• The Application of Sun Cream

The Application of Sun Cream; You Probably Apply Less than You Think

No other subject within skincare causes so much confusion as the application of sun cream. Inaccurate reports on the internet and in the papers, false product claims and unfounded regulations have led to us all going about it in the wrong way! And as a result of this; lying on our beach towel in the sun probably causes more damage than if we’d put on no sun cream at all. To put it simply, we spend too much time in the sun because we think we are protected, which we are not. Therefore giving us a false sense of security!

Correct application: which factor…

SPF stands for Sun Protection Factor. At the present time in Europe, the SPF can be determined after being tested on a minimum of 10 people. What happens in such a test: 2 milligrams of the sun cream is applied to each cm2 of skin. The SPF is determined by dividing the minimal erythema dose (MED) on an area of protected skin by the MED on an area of unprotected skin, the MED shows how much energy per cm2 s required in order to keep redness to a minimum. An area of unprotected skin on a skin type 2 uses, in general, 200 joules of energy to keep redness to a minimum. When an SPF 15 is applied, the area of protected skin changes colour after 3000 joules of UVB radiation. Or in other words: you can stay in the sun up to 15 times longer than normal. SPF testing is, however, not truly accurate and is carried out by commercial agencies. According to a survey carried out in the Netherlands, the results aren’t always reliable. An investigation in the United States of America came up with similar results. I am very pleased that, at present, studies are being carried out in France. They are mainly occupied with finding an alternative way of assessing the SPF classification of sun creams. So a little patience may be needed!

Just remember: no product gives full protection in the sun. Not even application of an SPF 50 or ‘sun blocker’. You can assume that when you use an SPF 15 that you will receive around 93-94% protection. Application of an SPF 30 gives you approximately 97% protection while an SPF 50 provides an additional 1 to 2% more than the factor 30.

What should I protect against?

The SPF on the packaging informs you about the protection against UVB damage but not so much about the UVA damage. Please note that you choose a sun cream that protects against both UVB and UVA radiation. UVA radiation doesn’t burn you, so you don’t see any warning signs from your skin either. But UVA rays are potentially more damaging than UVB rays. They penetrate the deeper layers of the skin causing damage to the DNA and premature ageing. The connective tissue is harmed and the skin begins to lose its elasticity. UVA rays also increase the risk of getting skin cancer. Sunlight contains 20 times more UVA than UVB radiation. According to the new regulation the UVA protection factor must be at least 1/3 of the UVB protection factor. Products achieving this display a circle with the letters UVA inside it on the packaging. Unfortunately not every manufacturer is at this stage yet. This is very apparent in America where many products on the market provide barely any UVA protection at all, even though UVA radiation is far more damaging than UVB radiation. So this means that one product with SPF 30 can provide much more protection than another product with the same protection factor.

Another interesting fact is that not only UV radiation causes damage but also infra-red radiation. Infra-red causes free radicals to form and damages the collagen. Sun filters are ineffective against this radiation but antioxidants are effective. In order to limit the damage which is already present, it is worth applying antioxidants onto your skin. The summary of a recent study into infra-red radiation and whether it is actually damaging to the skin can be read (in Dutch) at Skinwiser: http://bit.ly/1dXn8Li & http://bit.ly/1MrR1gv.

Application of sun cream: how to do it right

Considering the fact that 2 milligrams is tested on a cm2 of skin, it is important that you also apply this amount on yourself in order to receive that protection factor. Shocking but true: on average people apply a mere 0.5-1 mg per cm2 meaning that your SPF 30 is providing you with a meagre SPF 9-16. Read more about the correct application and how that affects the protection factor at Skinwiser: http://bit.ly/1GkXDOj.

It is not bad either that 2 milligrams per cm2 is almost impossible to wipe away. Always remember that you are probably less protected than you think.

Left: the amount we usually apply on the face.
Right: the amount we should be applying on the face.

The powders containing an SPF are a real problem. With these not even a 10th of the SPF that is required is applied in order to reach sufficient protection. Just remember that when you are relying on the SPF in your foundation or bb cream that you are never getting the SPF which it promises. That would mean plastering it on.

My advice, always apply a sun product separately if the UV index is 3 or above. This is roughly between April and September. And it goes without saying, re-application is needed every couple of hours…

Which sun cream

I am so disappointed that there are still so many products with poor sun filters on the market. I am not going to discuss safety today, but I am going to tell you about filters which lose their effectiveness in sunlight. As strange as it may seem, a number of filters are affected by the sun and certain filters, when combined, are completely powerless against the sun and after just a few hours will barely protect your skin (or weeks when stored in the bathroom cabinet). These are often the UVA filters and you won’t notice because you don’t burn. A good example of this is the combination of avobenzone and octinoxate. And then let this combination to be used in that one all day sunscreen!

Please be aware that if you are in the sun, you should avoid using so-called phototoxic substances. These are substances which, when combined with the sun, can accelerate sun damage without you noticing on your skin. You may also be left with ugly pigmentation spots. Substances which can cause this (and sadly these are also often found in sun creams) are: fragrances/perfume, colourings, plant extracts/oils (such as citrus, orange, bergamot, mandarin, grapefruit, lime, lavender, rosemary, fig, angelica, St. John’s wort, tea tree and ginger) and oxybenzone (strangely enough that is a sun filter).

Shelf life

Sun creams should display an ‘open jar’ symbol on their container. This means that a sealed product has a shelf life of at least 30 months. If the product has been opened then it has a number of months left which will be displayed alongside or above the ‘open jar’ symbol. But: an important point here, this shelf life indicator is about the risk of contamination of the product and the stability of the cream, and not so much about the effectiveness of the sun filters. Certain chemical filters definitely lose a lot of their effectiveness, and so to be sure, I recommend buying a new sun cream each year. The chances of the effectiveness of a product being lost are increased more when exposed to heat and light (and this is inevitably when you take your sun cream with you to a sunny resort). So a new product each year!

You can find out much more about the sun and sun protection in my sun booklet (in Dutch) from the ‘Smeer je in!’ campaign. Including, among other things, how to equip your skin for the sun, is an after sun necessary, spray or rub in, are more expensive sun creams better and what about waterproof sun creams?


Regards Jetske
(Dr. Jetske Ultee-Research Physician Cosmetic Dermatology)