Sunscreen products are always in high demand, yet formulating sunscreens is not as simple as creating other types of active formulas. There are regulations and limits on ingredient inputs, and the sunscreen needs to be formulated carefully to stabilize the UV filters while ensuring an even and effective spread. Finally, they are products that must be extensively stability tested – so need to be incredibly stable over a prolonged shelf life.
When is sunscreen cosmetic vs drug?
Sunscreen formulas are regulated as either cosmetics or drugs, depending on the country you are selling the product in and the SPF claim. Where a sunscreen is regulated as a drug or therapeutic good, it will need to go through significantly more regulatory checks and approvals, as well as require larger manufacturing quantities – which doesn’t always suit indie cosmetic brands.
For a quick overview, watch our video: Should your cosmetic brand have a sunscreen product?
There are also additional rules over ‘water resistance’ claims, warnings and certain label information required with all sunscreen products. Here is an overview of how different countries regulate products with SPF claims:
AUS | CANADA | China | EU / South Africa/ ASEAN countries / NZ | JAPAN | South Korea | USA |
Cosmetic:
SPF≤15 + SPF is secondary claim or color cosmetic or lip balm; OR Therapeutic: when SPF is primary function and/or SPF>15 |
Drug | Special use cosmetic | Cosmetic | Cosmetic | Cosmetic | Drug |
Do sunscreen formulas need to be SPF tested?
If the sunscreen formula is to claim an SPF rating, then it must always be SPF tested. The brand putting the SPF product into the marketplace is responsible for holding direct evidence of the SPF claimed for their specific product/formula. So even if the sunscreen has been formulated by a cosmetic chemist, manufactured under private label or you are using a formula from a supplier with stated SPF, the brand putting the product on the market MUST hold direct evidence for the SPF claims made by the product. This means no matter how you obtained your sunscreen formula, suitable evidence must be held by the brand putting the sunscreen product onto the market.
Don’t be fooled into thinking natural ingredients don’t need testing! There is misinformation out there that certain plant oils contain SPF protection, but they don’t. Watch this video where we bust the myths about natural oils reputed to have UV protection: Natural oils and sun protection.
SPF testing requirements vary in different countries – make sure the SPF testing conducted complies with the regulations where you intend to sell the product to ensure you hold the required evidence.
Organic and inorganic UV filters: What’s the difference?
There are two types of sunscreen agents:
- Organic sunscreens:
- Work by absorbing UV light.
- Also known as chemical sunscreen agents, however, they conform to organic chemistry principles.
- These materials are NOT permitted in natural or organic sunscreen formulas.
- Common examples include ethylhexyl methoxycinnamate (also known as octyl methoxycinnamate); benzophenone-3, ethylhexyl salicylate and homosalate.
- Inorganic sunscreens:
- Work by reflecting or scattering UV light to provide a physical barrier to UV entry to the skin.
- Also known as natural sunscreen agents, however, conform to inorganic chemistry principles.
- These materials ARE permitted in natural and organic sunscreen formulas but are NOT actually all natural.
- Common examples include zinc oxide and titanium oxide.
Why are combinations of sunscreen agents used in a sunscreen formula?
Because of limits on inputs of various sunscreen ingredients and the synergies and broad-spectrum results that can be obtained by using combinations of UV filters, formulating sunscreens with a range of UV filters will often give the best SPF results over a wide spectrum of UV light. Consumers are increasingly demanding high SPF protection with a great skin feel, which can be hard to achieve under the regulations without using a combination of materials.
UV filters have different wavelengths of absorbance or transmittance, which means they will protect against certain wavelengths of light in the UVA or UVB spectrum. To provide broad spectrum protection, UV filters must cover a large amount of the UVA and UVB spectrum, otherwise, they are not providing adequate protection.
For example, this is the protection spectrum of Escalol 517 (INCI: Butyl Methoxydibenzoylmethane):
In this graph you can see:
- The maximum wavelength of absorption is 357nm –but provides very little protection at 330nm or below.
- Using sunscreens with only one or two small peaks in the UVA and UVB spectrums will not provide suitable UV protection.
A combination of sunscreens that provide peaks in various places, over the wavelength range of 290 to 400nm is required to be considered broad spectrum and truly protective.
How to achieve the best SPF from sunscreen formulas
Even if you have a great choice of sunscreen filters in the formula, the SPF performance will be affected by:
- The way the product spreads: a smooth, even film on the skin provides the best SPF rating.
- Product stability: if the base formula starts to separate or form lumps over time, application will not enable an even spread of the sunscreen ingredients.
- Compatibility: UV agents cannot be allowed to agglomerate or crystallize over time, so they need a compatible formulation base to ensure a great shelf life.
To help you understand this principle, consider these images:
Both of these diagrams use the same quantity of incidental UV light (the arrows) and representative UV filters (the ovals). The image on the left provides an example of when UV filters agglomerate, thus allowing a lot of incidental UV light to pass through, resulting in a low SPF. The image on the right shows the same number of ovals, but in an even spread, to catch the most incidental UV light.
In reality, a combination of UV filters is commonly. In an even spreading, compatible and stable base formula, it could be represented like this:
Sunscreen formulas 101: Step-by-step guide
If you don’t know how to check or achieve any of the above requirements, then you should leave formulating sunscreens to a Cosmetic Chemist, or learn properly, with our Certificate in Advanced Cosmetic Science or Diploma of Personal Care Formulation.
When you’re ready, follow these steps to create great sunscreen formulas:
- Determine UV filters and input amounts required to achieve the required SPF (in theory)
- Check all inputs comply with local country regulations and cover the required UV spectrums.
- Determine suitable lipids to ensure compatibility and even spread of the UV filters.
- Add the lipid-soluble UV filter input + selected lipids to determine the total lipid input. This will determine if your formula is likely to be w/o or o/w. Most sunscreens with high SPF are w/o emulsions because of a usually significant oil + oil soluble component from the UV filters and solvents.
- Select the emulsifiers + polymers to stabilize the UV filters and suit the emulsion type.
- Check all inputs comply with local country regulations and are compatible with the selected sunscreen ingredients.
- Add compatible film formers for water resistance.
- Double check the formula for stability and compatibility – remember sunscreen formulas need to prove suitable stability so require rigorous stability testing and robust formulas.
Then it’s time to go in the lab and prepare sample after sample after sample! A great feeling, light-spreading sunscreen formula is not typically created right first go… so make sure you allow sufficient lab time to prepare multiple formula variations in order to get your sunscreen formula just right.
Happy formulating!
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