Introduction
If in the past light skin was a sign of a high social status - in contrast to the darker one, characteristic of a life of hard work in the fields - today, tanned skin is synonymous with health, youth and beauty, and evokes images of vacation, relaxation and well-being.
At the same time, thanks to the dissemination of information on the possible damage caused by exposure to the sun, people are increasingly aware of the importance of solar products in protecting the skin from damage caused by ultraviolet rays, and in favoring a gradual tan and lasting, thus preserving the health of one's skin.
Article Index
Solar productsTypes of solar formulationsSolar filters and tanningSkin pigmentationSunlight: effects on the skin SPF of sun productsFrom the cosmetology section
Electromagnetic radiation and filtersSolar filtersChemical filters Physical filtersProducts after sunAuto tanners and depigmentantsDHA - DihydroxyacetoneSolar products
Solar product means "any preparation (such as cream, oil, gel, spray) intended to be placed in contact with human skin, for the exclusive or principal purpose of protecting it from UV rays by absorbing them, dispersing them or by refraction".
Sunscreens must have a good toxicological profile, be nouns as much as possible on the skin, they must be photo-stable and must provide broad-spectrum protection. Furthermore, it is important that a careful selection be made of the other ingredients that make up the formulation of the solar product; for example the perfume, if inserted, is preferable not to contain allergenic substances. Moisturizing, protective and photo-aging substances, such as antioxidants, cannot be missing: these molecules can contribute to photo-protection both by increasing the degree of absorption of UV radiation and by their antioxidant activity: plant extracts rich in polyphenols, by virtue of their anti-radical function, they are able to protect against immunosuppression and DNA damage caused by ultraviolet radiation; similar effects have been recognized to extracts of green tea conveyed in solar formulations and applied to the skin, and to antioxidant vitamins, such as tocopherols, tocotrienols and vitamin C.
Other key ingredients used in the current photo-protection are the so - called SPF-Booster, raw materials that, with different mechanisms of action, are able to enhance the SPF of a solar formulation and thus allow the reduction of the concentration of chemical filters and physical. In order to achieve a boosting effect, some companies propose the use of emollients (eg esters such as Octyldodecyl neopentanoate or C12-C15 alckil benzoate), able to favor the dispersion of filters, thus increasing their effectiveness o, alternatively, copolymers with film-forming and ultraviolet radiation-reflecting properties, such as Polytetrafluoroethylene or Tricontanyl PVP.
Types of Solar Formulations
Solar Oils
They come from natural oils, such as walnut husks or olives, and are the oldest cosmetic vehicles. They allow an excellent dispersion of sunscreens (almost all liposoluble) and do not require the presence of preservatives. However, they do not guarantee high protection due to their extreme spreadability and the formation of a transparent, water-resistant, but thin film. They are suitable for darker skin types or for those who are already tanned. They are the ideal vehicle for protecting hair from photoinduced damage (dryness, weakening, loss of color).
Stick, Lipogel or Anhydrous Gel
They are similar to oils, but have a solid form, often rich in vaseline or mineral oils; their application is limited to restricted skin areas because they can be sticky and greasy. The sticks are indicated for small sensitive areas, such as the face, to cover the already existing solar hyperpigmentations and avoid their deterioration or to protect surgical and recent scars.
Hydrogel
Water-based, or rather hydroalcoholic (with ethyl alcohol) jellies. Beautiful to see, they give an immediate feeling of freshness. However, they form a transparent film, not sufficiently homogeneous and guarantee low protection. Furthermore, the presence of alcohol is not recommended for children, for those with sensitive skin, dry or aging skin. The gel form is instead excellent on the hair (polishing and fixing effect) or as after-sun products (in this case alcohol is not present) with a repairing action on sun damage, refreshing, soothing and moisturizing, with high percentages of phytoderivatives and active substances .
O / W and W / O emulsions (Oil in water-Water in oil):
They are biphasic systems that contain both an aqueous phase and a lipophilic component (fatty substances such as oils, waxes, etc.). This allows the use of a high quantity of protective substances, both physical and chemical, to modulate the formation of a film (protective thickness) on the skin surface, to guarantee resistance to washing and sweat removal.
Due to their greater resistance, lipophilic continuous phase emulsions (water in oil) or recent silicone water, with high application pleasantness, are to be preferred. The most common and light emulsions with continuous aqueous phase (oil in water) are pleasant, but they resist less to baths and sweat and require the presence of greater quantities of preservatives to avoid microbial contamination. To recommend to those who want a strong cosmetic functionality, emulsions combine sun protection with many features, including: hydration, protection from free radicals, anti-wrinkle action and many others. To avoid microemulsions (transparent in appearance) due to their high capacity of skin absorption.
Paste and Creme Dense
Suitable for children, hypohydric emulsions (water in oil) are prevalent with a prevalent base of physical protective substances, with surface skin action. They are poor in preservatives and additives, fragrance-free and strictly controlled in terms of photostability.
Solar Water
Liquids in refreshing and perfumed sprays, with low or very low level of sun protection. They contain mixtures of water, chemical filters, perfumed essences and alcohol. To be avoided in the presence of light or sensitive skin. They respond more to a fashion than to a real need for protection from sunlight. [1]
BIBLIOGRAPHY:
[1] Ultraviolet rays and sun protection, Istituto Superiore di Sanità - Press release n. 15/2004.
After-Sun Products
Prolonged exposure to solar radiation can cause dehydration and peeling of the skin. To restore the optimal physiological conditions and restore the skin hydro-lipid barrier, it is recommended to use after-sun products. The primary function required for this type of product is moisturizing, often combined with refreshing, soothing and decongestant effects.
For this purpose, there are many substances used in after-sun products, starting with the moisturizing active ingredients, such as panthenol, trehalose, allantoin, trimethylglycine; extracts with soothing activity, such as aloe and calendula; refreshing like menthol. Some products may contain accelerators or tanning extensions such as tyrosine, or substances with insect-repellent activity that can be achieved, for example, with natural derivatives such as andiroba oil. The most common cosmetic forms are O / A emulsions and water-based gels, which offer the advantage of rapid evaporation with a cooling effect.
