Riemann P20 Sun Protection

Sun cream contains filters that prevent UV radiation reaching your skin. There are physical and chemical filters.

Physical filters consist of small particles that help filter out UV radiation.

Chemical filters have molecules that absorb UV radiation and convert it into harmless radiation through a chemical reaction.

Different filters protect differently against UVA and UVB radiation, and a combination of those filters may often be required to achieve adequate protection.

You should apply plenty of sun cream. The most common mistake when it comes to using sun cream is to use too little.

For an adult, about 35 grams of sunscreen should be used, which is equivalent to about 6 teaspoons. Using a smaller amount reduces the protection you receive. If you read the fine print on the packaging, a recommended amount is often stated on the bottle.

The number on sun cream packaging shows what level of SPF the cream has. SPF stands for Sun Protection Factor. According to the European Commission's sun protection recommendation, the minimum SPF you use should be 6.

SPFs between 6-10 count as low protection. Medium protection is offered by SPF 15-25. SPF 30-50 provides high protection, while anything over 50 provides very high protection. SPF 15 lets through 1/15 of the sun's harmful rays, while SPF 30 lets through 1/30 of them.

In percentage terms, this means that SPF 15 provides protection of 93.3%, while SPF 30 provides protection of 96.6%. If you want tips on several good sunscreens, you can read our test of sun creams.

An open bottle of sun cream keeps best in a dark and cool room. In practice, these bottles often accompany you to the beach and are exposed to hot, bright summer days. When exposed to heat, the stability of the sun cream is affected, so it’s important to keep track of the consistency, smell and appearance of your cream.

If it starts to get grainy, changes colour or smells strange, then it's time to replace it. It’s also a good idea to buy new sun cream for a new season, even if there’s a drop left in last summer's bottle.

There’s no research to show that the use of sunscreen can lead to vitamin D deficiency. Being in the sun for about 15 minutes in the middle of the day during the summer is enough for vitamin D to be formed. In other words, your body easily produces vitamin D when it's exposed to UV radiation.

The WHO, the World Health Organization, advises people against sunbathing, as it’s the biggest contributing factor to skin cancer. If you suffer from vitamin D deficiency, the WHO recommends dietary supplements instead of sunbathing.

Sun cream stains on your clothes are a nuisance. Not only are they greasy, but they often become discoloured and take on a yellowish, dull tone. Try putting the stained garment in warm water and adding a small amount of uncoloured washing-up liquid. This may dissolve the stain slightly before you put it in the wash.

Be sure to rinse off the washing-up liquid thoroughly before putting the clothes in the washing machine.