Today’s video is on one of the more commonly asked questions I get about sunscreen. You put your sunscreen on in the morning, apply your makeup over it… but you’re meant to reapply it every 2 hours. So how do you reapply it without messing up your makeup? And do you really need to reapply it?

Here’s the video on YouTube, including a demo of how I do it and some cool footage of sunscreen sprays – scroll down for the text version.

Why do you need to reapply sunscreen?

If you look on your sunscreen, you’ll notice that it says to reapply regularly, usually every 2 hours. That’s because sunscreen gets less effective over time.

Firstly, sunscreen comes off if you brush against it – with your hands, your clothes and your hair. The less sunscreen you have on your skin, the less protection you get.

Related post: What Does SPF Mean? The Science of Sunscreen

Secondly, when you first apply sunscreen, if you apply enough, it’ll form an even, continuous film that protects your skin. But over time, the sunscreen film breaks up as it interacts with the oil and water that your skin produces throughout the day. It’s worse if there’s any heavy sweating. The layer also breaks up and clumps into bits as your skin moves around – when you talk and eat and yawn.

These photos aren’t sunscreen but foundation – it’s another product that’s designed to stay on your skin in an even film for as long as possible, so it uses some of the same technologies, and it’s much easier to see.

The microscope photo on the left is right after application, and the photo on the right is after a few hours. You can see that it clumps up and moves around, migrating into pores and creases on your skin over time.

Related post: Foundation Clumping Science, and How to Fix It (with Video)

The sunscreen film also gets thinner as time goes on, because it evaporates and is absorbed into the skin. This changes the absorption properties of the film for the worse.

The final reason, but probably the one that most people know, is that some older organic “chemical” sunscreens aren’t photostable. This means they break down after absorbing too much UV.

Sunscreens these days are usually formulated to be photostable – they use photostable organic or inorganic filters, or they use photounstable filters in ways that increase their photostability. That means they don’t have this specific problem, but they’re still affected by the first two issues, so they’ll still get less effective over time.

Related post: Chemical vs Physical Sunscreens: The Science (with video)

So after you apply sunscreen, the film wears down and you end up with less and less sun protection as time goes on.

But how much less?

How much protection is left after 2 hours?

Unfortunately there isn’t that much info on how long sunscreen lasts on your skin if you aren’t moving around much. There’s only one study directly on this topic so far that I could find (thanks to Kind of Stephen).

20 people applied 2 mg/cm² of sunscreen with a dye in it, so the researchers could easily photograph where the sunscreen went every 2 hours. They didn’t use any other products on their face, and they were allowed outside for up to an hour.

Here’s a graph of what happened (purple line is the average, grey shaded area is the range):

After 2 hours, there was an average of 16% less dye. After 4 hours it was 7% less than that, and then after 8 hours it was another 4.5% less – a total of almost 30% less dye, which means probably somewhere in the region of 30% less sunscreen coverage.

We can’t confidently say that these results will be the same for every sunscreen since different sunscreens have different lasting power – water resistant sunscreens stay on skin for longer even when they’re being disturbed, and some chemical sunscreens do absorb into the top layers of skin which helps them last. But it’s likely that there’s still a significant amount of protection on your skin at the end of the day from most sunscreens, if you don’t move around much.

As an indication, if you take 30% away, SPF 50 becomes SPF 35, SPF 30 becomes SPF 21, and SPF 15 becomes SPF 10 (SPF varies approximately linearly with the amount of sunscreen on your skin). The higher the SPF you start off with, the more likely it is that you’ll have more protection left at the end of the day.

But is this protection enough?

Like I said in my post on wearing sunscreen indoors, how much protection you need depends on both how much UV you’re exposed to, and how concerned you are about the effects of UV (the main issues for most people are skin cancer, wrinkles and hyperpigmentation).

If you’re reapplying sunscreen on top of makeup, you’ll have to mess up your makeup to some extent, or apply less sunscreen, or apply less evenly. There isn’t really a way to avoid this compromise.

I’ve divided my approach to reapplying sunscreen into 3 general situations which work for me:

Situation 1: Minimal Sun

This is if I’m not going to get much sun – for example, if I go to work in the morning, get mostly indirect sun exposure within the first 2 hours, then at the end of the day I go home and most of my commute is in the dark.

In this sort of situation, I don’t reapply. I rely on my residual sunscreen to get me through and try to avoid sun exposure – nothing too extreme, but I’ll walk on the shady side of the street and I’ll sit away from the window on the train.

This is most days, and I’ve found that for me, with the sunscreens I’m using and my skin type and my sun exposure situation, that’s enough. My freckles have lightened and post-inflammatory hyperpigmentation fades quickly, which I think is a good sign that I’m getting significant sun protection.

Related post: Video: My Top 6 Favourite Sunscreens

Situation 2: Lots of Sun

Let’s go to the other extreme: when I get a lot of unavoidable sun exposure.

For example, I have breakfast in the morning with a friend, then we go on a 4 hour walk around some nice beaches. I know I’m going to get a ton of sun exposure no matter how hard I try, and I’m probably going to sweat a whole bunch, and I really need to be applying my sunscreen every 2 hours or I’m going to get sunburnt.

In this situation, I put on water resistant sunscreen and keep my makeup simple – for example, tinted moisturiser and blush, or maybe even only concealer in the key areas. I don’t even bother with products that need to stay on specific areas of my face, the priority is sun protection. Then every 2 hours, I reapply water resistant sunscreen and that minimal makeup if necessary.

When reapplying, you don’t need to wash off your sunscreen or anything – you can just reapply sunscreen on top. If there’s dirt on your face or the layer is getting too thick, you can use a makeup wipe to get some off your face (especially if there’s dirt, you don’t want to be exfoliating away at your skin every time you reapply!). If you break out from repeated reapplications of a sunscreen that’s usually fine, it might also be worth removing some with a makeup wipe.

I’ll also wear a hat and sun-protective clothing, and reapply sunscreen on my body regularly as well.

Situation 3: Some Sun

Then there’s the in-between situation, which I think is the one most people are wondering about – where you want to look good with most of your makeup intact, but you also need to reapply a decent amount of sunscreen.

For example, I’m working in the office, but then I go for a nice long walk for lunch, and then I have a sunny afternoon ride on the train to go home and the sun is coming in horizontally through the train windows. In this situation I’ll have my standard amount of makeup and the sunscreen I applied in the morning, but I’d want to to reapply sunscreen on top.

The most important thing to remember is that sun protection scales with the amount you apply. On average, this is pretty much linear. If you apply around ¼ teaspoon on your face, you’ll get the protection on the label, but if you apply half of that, then you’ll get half the protection. So it’s a matter of getting as much sunscreening product as possible onto your face in an even layer, while disturbing the makeup that’s already on your face as little as possible.

Related video: How Much Sunscreen Do You Need For Your Face?

Which product should I use for reapplication?

Let’s talk about the different products you might use for reapplication, starting with the ones I wouldn’t recommend:

Foundation

There probably isn’t enough protection in SPF-rated foundation on its own. According to a 2006 study, an average application of liquid foundation is 0.54 g, although there was a lot of variation.

For that average 0.54 g of foundation on a 400 cm² face, you’ll get these actual SPFs:

• SPF 50 → SPF 34
• SPF 30 → SPF 20
• SPF 15 → SPF 10

I use one pump of my foundation from The Body Shop which works out to be 0.2 g. With that amount, you’ll get these actual SPFs:

• SPF 50 → SPF 12.5
• SPF 30 → SPF 7.5
• SPF 15 → SPF 3.8

Powders

Powders are even worse. The Cosmetic, Toiletry, and Fragrance Association did three studies on 10 000 women in the US in the 80s and found that an average application of face powder was 85 milligrams. On a 400 cm² face:

• SPF 50 → SPF 5.5
• SPF 30 → SPF 3.2
• SPF 15 → SPF 1.6

There’s also the issue that powders probably don’t cover your face in a continuous even layer.

It’s possible that there are technologies in powder sunscreens that make them apply more densely than regular powders, so I asked a bunch of powder sunscreen companies if they had data on the expected protection with a typical application of their products. The answers I got back were really variable, and as much as I want convenient powder sunscreen to be a thing, I didn’t find the data all that compelling.

Overall, it just seems really unlikely that people can apply

1. enough powder
2. reliably every time
3. in an even continuous layer

to get significant coverage, even as a top up method.

The most promising data I got was from Colorescience. Their specially treated powder is designed to stick to skin better for a greater application amount, and it’s actually 80 minutes water resistant. This rating is significant because it means it was applied on people’s skin, then they sat in a jacuzzi for 4 sessions of 20 minutes before the UV protection that was left was remeasured to be SPF 50. After one of these tests the powder left on the skin of 3 subjects was measured – there was an average of 0.542 mg/cm² of product remaining.

This probably doesn’t happen with most powders – an average application of 85 mg would give less than half of this – so I was pretty impressed. I think it works well because their formula has a really high percentage of minerals in it, along with the special coating.

The bad news: to get this result they applied 2 mg/cm² of powder onto the skin, patted it into an even layer, then left it for 15 minutes before going into the water. So application-wise, it seems pretty unrealistic.

Even if we assume that the extra powder wasn’t necessary, 0.542 mg/cm² is also quite a lot of product – about 0.22 g for a full face application.

According to a Colorescience study, to get that much product out of the brush (note: not necessarily onto your face), you have to swirl the brush around your face for a full 60 seconds, priming the brush 4 times in the process (this involves tapping it sharply on the table a few times and flicking it until it produces a puff of powder). 60 seconds is 6 Happy Birthdays, in the current standard unit of time – again, I think that’s unrealistic, especially since the instructions don’t tell you to prime the brush that much, it’s hard to see how much powder actually comes out of the brush, and the brush dispenser mechanism doesn’t dispense powder at a consistent rate.

Plus with powder sunscreens, a lot of them come in very small pack sizes – 2.5 to 7 g – so the cost adds up pretty quickly.

As far as powders go, I think Colorescience is probably your best bet, and in general if they’re water-resistant I think they’ll perform better since they go through that jacuzzi test before their SPF is measured. But other formats are probably more reliable and more likely to be effective.

So there’s only really two reliable options that I’ve come across so far:

Sprays

Spray sunscreens are an option that I’ve warmed up to since trying out a few in the past year. The evenness of coverage can actually be a lot better than creams since they tend to have a low viscosity – they’re runny enough to get into the valleys in your skin. Even though there’s droplets, if you apply enough layers you get pretty decent coverage.

Again, the main issue with sprays is with the amount you apply. It’s easy to underapply if you just mist the sunscreen on like a setting spray. Instead, I’d recommend applying a bunch of thin layers and letting them dry in between so your makeup doesn’t run.

You can spray your spray into a quarter teaspoon measure to work out how many sprays you need to get a reasonable amount of sunscreen. With the three I tried (Neutrogena Ultra Sheer Face Mist SPF 55, Soleil Toujours SPF 30 Set + Protect Micro Mist, Bioderma Hydrabio Eau de Soin SPF 30), I found that it was between 4 and 9 full pumps to get a quarter teaspoon (I recommend measuring your own ones, in case your packaging or your spraying method is slightly different).

There’s an additional issue with aerosol sunscreens – these are the ones in pressurised metal cans which contain propellant (they continuously spray when you hold the top down). A test from Choice magazine found that only 40-60% of the sprayed product was sunscreen, with the rest being propellant. Since the SPF test is performed before adding the propellant, you’d actually need to apply a fair bit more to get the labelled SPF protection.

A few extra tips for using sprays:

• Be careful not to inhale spray sunscreen (it’s not good for you, especially if it’s a mineral sunscreen). Hold your breath, apply a layer, then walk a few steps out of the cloud before breathing again.
• Be careful when applying sprays outdoors so the wind doesn’t blow it into your eyes or just… away (that wastage!).

Lotion

The other option that I think works really well is applying your regular sunscreen lotion over your makeup with a cushion puff (I rescued this one from a Shu Uemura foundation cushion, but you can buy cheap ones online for less than $2 each).

James and Robert Welsh recently did a video about how to apply sunscreen over makeup, and they recommended cushion compacts as a good compromise between sun protection and not messing up your makeup. But, as they mentioned, these tend to use mineral filters which can give a white cast.

So what I prefer doing is using a cushion applicator to pat on my regular sunscreen. I talked about this in my sunscreen and makeup video – I first read about this technique in the Asian skincare community about 6 years ago. Some people even buy an empty cushion container to put their sunscreen in, but I don’t think it’s necessary. Cushion puff applicators are usually no more than a couple of dollars each.

There are a lot of things I love about cushion applicators. They’re a lot thinner than regular beauty sponges, so they don’t soak up as much sunscreen (again, the application amount matters). They’re easy to carry around (you can put one in a ziplock bag to keep it clean), and you can fold it to get it into tight areas around your nose and eyes.

The demonstration of my reapplication in the video starts at around 13:10. I find that this method works best with a lightweight silicone-based sunscreen – I’m using Klairs Soft Airy UV Essence in the video (I reviewed it earlier here).

The trickiest bit is not transferring any of the coloured makeup to the parts of your face that don’t have colour. I start with a couple of layers on the skin coloured bits, then move onto the coloured sections. I don’t think it’s possible to reapply over eyeshadow without ruining it – maybe don’t wear eyeshadow, or reapply your eyeshadow afterwards (using a single colour might be less annoying).

Whatever reapplication method you’re using, it’s a good idea to check if the ingredients are compatible. Some ingredients can break down others, but the impact is probably pretty low (there’s more about this in the free sample chapter of my eBook). When in doubt, you can always just reapply the same sunscreen you used in the morning.

If you have a sunscreen reapplication hack I haven’t mentioned, share it in the comments!

References

(There’s a lot of stuff that I’ve mentioned in older videos and posts – the references are in those!)

Rungananchai C et al., Sunscreen application to the face persists beyond 2 hours in indoor workers: an open-label trial, J Dermatolog Treat 2019, 30, 483-486. DOI: 10.1080/09546634.2018.1530440

Loretz L et al., Exposure data for personal care products: hairspray, spray perfume, liquid foundation, shampoo, body wash, and solid antiperspirant, Food Chem Toxicol 2006, 44, 2008-2018. DOI: 10.1016/j.fct.2006.06.029

US EPA, Chapter 17 – Consumer products, in Exposure Factors Handbook 2011.

Colorescience submission to the FDA (esp Attachments 2, 6, 7, 8): https://www.regulations.gov/document?D=FDA-1978-N-0018-11412