Every skin type should and can use sunscreen. There is absolutely zero point in investing in expensive serums, moisturisers and cleansers etc, if you’re not going to protect your skin from damaging UV rays.

So, let’s delve in to everything you need to know about SPF, together!  ☀️🌤

So, What Are UV Rays?

I’m glad you asked…

UV stands for ultraviolet radiation. Light from the sun is the number one source of UV radiation. However, you can also experience UV radiation from artificial sources such as tanning beds, for example.

UV radiation can lead to sunburn (erythema), premature ageing of the skin (wrinkles, dryness, sun spots etc.), eye problems, a weakened immune system and of course, skin cancer. You will also see, once exposed to UV radiation, the skin’s adaptive mechanisms at play. These show visibly as a tan (increased melanin production) and less visibly, as thickening of the outermost layers of the skin. These are both signs that your DNA is damaged and that you body is trying to stop UV radiation from reaching the deeper layers of the skin.

There are 3 types of UV radiation:

  • UVA: these rays are what causes cells to age and can cause indirect damage to cell’s DNA. UVA radiation is linked to long-term skin damage such as wrinkles and are thought to play a role in some skin cancers
  • UVB: these rays are the main ones that cause skin to burn. They can damage a cell’s DNA directly and are thought to cause most skin cancers.
  • UVC: these rays react with the ozone and so don’t reach our Earth’s surface. However, they can come from man-made sources such as UV sanitising bulbs and welding torches.

The World Health Organisation has stated that UV light is a proven carcinogen (has cancer causing potential). Regardless of your skin colour, everyone should be using an SPF to protect their skin from UV damage. 

As well as SPF, hats, sunglasses, long-sleeves and umbrellas are all ways that can help protect you from the sun’s rays 😎.

Ok, But What’s The Difference Between Sunscreen, SPF and Broad-Spectrum SPF?!


The actual lotion or formula that you are applying to your skin (think of the white thick stuff your mum plastered on you as a child!).


Means sun protection factor and is a scientific measure of how long sunscreen will protect you from UVB rays ONLY (the ones that cause you to burn). For example, using an SPF of 30 means it takes you 30 minutes longer to burn compared to when you’re not wearing it, SPF 50 = 50 minutes longer etc. These numbers have been found by careful lab testing. 

Broad-Spectrum SPF

This is the one that protects you from both UVB and UVA radiation. So, you’re getting protection from UVB’s burning effects and UVA’s ageing effects.


You may have also seen on some sunscreens the letters PA followed by plus signs (PA+, PA++, PA+++, and PA++++). This is a rating system developed in Japan that represents how much UVA protection the product offers. The more plus signs, the better you are protected from UVA radiation (the one that causes ageing). 

However, the PA rating is not related to time like SPF numbers are, which causes much confusion as to what the PA+ actually means. In other words, no one knows how long the PA rating lasts from person to person in real-world use.

Sun Protection Ratings:


6-14 = Low protection
15-29 = Medium protection
30-50 = High protection
50+ = Very high protection

*the numbers relate to the time it takes your skin to burn, in minutes, compared to when you’re not wearing sunscreen.


PA+ = Some UVA protection
PA++ = Moderate UVA protection
PA+++ = High UVA protection
PA++++ = Extremely High UVA protection

*not related to time

All of the above are chemical sunscreens

How Does SPF Actually Work?

So, SPF can work in one of two ways; by either blocking out the sun’s rays with an opaque coating on the skin (physical or ‘natural’ sunscreens). Or by causing a chemical reaction, where the UV rays are absorbed and changed into another type of energy (chemical sunscreens).

So What’s The Difference Between Physical & Chemical Sunscreens?

Physical Sunscreens: these contain mineral ingredients like titanium oxide and zinc oxide. These ingredients act to reflect the UV light before it penetrates the skin and causes damage. It is this form of sunscreen that is often thicker in texture, more difficult to spread and can give the appearance of a white or grey cast on the skin. 

Chemical Sunscreens: often made of ingredients such as oxybenzone, avobenzone, octisalate, octocrylene, homosalate, or octinoxate. These ingredients act to absorb UV rays before they damage the skin. They are lighter in consistency, easier to spread and don’t produce a white-cast on the skin.

Is One Better Than The Other?

Well, I guess from the above you would assume that chemical sunscreens sound like the better choice. However, some chemical sunscreens have been found to cause allergic reactions and irritation in sensitive skin types.

On the other hand, physical sunscreens are thicker and heavier and so may not be the best choice for oily and acne-prone skin. However, it is these sunscreens that are helpful to show you where you have applied sunscreen and what areas may have been missed.

So, there are pro and cons to both but like many skincare products, it comes down to a degree of trial and error as to which ones you prefer (and obviously what skin type you have).

You don’t need to wear both but you will see some sunscreens on the market that contain physical and chemical SPF ingredients, if that’s what you prefer.

How Much Sunscreen Should I Actually Apply?

The golden question. 

To achieve the SPF reflected on a bottle of sunscreen, you should use approximately two milligrams of sunscreen per square centimeter of skin. That’s equivalent to 6 teaspoons (or 2 tablespoons) for an average adult body.

Now most of us definitely don’t use enough! I, for one, was sure I wasn’t using enough and there’s no way I could figure out how much of the two tablespoons should be assigned to my face! So, in that case, I’ve been using the ‘two-finger method’… keep it clean please people!

According to a letter in the British Medical Journal, the method above is enough to cover your ‘head, face and neck’ and then you would do the same for each part of your body (see the letter for more info on the body!).

I have been doing this and find it’s a good amount for my face/neck/chest and of course, my ears!

Do I Need To Reapply It Throughout The Day?

Ideally, you need to be reapplying your sunscreen every 2 hours or more if you’re in and out of water!

But let’s be real, who does that? Apart from when you’re actually outside sunbathing/on holiday. For most of us, at work, going about our day, we have makeup on. This makes reapplying sunscreen near impossible because who has the time to take off their makeup, put on sunscreen and then redo their makeup?! Please comment below if you do this!

However, researching for this blog led me to 2 ways that would allow us to reapply SPF over makeup;

  1. Use a mist sunscreen like this one by Kate Somerville
  2. Use a mineral SPF powder like this one

Genius! I’m definitely going to get some of the mist, I think it would be super refreshing on a hot day! 💦

Do I Really Need Sunscreen Every Day, What If I’m In The House All Day?

Well, most windows will block UVB rays (the one that makes you burn) but most of them won’t block UVA rays (the ones that make you age). So, if you want to slow that process down, wear sunscreen! Especially, if like me, you sit in front of a window all day on your laptop!

What Age Should I Start Using Sunscreen?

If you haven’t been using sunscreen from birth, you’re late. I’m joking but seriously, everyone, of any age, should be using an SPF of at least 30. Plus, every day, in my opinion.

I’m so ashamed to admit that I didn’t start using any daily until I was 27. If anything I avoided it in every way possible because I thought every single brand would give me spots 🤦🏼‍♀️.

I literally shiver now at the thought of the damage that I have done! But it’s ok we got that vitamin C, retinoids and niacinamide to reverse previous damage!

Some SPF Myths?

Let’s bust some myths!

  • Any SPF will do – no. You want a broad-spectrum SPF so that you’re protected from both UVA and UVB rays. Ideally, you also want a high SPF rating, i.e 50+.
  • SPF accumulates – wrong. Even if your moisturiser, foundation and sunscreen contain SPF, you’re only wearing the one with the highest rating. For example, if your moisturiser is SPF 30, your foundation is SPF 20 and your sunscreen is 50, you’re only wearing factor 50. It’s not a case of 30+20+50 = SPF100. 
  • Sunscreen can be waterproof – no sunscreen is waterproof. They can only be listed as ‘water-resistant’, legally.
  • Darker skins don’t need SPF – whilst it’s true that darker skin types are not as vulnerable to UV light (due to their natural, built-in SPF of approx. 13.3), they still need SPF to protect from the damage that UV rays can cause.
  • There’s SPF in my foundation so I don’t need it – SPF should be treated as its own separate product. SPF in makeup or moisturiser is not sufficient enough and may not cover you for both UVA and UVB rays. Like you have your separate skincare products to address separate skincare concerns, your SPF is for the concern of SPF damage so should have it’s own dedicated application to your face.

Lastly, remember that your sunscreen should always be applied last, after moisturising, and before makeup! That counts for both mineral and chemical sunscreens.

Feel all clued up on your sunscreens now and why you should be using them, every day?! I hope so! 🤞🏼

We can all enjoy the glorious sunshine but just be sensible and diligent with your sunscreen use and reapplication! It’s for the benefit of your skin and your health.

Subscribe here to find out what my next blog post will be about! Until then, leave me a comment below, I’ll always get back to you!

Love & Knowledge



P.S. You may also want to take a look at my own personal skincare journey & why I began Skin Acid Trip, here ❤. Or perhaps brush up on some other ingredients via the ‘Ingredients Spotlight’ category!

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  1. Skinbytashx 12/08/2020 at 17:06

    I love this 🥰😍

    1. Samantha 12/08/2020 at 17:08

      ❤️❤️❤️ Thank you Tash!! xxxxxx


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