Cheat Sheet - SPF UPDATED

Cheat Sheet - SPF UPDATED

When purchasing SPF the main questions to ask are:

What is the SPF?

Is it a Broad Spectrum product? There are two main concerns from being in the sun: Skin-ageing and skin cancer.

UV Light causes sun burn and sun damage by damaging cellular DNA.

UVA (long-wave) causes the ageing and UVB (short-wave) causes the burning.

Both the U.S. Department of Health and Human Services and the World Health Organization have identified UV as a proven human carcinogen. Therefore, there is no such thing as a ‘safe tan. A tan is a sign of DNA damage. It is the result of a chemical reaction in your body as it tries (and fails) to protect itself from UV light. Brands selling SPF that use the term ‘safe tanning’ are at best misleading and at worst, clueless.

The majority of sun damage is done in the first 20 years of your life. Age spots/pigmentation appearing when you’re older are the fault of those Spanish teen holidays – not just the tan you got in Newquay last year. ;)

‘Natural’ vs ‘Chemical’ Physical (most commonly referred to as ‘natural’ in marketing materials) advertises that it reflects the UV light. Traditionally, 'chemical' SPFs advertise that they absorb the light. The truth is somewhere in the middle. Physical sunscreen, contrary to popular belief and the GOOP website, is not ‘natural’, nor not a chemical. Scientifically, physical sunscreens are classed as 'inorganic' and the more traditional 'chemical' SPF is 'organic'. The irony. Zinc and titanium oxide are not biodegradable and also frequently use nano-technology, which is under question by cancer research bodies because of its possible links to cancers in humans. If your preference is to use ‘natural’ your closest bet is a ‘non-nano’ oxide. Bear in mind it's still technically a chemical, no matter what the EWG say. The term non-nano means nothing to the FDA, but it may be better for you.

Government Guidelines FDA standards are different from Europe and Australasia. In the USA, SPF labelling is a requirement because the FDA says it is a drug. In Europe, it is classed as a cosmetic and therefore stating SPF classification is not mandatory, it’s just for information.

Having said that, European manufacturers are allowed to use seven proven UVA filters whilst the FDA in the USA only allows three, meaning that technically a European product has the potential to be more effective than an American-made product.

SPF is only relevant to UVB light. PPD - Persistent Pigment Darkening is one way of measuring UVA light but is now considered out-dated. The PA++ system, developed in the East Asia is another method used – however neither of these are allowed when making broad spectrum claims in the USA. It’s enough to make you tear your hair out.

An in vitro test to gauge a Critical Wavelength is really what a brand should be able to show to claim Broad Spectrum on their packaging in the US and the UK. Critical Wavelength tests measure the absorbance of UV light on skin and a critical wavelength of 370nm is what you are looking for on literature. Not that many brands will bother labelling that information but do your research or ask them directly.


  • SPF does not accumulate. If you wear a moisturiser, primer and sunscreen you will only have the highest SPF that you are using, you cannot ‘add them up’.
  • Pre-cancerous moles are a myth. They are either cancerous or they are not. If in doubt, cut it out. A mole is a benign lesion. Any changes, any – it needs to be checked by an expert and removed.
  • Acne sufferers: whilst the sun may have a drying effect on your acne; but a lot of SPF products are comedogenic. Use oil-free sunscreens if possible. Avoid mineral oil in sunscreens (and your normal skincare).
  • Darker skin, whilst not as vulnerable to UV light as lighter skin, still needs to protect itself from UV damage and use SPF. Although darker skins can stay longer in the sun without burning and they do not need the same high factors as a Type 1 person, they should still use SPF.
  • No sunscreen is waterproof. They can only be listed as ‘water resistant’.
  • SPF should be repurchased fresh every year. It degrades.
  • Do not waste your money on a really expensive anti-ageing moisturiser with SPF. SPF is an all-encompassing product that will overtake any active/expensive ingredients in your skincare. Use your expensive skincare and apply a separate SPF on top.

‘Cruelty-free’. Never were more ingredients tested on animals in the beauty industry than SPF products. This does not mean the final product is tested on animals, meaning that brands that state they are against animal testing are not technically lying, it means the raw ingredients were, at some point, absolutely tested on animals in a lab to ensure ‘efficacy’, especially in the USA, where they are classed as drugs. Whilst this is true of the entire beauty and health industry, I mention it not to make you feel bad, purely to counterbalance the nonsense of ‘vegan, animal-friendly, non-toxic SPF 50’ claims that are frankly, nonsense.

PETA can say there are a wealth of cruelty-free brands * but the reality is that the ingredients were tested on animals at some point. They may be cruelty-free now, but the ingredients have probably been tested on animals historically. Again, not being negative, just giving the full story.

Even Lush, the champions against animal testing and ‘natural’ claims, use octocrylene and octyl methoxycinnamate, both chemical UVB sunscreens. Again, I am in no way singling out Lush, merely offering balance to the over-use of the word ‘toxic’ in scare-mongering media and frankly, some lies written by marketing departments and celebrity websites.


  • SPF is the last product to be applied to your skin after moisturiser and before makeup.
  • Apply 2mg per Square CM which equates approximately to one teaspoon for your face and neck, two per chest, two per back, two per arm, two/three per leg depending on your height obviously. If you are particularly tall, or have a large frame, obviously use more. I use a tablespoon for face, neck and décolleté (fat head) - and I’m 5’11, so I use two tablespoons per body part.
  • Reapply every 90 minutes to 2 hours or more often if in water.


If you have children the best advice is to cover them up and keep them out of direct sunlight as much as possible.

  • Reapply their SPF every 90 minutes, more frequently if they are getting wet.
  • If you have boys with short hair, remember the back of their necks and their ears. Every single person I have seen under a Wood’s Lamp has significant sun damage at the tops of their ears (women typically apply their SPF before they hit the beach and put their hair in a ponytail the minute they sit on the sand - EARS!) and above the eyebrows – and it’s always worse in my Australian clients. (Sorry Aussie friends – it’s true).

When asked what he would use on his child, Dr Marko Lens replied: ‘I would probably put a chemical sunscreen on my child. I would not feel comfortable using nano-technology on my child.’

And finally, my most-asked questions from my readers:

  • Personally, I would not dream of using a ‘once a day’ sunscreen on holiday, especially on my children. Where once a day formulas might come in handy are…
  • Young children going to school. If, as mine do, your young children attend a school where the teachers are not allowed to touch the children, even with your permission, a once a day formula may be a good option. Your children may sweat a little, but they aren’t in the sea so should be protected still by 3.30pm. In theory. It still makes me uneasy, but it’s better than applying a typical 'kids' SPF15 at 8.30and that’s it for the day…. It’s your judgement call as a parent/carer.
  • If you are wearing SPF under your makeup and going to work you will probably not be covered by lunchtime. You either need to reapply (not likely I know), use a once-a-day product, which are far better suited to city living than beach in my opinion, or buy yourself a big hat and be done with it. You could also use…
  • Sprays. Here’s the thing with sprays: you have to make sure you have covered the entire area thoroughly and that is unlikely unless you are applying it to your child, in which case most of us show more due diligence than when we are applying to our own bodies. Use a spray over your makeup if you know you have applied it evenly and feel protected, otherwise, go down the once a day route or make like Jackie O and enjoy a hat and sunglasses. There is also cause for concern when inhaling sprays - something you will invariably do if the point is to apply it over your makeup. Your judgement call.
  • I am frequently asked about Institut Esthederm. They are a tanning brand, not an SPF brand. Make of that what you will.
  • It is safe to use all of your actives in your skincare in the summer – just make sure you are using your SPF.
  • If you wear SPF please double cleanse!


*FDA SPF Guidelines:

FDA on Animal Testing/Cruelty-free:

Find more answers to some of the most common SPF questions over on the Skin Rocks Column.

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