My husband has been training for some marathons and sometimes swim under the hot scorching sun when the UV index is about 13 or 14. Normally, he uses La Roche-Posay Anthelios XL SPF50+ on his face and neck only but recently, I helped him apply UV Natural Sunscreen SPF30+ on his entire body because the formulation is highly water resistant. In addition, I got him to take two of the Heliocare oral sunscreen protection capsules. So eventually when I checked him, he was not burned, but did appear slightly darker. However, he complained that it was difficult to wash off.
Do not contain emulsifiers and are water insoluble
I found out that in order to provide proper protection when exposed to water, sunscreens that are labelled as water resistant are very difficult to wash off because they’re not water-soluble. Hence, most good sunscreens that are of water resistant formulas have no emulsifiers, because this allows the cream to stay on the skin until you wash it off with soap. Either that or the formulation is characterized by a water insoluble film so as to create a longer lasting effect and the product has the same protective action during and after swimming.
Bottom line: So if you’re using a sunscreen that is easy to wash off with just water, despite being labelled as waterproof or water resistant, it is not going to provide you with adequate protection when you use it for swimming.
Contain alcohol for easy re-application
Until I applied the UV Natural Sunscreen on my husband, I didn’t realize that it is quite difficult to rub on and I discovered that this is because it does not contain alcohol as formulations using alcoholic solution allows for multiple coatings to be readily applied (source). According to the FDA, a â€œwater-resistantâ€ sunscreen loses its SPF protection after around 40 minutes of water exposure whereas a â€œwater proofâ€ sunscreen loses its SPF protection after 80 minutes of water exposure. So even though it is stated on UV Natural Sunscreen that it is water resistant for up to 2 hours, it is better to re-apply after 40 minutes. However, the formulation makes it difficult to do so properly.
Bottom line: So if you’re getting a water resistant sunscreen, consider one containing alcohol which makes re-application a breeze.