SAFERSUN works with light. When exposed to sun (UVA rays, UVB rays, and visible light), the patch changes colour from transparent to purple. When exposed to visible light only (because the UVA & UVB rays are blocked by sunscreen), it changes colour from purple to transparent.

Because sunscreen blocks UV rays and lets through visible light, SAFERSUN remains transparent as long as the sunscreen is effective. As soon as the protection wears off and the UV rays get to the skin, the patch turns purple.

Thanks to the patented “dermatrue” skin-imitating system, the UV protection on the sticker behaves exactly like on the skin. If the SPF value is 10 or less, the patch changes colour, giving a preventive warning that it’s time to apply a new layer of sunscreen.

Without sunscreen, the patch may turn purple in about 30 seconds in direct sunlight. With sunscreen, the change from purple to transparent lasts up to 1.5 minutes in direct sunlight.

When applying sunscreen, several factors affect how quickly the colour changes:

  • the UV index
  • amount of time spent in the shade vs. in the sun
  • how high the sun protection factor is
  • how much sunscreen was applied
  • how long the sunscreen can dry on the skin and on the sticker
  • which activities are carried out (swimming, sweating, sunbathing etc.)

All sunscreens recommend re-applying after swimming or drying, so the colour of the patch will change as you get out of the water.

SAFERSUN is hypoallergenic, suitable for children and dermatologically tested.

Our patented, skin-mimicking technology was developed based on Fitzpatrick skin types 1 and 2 (the fairest ones). Clinical studies have confirmed that, regardless of the skin type, SAFERSUN keeps you protected in the sun all day, as long as you apply enough sunscreen to keep the patch transparent.

You’ll probably notice that you need a lot more sunscreen to stay protected than you thought.

There are several possible reasons why the sticker changed colour so quickly. First, it depends on how you use the sunscreen, where you are and what you do, and what type of sunscreen you use.

A common misconception about sunscreen is that you only need to apply it every few hours. In fact, it is much less effective than most providers promise. This happens because of the way most companies test water resistance. This test does not include physical activities. If you go into the water and swim, use a towel and dry yourself, or do a sweaty workout, the duration of protection will be shorter. That is why we developed SAFERSUN. Once the protection is only SPF 10 or less, the patch turns purple and gives a clear signal to re-apply sunscreen.

You need a lot more sunscreen than you thought! Most people only use a third of the amount that would be needed. If you do not apply enough, your SPF50 is really just SPF5. SAFERSUN shows exactly how much you need to be protected and to get the most out of your sunscreen.

For more information, just let the product answer the question “How long will it take for my patch to change colour?”.

Your STICKER should be purple when put on as it shows the colour you see when you are not protected. If you followed the instructions and your sticker is still transparent, try the following:

  • Make sure you have put sunscreen on the sticker. Wait until the sunscreen has soaked in the STICKER. This takes about 30 seconds, only then rub in completely.
  • Make sure your STICKER with sunscreen is exposed to direct sunlight
  • Avoid touching the STICKER after applying the sunscreen, as this will remove the protective layer
  • Check the expiration date of the sunscreen. Once expired, it is no longer effective.

Reminder: SAFERSUN needs sunlight to change colour. The STICKERS also change colour indoors or in the shade, but it takes much longer than in direct sunlight.

If the sticker is still transparent, wear more sunscreen. You probably did not use enough. Most people use too little sunscreen. The majority of people only use 25 percent of the amount of sunscreen they would need to get the SPF indicated on the pack.

There are a few reasons why the STICKER does not turn purple. One of them might be that you apply your sunscreen correctly and are therefore protected.

Another reason could be low levels of ultraviolet radiation in your area or other environmental conditions.

SAFERSUN works with most sunscreens. We recommend a mineral filter with SPF 30+, broadband (protects against UVA and UVB rays) and waterproof for at least 80 minutes.

SAFERSUN does not work with alcohol-based sunscreen such as gel-based sunscreen or aerosol-containing sprays.

No. The STICKERS are suitable for repeated application of sunscreen. The purple colour will change as soon as it is creamed again and the STICKER will be accurate throughout the day. At the end of the day, remove the STICKER and dispose of it.

After a day, the adhesive layer of the STICKER is not reliable any more. To make sure it holds firmly, we recommend that you do not wear the STICKER for more than a day.

The STICKERS are waterproof, sweat-resistant and towel-proof. You do not need to worry about the STICKER dropping off. They are designed to withstand a day on the beach.

Should the applicator detach from the STICKER, it is not a problem. You can simply remove the sticker yourself from the foil and stick it on your skin as usual.

Apply the STICKER in a place exposed to the sun. We recommend your forearm as long as it is not covered by clothing.

Avoid hairy, oily or sweaty areas. Skin pre-treated with lotion or the edges of clothing. And do not forget: apply the sunscreen over the STICKER, not below it.

Tan, just like sunburn, is a sign of damage caused by the sun. If your STICKER remains transparent throughout the day and you have applied enough sunscreen, it does not leave any imprints. We have never received reports of imprints until now.

First put the STICKER on, then spread the sunscreen over it.

The STICKERS are equipped with a medical adhesive that holds reliably. Place the sticker in a clean, dry place. Your upper arm just below the shoulder is fine, as long as it is not covered with clothing.

If you follow these tips, the sticker stays in place all day long:

When putting it on, choose a spot that is as free of hair, oil and sweat as possible. The skin must not be pre-treated with body lotion and the STICKER should not come into contact with the edges of the clothing.
After swimming or hand washing carefully dry and softly dab the STICKER with a towel.
Avoid touching the STICKER unless you apply new sunscreen.

Safety is our main focus from the beginning. We went through the toughest tests to confirm that the STICKERS are safe.

Imagine the STICKER as a three-layer system:
Top layer: the first layer consists of the patented material that mimics the properties of your skin. In clinical trials, we were able to confirm that this material reacts with sunscreen just like human skin.
Middle layer: this is where the dye is printed on the underlying adhesive layer
Base: the bottom layer consists of a certified medical adhesive

All contents, apart from the colour-changing ink, have long been used in cosmetic products or in consumer applications. All substances are tested and safe.

With the colour-changing ink, we conducted six standardised tests to demonstrate the safety of the material.
The dye we use passed all tests with the highest possible safety value.

The dye is completely safe and apart from that, it does not come into direct contact with the skin. Like a sandwich, it lies between the base and the top layer.

The certified medical adhesive is hypoallergenic and suitable for sensitive skin.

We performed clinical trials confirming that the SAFERSUN changes colour at exactly the right time, as soon as the SPF 50 reaches SPF 10. In addition, the tests proved that our skin-imitating material retains sunscreen for as long as our own skin.

We use the same technique that world’s leading academics use to measure sunscreen on their skin. You can read about this technique in great detail in our reports. In short, we use alcohol swabs to measure the sunscreen on the skin. For quantification purposes, we use UV/Vis spectroscopy.

And we compare:

The amount of sunscreen that is removed by the alcohol swab
The amount of sunscreen on the STICKER
The colour of the STICKER in the sun

We check that (1) and (2) have the same amount of sun. Then we check if the amount of sunscreen is above or below 0.8 mg/cm2 and compare the colour with that of the STICKER in sunlight (3). The test is successful if (1) = (2), and (3) has the correct colour on the surface. (purple at 0.8 mg/cm2, otherwise transparent).

By repeating this procedure, you can track how the sunscreen behaves on skin and on the STICKER.

This shows: if the STICKER turns purple, there is an effective sun protection factor of 10 on the STICKER and thus also on the skin. In this case, the user should apply a new layer of sunscreen as soon as possible.