Chemical vs. Physical Sunscreens: The Science!

Chemical vs Physical Sunscreen - The Science

It’s the time of year when sunscreen becomes a ‘hot’ topic. If you were believe most of the nonsense out there, you’ll probably never use a so called ‘chemical’ sunscreen ever again. There are two common reasons why this might be:

  1. You’ve been told or read somewhere that ‘physical’ reflects UV where as chemical absorbs; making physical the better option.
  2. Physical contains natural ingredients so naturally, it must be better for you.

Oh, if only it was that simple and clear cut.

If you take a look at most of the ‘physical is better’ claims, you’ll generally find it comes from those selling ‘physical’ based sunscreens only. The skincare industry today is full of marketing hype and misleading information, which is why we lean on science to find the facts and reveal the truth.

Falling for this whole ‘physical is better’ nonsense without knowing the facts could cost you a lot of money, and you may end up using something that you don’t particularly like.

There are a lot of ‘theories’ out there but instead of giving you yet another ‘random’ theory with absolutely nothing to substantiate it, let’s take a look at the science.

This topic can get confusing so we’ve tried to make it as simple as possible to understand.

Chemicals Everywhere!

First of all, both physical and chemical based sunscreens contain chemicals. Sorry, but it’s true.

Have you looked at the periodic table lately? Titanium, Zinc and Oxygen are all on there – at least they were last time I checked. Together, they form Titanium Dioxide and Zinc Oxide, aka. ‘chemicals’. These are the key ingredients found in physical sunscreen.

For this reason alone, calling one chemical and one physical is not accurate and instantly leads to the believe that the one referred to as a ‘chemical’ must be bad for you. It’s not true. Thinking about them in this way has led to many people misunderstanding how sunscreen really works to protect the skin.

In chemistry, you would actually refer to the physical sunscreen as ‘inorganic‘ and the chemical sunscreen as ‘organic‘. Interesting, isn’t it!

Absorption & Reflection

Both chemical and physical absorb UV. Yep, sorry to burst that bubble for you!

Most of the marketing hype and nonsense on social media today would have you believe that physical reflects 100% of UV. This is only partly correct and there is so much information that get’s left out. We’ve done the research for you though and tried to make it as simple as possible to understand.

Cosmetic chemistry and the electromagnetic spectrum isn’t something high on most therapists lists to learn – but it probably should be. Even if just the basics. Most just repost images provided by the manufacturer – a manufacturer that probably only formulates physical sunscreen mind you. Fancy that! Considering most of these therapists also work with LED Light Therapy, it makes even more sense to learn about it.

UV light is divided into UVA and UVB (there are others but they aren’t relevant for the purpose of this article). Physical sunscreens predominantly absorb in the UVB (promotes skin Burning) spectrum and reflect in the UVA (promotes skin Aging) spectrum. Only about 5% of UVB light is reflected/scattered by physical sunscreens and the remainder gets absorbed – just like chemical sunscreens.

The argument that chemical sunscreens absorb heat producing more free radicals – essentially causing additional cell damage, increased risk of pigmentation, and whatever else you can come up with… is very weak. Given the sheer lack of evidence to substantiate these claims and the fact that both physical and chemical absorb UV, it shouldn’t be a reason to avoid chemical based sunscreens.

Physical vs Chemical Sunscreen Myth Buster

Natural is Best. No, it’s not!

We all love good, natural products. But you need to know when and where to draw the line.

Just because something is natural doesn’t automatically make it better or safer for you; just like something that is synthetic (man made) doesn’t mean it’s bad or unsafe for you.

While Titanium, Zinc and Oxygen are all natural, they are still chemicals in the world of chemistry. It doesn’t matter which way you try and swing it. When they are formulated into a sunscreen product, the Titanium and Zinc may even be coated in chemical substances in order to stop them from becoming photo-catalytic. Essentially, you have chemicals being coated in chemicals. This is just another reason why referencing sunscreens as chemical and physical isn’t ideal and gives a false sense of how they truly function.

If you’re still having trouble getting over the whole ‘natural is better’ thing – perhaps Google where Botox comes from. This ‘natural’ substance is actually one of, if not the most deadliest neurotoxins on the planet. Inhaling even the smallest amount is enough to kill you. But hey, natural is safer and better, right?

There are plenty of other natural ‘things’ out there that that can kill. From plants to toxins found in animals – the list is endless.

SPF Ratings

SPF stands for Sun Protection Factor. How does it work? If your unprotected skin takes 10 minutes to show signs of burning, then properly applying SPF 30 would slow the rate of burning to the point where it would take 30 times longer, or 300 minutes in total before the signs of burning will show. SPF 15 would take 150 minutes, while SPF 50 will take 500 minutes.

It’s important to note that SPF ratings only refer to UVB (burning) protection. It has no bearing whatsoever on UVA protection.

Having said that, this is almost ALWAYS going to be inaccurate because there are so many variables. First and foremost, most people don’t apply sunscreen properly nor do they use enough of it – so you’re SPF 30 is probably more like SPF 20 before you even go outside. Add in sweat, rubbing of cloths against your skin and so on and the number significantly drops again. This is why the general rule is to apply it every 1.5 – 2 hours (max) regardless of SPF rating – especially if you’re outdoors and active.

The difference between an SPF 30+ and SPF 50+ is about 1% extra protection. Yes, you read that correctly.

An SPF 30+ sunscreen applied properly will give better protection than a SPF 50+ sunscreen applied incorrectly or not frequently enough.

Do your research!

A random post on Instagram or Facebook by a clinic that only stocks physical sunscreen, or some beauty blogger ‘plugging’ some product they’ve received for free in order to review it should NOT, under any circumstances, be taken seriously. You’ll often certain brands who formulate a physical only sunscreen and will also publish blogs and articles with titles like “Sunscreen: The Facts” with a bias towards their physical sunscreen.

Remember, we are talking about cosmetic chemistry and the electromagnetic spectrum. Sunscreen, like all skincare, isn’t as simple as just ‘slip, slop, slap’. Without any scientific evidence or clinical research to substantiate the claims being made, you’re believing something or someone who may not have any clue what they are actually talking about. In our experience, it’s almost always a reiteration of exactly what the manufacturer has provided in their training manuals and marketing collateral – which is usually bias.

Training and education in the area of cosmetic chemistry and skin science is virtually unheard of in this industry. You’ll get the basics from manufacturer/brand specific training (some much better than others) but this usually doesn’t suffice. It’s the therapists job to go out and educate themselves – finding resources that don’t have a bias and can back up the training with some kind of scientific literature.

Do your research. Know what you are buying into. Do not be an ignorant consumer when it comes to what you’re placing in and on your body. All the information you need is a Google search away. There is a going to be a lot of garbage to sift through but if you take the time, you’ll find credible resources and you’ll be much better off – both immediately and long term.

So, which one is best?

If you’re still reading, you’re probably wondering which one is the best choice.

The answer is simple: whatever best suits ‘you’ as an individual.

There is no clear cut answer to this and from all the research we’ve done, it really comes down to what suits you. Your personal preference.

If your skin can’t tolerate chemical based sunscreens, then perhaps it’s worth questioning ‘why’ before completely writing them off. It may be a sign that something is actually wrong with your skin, not the sunscreen.

Sensitive skin is not a skin type – it’s a skin condition. Perhaps you were born with sensitive skin but this is very rare. It’s far more common that it’s become sensitized through the use or poor quality products, ablative skin treatments and over-exfoliation. With the proper treatments and correct skincare regimen, your sensitive skin can generally be repaired and brought back into a good, non-sensitized state (homeostasis).

What type of sunscreen may also depend on what you’re doing and where you’re going. Chemical sunscreens generally sit much better under makeup and feel a lot lighter. If you’re going swimming, Physical may be a good choice. Experiment and see what best suits you.

More important than ‘chemical vs physical’…

  1. How much you apply and how well you apply it – this makes a huge difference in efficacy. Poor application could result in an SPF30+ becoming more like an SPF5+. Don’t skimp on your sunscreen! You may save a couple of dollars by doing so but the sunburn that follows shortly after will have you regretting your decision. That’s before we even get to the increased risk of pigmentation, accelerated aging and increased risk of skin cancer.
  2. Using a broad spectrum sunscreen that protects from UVA and UVBvery important! Remember, you want to protect yourself against UVA (Aging) and UVB (Burning). Most sunscreens today will do just that but make sure you check the label and confirm it by reading the ingredients.
  3. An SPF rating of at least 30+ – but don’t fall for the marketing hype. You stand to gain about 1% extra protection between SPF30+ and SPF50+ but it could cost you substantially more for that extra 1%. The additional ingredients needed to achieve an SPF50+ also come into play.
  4. Quality over quantity – not all sunscreen is created equal. Avoid sunscreens containing ingredients that are simply not necessary for it to be effective eg. fragrances and parabens. This is where it pays to know your ingredients! Paying $9.95 for a 500ml bottle of SPF50+ probably isn’t going to get you quality.


At the end of the day, physical and chemical sunscreens are like comparing Apple/iOS and Google/Android mobile phones. Both are trying to achieve the same/similar outcome but go about it in a very different way. Some people opt for Apple, others opt for Google – for reasons that are often personal to them.

Hopefully this article helps you make more informed decisions about your sunscreen purchase – a vital purchase all year. Avoid the marketing hype and ridiculous claims being made. Most them are unsubstantiated and based on nothing more than opinions, theories or worse – bias manufacturer marketing.

We’ve linked below to a number of resources we’ve referenced when writing this article.


  1. Chemical vs. Physical Sunscreens: The Science (with video)
  2. “Physical” vs. “chemical” sunscreens and other sunscreen myths
  3. The Absorption Properties of “Physical” Sunscreens
  4. Metal oxide sunscreens protect skin by absorption, not by reflection or scattering
  5. Debunking sunscreen myths part 2