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TikTok’s Serum Hack Made My Makeup Look The Most Natural Ever

Welcome to Beauty In A Tik, where each week we put TikTok's viral beauty hacks and innovative trends to the test.
If you're a makeup wearer, chances are you've googled how to prevent it looking cakey. No matter the price tag, type of coverage or if it was dreamed up by a world-renowned celebrity makeup artist, pretty much all foundation collects in fine lines and pores eventually. While we're no longer averse to skin texture — it's entirely normal and natural — that hasn't stopped TikTok's beauty content creators from inventing new ways to apply foundation for a smooth finish that looks believable.
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Not long ago everyone was into creating their own BB cream, mixing foundation, moisturiser and highlighter (it works and I'm totally convinced). Then came the rainbow contouring hack, which TikTokers claimed would be the only trick you'd ever need for glowing skin all year round. Ahead of spring, when you might choose to pare back the coverage a little, it's all about being your own alchemist and combining your skincare with your makeup for a natural-looking, lightweight result.
I've interviewed countless makeup artists over the years and one thing many of them agree on is that blending skincare and makeup can be a game-changer. I often give my face a spritz with a hydrating toner to help my concealer go on smoothly and I know that makeup artist and Max Factor UK ambassador Caroline Barnes likes to enhance the glow of makeup using a facial oil. Recently, TikTok's beauty enthusiasts have enlisted one very specific skincare product: polyglutamic acid serum.
@kyliekillzzzz Reply to @freya.christine My favorite drugstore moisturizer! AD 🤍 @theinkeylist #theinkeylist ♬ original sound - Kylie Larsen
Beauty pro Kylie Larsen recently went viral for mixing her foundation with The Inkey List's Polyglutamic Acid, £14.49. She said that the trick is "smoothing and hydrating" and makes her skin "look like a filter", going on to explain that those with dry skin would also benefit from a squeeze of the serum while applying foundation. Like all intriguing TikTok hacks, it wasn't long before other makeup wearers decided to give it a go, like Monique aka @skinfiltrator. Her video has also amassed thousands of views and she, too, is sold. "Came out flawless! Felt like butter," she captioned her post.
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@skinfiltrator Trying @Kylie Larsen’s Polyglutamic Acid Makeup Hack using @theinkeylist 👀. #skincarehack #makeuphacks #skincare #theinkeylist #polyglutamicacid ♬ Mesmerised - Bru-C
So what actually is polyglutamic acid? Essentially, it's a souped up version of hyaluronic acid. "Polyglutamic acid, like hyaluronic acid, is a humectant that chemically attracts water molecules," dermatologist Hadley King, MD recently told R29. "It forms a hydrogel film on the surface of the skin that prevents water from evaporating," Dr King continued. "Its occlusive property means that it helps the skin retain moisture." In other words, it keeps hydration under lock and key, which, with the cold weather still clinging on, makes it something of a skincare saviour.
Happily, polyglutamic acid isn't as under the radar as it once was and all manner of beauty brands are jumping on board. Take Boots Ingredients, whose Polyglutamic Acid Serum is just £7. Charlotte Tilbury's new Magic Serum Crystal Elixir, £60, also contains the ingredient, alongside brightening vitamin C and oil-reducing niacinamide. As I tend to splurge on foundation, I decided to opt for the cheaper polyglutamic acid to mix with Charlotte Tilbury's Beautiful Skin Foundation, £34.
@jacquelinekilikita Inspired by @Kylie Larsen and @Monique | Skincare to mix #foundation with #polyglutamicacid for #beautyinatik ♬ Countless - Official Sound Studio
On the back of my hand I pumped a little foundation and followed with an equal amount of polyglutamic acid serum, mixing the two together with the end of my foundation brush. I have to admit that I panicked a little. The two products just didn't want to join forces and ended up a curdled mess! In the name of Beauty In A Tik, I persisted — and actually, I'm quite glad I did. Surprisingly, the concoction applied smoothly over my skin and totally changed the consistency of the foundation, which I find a bit too heavy on its own. I was impressed by both the coverage (lightweight yet substantial enough to cloak my acne scars) and the luminosity. My skin was glowing in all the right places.
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Wary of the initial pilling on the back of my hand, I monitored my makeup throughout the day. Usually, after a good eight hours of wear, I'd have dabbed my under-eyes and smile lines — areas where my foundation always ends up — countless times but I can honestly say that there was no need.
I think this is down to a combination of two things: the polyglutamic acid is so hydrating (supposedly 10 times more so than hyaluronic acid) that it plumped out and ironed away my dehydration lines. Then there's the coverage. I've found that thicker foundation textures can often make pores and creases more visible throughout the day but as the polyglutamic acid diluted my base, I didn't face any of those annoying gripes. A little serum goes a long way, too.
This series has taught me that there are so many TikTok makeup hacks which are useless, like using lube as primer (really) and applying foundation with a jade roller (don't bother). But I can't deny that this one works to make foundation look perfectly natural. This spring, when I want to tone down my makeup coverage, I won't invest in a BB cream or a tinted moisturiser. This is just as good and it has incredible skincare benefits.
Polyglutamic acid wins.
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