen SPF50+.
Why sunscreen is daily in Colombia
Three reasons. We are close to the equator, so the sun is almost vertical all year round and there is no winter of low radiation. Many cities are in the mountains: UV radiation increases with altitude, and in Bogotá, Tunja, or Pasto, there is less atmosphere above to filter it. And the cold is deceiving: temperature depends on infrared, not ultraviolet, so a 14-degree noon in Bogotá can have a very high UV index. Thin clouds allow much of the radiation to pass through.
The UV index provided by weather apps serves as a guide. From 3 upwards, it is advisable to protect yourself; from 8 onwards it is considered very high, and in much of the country that level is reached almost every day at noon.
How to choose yours
Start with the protection: for daily use in Colombia, SPF 50 or 50+ with UVA protection. Then choose by texture, because the best sunscreen is the one you apply every day in the correct amount, and that only happens if you like how it feels.
For combination to oily skin, look for a dry finish. The Anti-Shine Sunscreen SPF50+ is broad-spectrum, has a light texture, and controls shine throughout the day.
If you are concerned about wrinkles or dark spots, the Anti-Aging Sunscreen SPF50+ protects against UVA and UVB with a fluid formula that does not feel sticky.
In the photo: Multi-Protection UV Shield SPF50+.
If you live in the city, the Multi-Protection UV Shield SPF50+ adds protection against pollution. In our clinical study with 20 volunteers, pollution adhering to the skin dropped by 11% after application.
A clarification we are often asked: the Illuminating Emulsion SPF30 has UVA/UVB filters, but it is a day treatment, not a sunscreen. It cares for the skin during daily exposure, and if you are going to be in the sun, you need your sunscreen on top. The same applies to foundations and creams with SPF: they are used in thin layers, far from the 2 mg/cm², and act as reinforcement.
They are all in our suncare section.
How to apply it correctly
It is the last step of your morning routine, after your cream and before makeup. Use the two-finger measurement for your face and don't forget your neck, ears, nape, décolleté, and the backs of your hands, which receive sun every day in the car or while walking.
Reapply every two hours if you are outdoors, and always after swimming, sweating a lot, or towel-drying. If you work indoors, one reapplication at noon is enough, especially if you are near a window, because glass blocks UVB rays but lets a good portion of UVA rays pass through.
Frequently asked questions
What does SPF 50 mean?
That with the sunscreen applied correctly, 2 mg per square centimeter, the skin takes about 50 times longer to redden from UVB rays than without it. In practice, it filters about 98% of UVB. It says nothing about UVA: for that, look for "broad spectrum" or "UVA/UVB" on the package.
Does SPF 100 protect twice as much as SPF 50?
No. An SPF 50 filters about 98% of UVB, and a higher one filters only slightly more. That is why packages only go up to 50+. You get more protection from applying the correct amount and reapplying than by increasing the number.
How much sunscreen should I apply to my face?
A level teaspoon, or two lines the length of your index and middle fingers. With half that amount, real protection drops by at least half.
Does a cream with SPF 30 replace sunscreen?
No. A day cream or emulsion with SPF, like our Illuminating Emulsion SPF30, cares for the skin from daily exposure, but it is not a sunscreen. If you are going to be in the sun, put your sunscreen on top.
If I have dark skin, do I need sunscreen?
Yes. Skin with more melanin burns less, but UVA rays also cause dark spots and photoaging. In fact, dark spots are one of the most common concerns for dark skin tones.
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