Each summer is the same refrain. We are hammered that the SPF is non -negotiablethat you have to put back every two hours, that the best cream is the one that is applied (and above all, which we reappear). Result: our faces become the almost military layering theater.
Superposition of filters: when the composition complicates protection
With the rise of hybrid care, sun protection is no longer limited to a tube applied to the beach. We start the day with a SPF serum, we continue with a protective tinted cream, we finish with a mattifying powder also containing an index. All this seems logical, practical, and rather reassuring.
But the reality is a little less simple. Because no, the SPF indices do not add up. Applying a SPF 15 treatment under a SPF 30 cream does not raise you to a SPF 45 shield. In reality, it is always the index of the last product well applied in sufficient quantity that counts. And this is the catch: few are those that use the necessary doses for a foundation or a SPF powder to really fulfill its role.
Another key point, often ignored: filters are not all compatible with each other. Mineral filters such as zinc oxide or titanium dioxide, present in solar powders, can interact with the organic filters present in other formulas. Result ? A less stable, more fragile protection in the face of UV rays, especially if one of the filters is photo-instalable or encapsulated in a volatile texture.
The invisible dilution or displacement effect
Beyond chemistry, the gesture counts. By superimposing layers, rubbing or blurring a foundation after a sunscreen, we simply risk mechanically moving the filter initially applied. And this without realizing it. This gives an impression of routine “”, while certain areas of the face are partially, even completely, exposed.
Poorly fixed powder or fluid textures can also cause evaporation or migration of filters. And when each layer cancels anotherwe end up with ghost protection. All the more insidious as it gives good conscience.
What method to adopt to avoid interference?
Additional solar products such as powders or SPF foundations can serve as reinforcements, but never basic. For a simple, effective routine without risk of interference, it is better:
- Apply a SPF 30 or 50 sunscreen on clean and dry skin, without serum or base beforehand
- wait two to three minutes to let the product join
- Then apply your makeup by tapping, without rubbing
- Use a SPF powder or mist only for retouching during the day
This method limits the risk of movement, guarantees homogeneous protection And allows filters to fully play their role, without a conflict of formulation.
