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Let’s Talk SPF!

In my previous blog I explored the question of the dangers of screens’ blue light, and whether exposure to the light from screen devices can damage our skin, in the same way as the sun, and should we therefore be protecting it by applying an SPF compound as a part of our daily skincare routines.

In order to answer this question, I touched briefly on the application and purpose of SPF, and I will now spend a little more time looking at an area of skincare that has exploded in the past few decades. The reason for this?  We now have access to numerous research studies that link the appearance of signs of aging on the skin such as wrinkles, sun and age spots, sagging and ultimately melanoma (or skin cancer) to unprotected sun exposure. Hence the use of skincare products containing ingredients that will protect the skin against damaging sunrays

What is SPF?

SPF, which stands for Sun Protection Factor, is the measurement of the efficacy of the product as in the amount of solar exposure needed to cause a sunburn when skin is protected with such SPF, relative to the amount of sun exposure needed to cause a sunburn without protection. A common misconception is believing that SPF is only related to the time of exposure. There are many factors that could affect SPF including the intensity of the sunrays, which is tied to the specific time of day, location (intensity is not the same on the Equator as it is at the Arctic Circle), and season; your skin type and specific conditions; and even the circumstances surrounding you on the day of the exposure, such as diet, hormonal changes, amount of sleep you are getting or the stress you are under, to name the common ones. These are all reasons why when it comes to protection, erring on the side of caution is always a must. Not only should you choose a high SPF product, but also apply it often and compliment it with other protection such as a hat, sunglasses, and comfortable clothing when outdoors.

What is UVA/UVB?

What is with UVA/UVB and all those rays? The sun emits radiation, which consists of waves traveling through space carrying energy. There are several types of radiation: gamma rays, x-rays, ultraviolet (UV), visible light, infrared (IR), microwaves (or MW, which are the ones your oven uses to heat up) and radio. Each type is defined by wavelength and frequency, which are inversely proportional, and energy, which comes from the wave-particle duality of radiation. Although the sun emits many of those types, for the sake of the topic of SPF, let’s focus on UV, visible and IR radiation, the most common we can be exposed to when in daylight.

Visible light is, as its name states, the one our eye can perceive and is responsible for allowing us to see, IR is the one causing heat, and UV is the highest in energy, and the one we need the most protection from. When we expose our skin to the sun, UV rays can penetrate through its different layers, causing excitation of the molecules and potential permanent damage, ultimately resulting in melanoma. The radiation spectrum is a continuum of progressively higher wavelength/lower frequency waves, with different subtypes within the same kind. For example, UV waves can be UVC, UVB and UVA, in order of decreasing energy. The higher the energy, the higher the penetration through the skin and the “damaging potential”, which means that UVC rays are likely the most harmful and UVA the mildest. The reality is that it is important to protect ourselves against ALL of them, which is why “broad spectrum” applies, to indicate that it covers the entire range.

Two Types of Protective Skincare

There are two types of protective skincare, which I described when previously exploring the dangers of screens’ blue light, these are chemical and physical. All the ingredients that provide SPF to the so-called “physical” are also chemicals, and in fact, one can argue that is true for all the ingredients in a formulation no matter their name, but I am digressing. I prefer to call the two types: inorganic (or mineral) and organic (nothing to do with coming from plants or renewable resources, but referring to the chemistry of carbon, which is the chemistry of living organisms).

  1. Organic (or chemical) SPF. These contain ingredients that can absorb UV rays, preventing them from reaching the inner layers of your skin. The absorption results in the decomposition of the molecule and the release of a small amount of thermal energy. In fact the same type of ingredients are widely used in the coatings and adhesives industry, as photoinitiators in those UV-curable formulations that generally use no solvents (100% solids). Have you ever wondered how the gel manicures polish works? They are UV-curable, photoinitiator containing. There are many types of them, classified by the type of UV radiation they absorb. Therefore, to have a broad-spectrum SPF, a balanced blend of this type of molecule is needed. They are generally not required in concentrations exceeding 10%, and can be dissolved in commonly used components of skincare formulas. The result is easily absorbable product with no residue.

    There is however a big controversy surrounding them, since they are allegedly harmful to marine life (including coral reproduction) and could potentially cause irreversible damage to the skin. After all, when they decompose upon UV contact, they can on many occasions give off the infamous “free radicals”, which are highly reactive, short-lived molecules (because of the unpaired electron), widely known for triggering the formation of “signs of aging”, such as wrinkles or sagging, as they may cause collagen degradation.
  2. Inorganic (mineral or physical) SPF. These incorporate minerals such as zinc oxide and titanium dioxide, which have historically been thought to have barrier properties as they reflect the UV rays, impeding their penetration through the skin. Lately a new theory has surfaced, which states that these ingredients can transform UV rays upon skin contact, making them less harmful. I personally believe it is a combination of both: less radiation makes it through and those rays that do will be subsequently transformed into lower, less or non-damaging energy.

    Because of the way they act, their ability to filter all types of UV radiation is the same, and as long as the amount incorporated is adequate, one should assume that “broad-spectrum” is a given. Unfortunately, the amounts required to achieve a certain SPF level are high, and the ingredients used to obtain it are bulking agents, which means that they increase the viscosity when in solution. This explains why mineral SPF is thicker, more difficult to spread and in occasions, uncomfortable when worn.

Choosing the Right Packaging Materials

It is crucial to choose the right materials to make the package that protects your SPF formulation, as by law the factor that the product has once it’s in the consumer’s hands cannot change from the one indicated on the packaging. This is the reason stability testing in the final package chosen must be conducted, and if there are any packaging changes post-launch, an expert must evaluate and deem whether retesting is necessary.

When PCR materials are used (in any given amount) for packaging, it is very important that the mechanical and chemical properties of such materials are identical (or close enough) to those of the virgin counterpart, as exposure to outside elements can affect all the formulation ingredients. This is particularly imperative when the SPF being considered is chemical (or organic). The ingredients that provide the protection from the sun are very sensitive to oxygen and radiation, so any loss in barrier properties, opacity, cracks formation and propagation, could result in exposure to those elements and degradation of the ingredients, which could result in a product SPF change.

When the product contains only mineral ingredients, this is still very important but to a lesser extent, as the ingredients that impart the filter to the formulation are almost insensitive to the elements. However, a poor barrier could still affect many other components resulting in SPF variations.

Protection is Their Purpose

Regardless of the type of SPF used, it is important to remember that applying these actives does not result in a health benefit to the skin. Protection is their only purpose. Therefore, only apply when you are outside, and supplement skin protection against the sun with clothing, glasses, hats, and other accessories. You can look fabulous while prolonging skin’s youthful look.


  • Dr. Marta

    Supported by a BSc. in Chemistry, MS in Polymer Science and doctorate in Polymer Chemistry, Dr. Marta began a fifteen-year journey into the health and beauty industry ultimately leading to the founding of “dr. mp”, a company dedicated to among other things, formulating skincare products for private labels. She is the author of many informative blog articles.

Dr. Marta

Supported by a BSc. in Chemistry, MS in Polymer Science and doctorate in Polymer Chemistry, Dr. Marta began a fifteen-year journey into the health and beauty industry ultimately leading to the founding of “dr. mp”, a company dedicated to among other things, formulating skincare products for private labels. She is the author of many informative blog articles.

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