K-Secret
SEOUL 1988 GLOW SERUM : NIACINAMIDE 15% + YUJA 30ml
A 30ml brightening serum for uneven tone and dullness, built around a well established tone ingredient and a citrus extract.
No reviews yet30 ml
$166.67 per 100 ml
- Korean-market formula
- Ships from California or direct from Korea
- Korean barcode and batch code intact
- Suited to
- Normal skinCombination skinOily skin
- Helps with
- Uneven skin toneSkin that looks dullThe look of dark marks
In stock. Arrives in 3 to 7 business days
We accept
You’re $100.00 away from free US shipping.
- 30-day returns
- Free US shipping on orders of $100 or more
- Tracked delivery to your door
How it works
This is a thin serum rather than a cream, which is the right shape for tone work: a flat even layer over the whole face is what produces an even result. It goes between the toner and the cream, morning and night, because tone is built by consistency rather than by intensity in any one sitting. The finish is light enough to sit under sunscreen, which matters more here than for most steps, since tone work without that last layer is undone faster than it is built. That is the difference from a strong overnight tone treatment, which does more per use but has to be rationed to a few nights. What you can judge is whether the overall colour reads more even in the same light after a month.
Key benefits
- What it is: a 30ml serum from K-Secret, for the serum step.
- On the ingredient list: Niacinamide, Butylene Glycol, Glycerin, confirmed on this product's own manufacturer list rather than assumed from the category.
- Fits into the routine: delivers a targeted dose of its lead ingredients to the areas that need it most.
- Original Korean Formula: the version sold on Korean shelves, not a US reformulation.
Inside the formula
Inside the formula
What is this serum for?
Uneven tone and dullness, worked on together in a twice daily step rather than an occasional strong one. It is a thin serum over the whole face. You judge it on whether your overall colour reads more even in the same light after about a month of steady use.
Where does it go in my routine?
After cleansing and toning, before moisturizer, morning and night. It lands on damp skin and the cream seals it in. In the morning sunscreen is the last layer, and with any tone product that layer matters more than the rest of the routine combined.
Will it pill under sunscreen?
Rarely, since it is thin, and when it does the cause is usually too much product or not enough settling time. Use a small amount, wait thirty seconds, then the cream, then sunscreen. If it still balls up, cut the dose rather than dropping a layer.
Can I use it with an exfoliating step?
Yes, if you stagger them. Keep this twice daily and give any exfoliating product its own separate evening, so you are not stacking two demanding steps in one sitting. If the skin starts feeling tight, drop this back to once a day for a week.
Is this the Korean-market formula?
Yes. This is the Original Korean Formula 30ml bottle, the same one sold on Korean shelves.
Not on the ingredient list below: fragrance or parfum, denatured or SD alcohol, essential oils, silicones, parabens, sulfate surfactants, mineral oil or petrolatum and added color.
Full INCI (39): Water, Niacinamide, Butylene Glycol, Glycerin, Glycereth-26, 1,2-Hexanediol, Caprylic/Capric Triglyceride, Pentylene Glycol, Macadamia Ternifolia Seed Oil, Ammonium Acryloyldimethyltaurate/VP Copolymer, Polyglyceryl-10 Laurate, Squalane, Panthenol, Hydrogenated Polydecene, Carbomer, Tromethamine, Hydrogenated Lecithin, Polyglyceryl-3 Methylglucose Distearate, Ethylhexylglycerin, Butyrospermum Parkii (Shea) Butter, Adenosine, Sodium Hyaluronate, Gellan Gum, Agar, Sodium Phytate, Beta-Glucan, Citrus Junos Fruit Oil, Glutathione, Helianthus Annuus (Sunflower) Seed Oil, Hydroxydecyl Ubiquinone, Melia Azadirachta Flower Extract, Ocimum Sanctum Leaf Extract, Melia Azadirachta Leaf Extract, Curcuma Longa (Turmeric) Root Extract, Corallina Officinalis Extract, Tranexamic Acid, Xanthan Gum, Tocopherol, Sodium Ascorbyl Phosphate
Ingredient list read from jolse.com on 10 September 2026.
38 of 39 explained
- Water solvent
- Water is the base almost every serum, toner and cream is built on. It dissolves the water-loving ingredients and sets how light the finished texture feels. On an INCI list it is usually first, which only means it is the largest single ingredient by weight.
- Niacinamide active
- Niacinamide is vitamin B3, and it is the most studied active in Korean formulation. It is used at roughly 2 to 5 percent for the look of uneven tone and visible pores, and it is water soluble, stable and comfortable beside almost every other active, which is why it turns up in so many lists.
- Butylene Glycol humectant
- Butylene Glycol is a small glycol that does two jobs at once: it holds water in the top layer of skin and it dissolves plant extracts and actives that plain water cannot. It also thins a formula, which is why watery Korean essences lean on it.
- Glycerin humectant
- Glycerin is the most used humectant in skincare. It draws water into the outer layer of skin and holds it there, and it is one of the very few ingredients whose hydrating effect is settled science rather than marketing. Higher amounts feel tacky, which is why it is usually blended.
- Glycereth-26 humectant
- Glycereth-26 is a modified glycerin that hydrates with far less stickiness than glycerin itself. It is a common way to load water into a formula that has to stay light.
- 1,2-Hexanediol humectant
- 1,2-Hexanediol is a glycol used for two reasons: it holds water like glycerin, and it makes a formula harder for microbes to live in, so less traditional preservative is needed. Korean formulas use it heavily for that second reason.
- Caprylic/Capric Triglyceride emollient
- Caprylic/Capric Triglyceride is the light fraction of coconut oil, with the heavy parts removed. It is the workhorse emollient of modern formulas: it softens skin, dissolves oil-soluble actives and absorbs without the greasy weight of a whole plant oil.
- Pentylene Glycol humectant
- Pentylene Glycol hydrates and, like the other longer-chain glycols, makes a formula less hospitable to microbes so the preservative system can be lighter. It also improves how evenly a product spreads.
- Macadamia Ternifolia Seed Oil emollient
- Macadamia Seed Oil is unusually high in palmitoleic acid, a fatty acid that human sebum also contains, which is why it absorbs faster than most nut oils. It is a cushioning emollient for dry skin.
- Ammonium Acryloyldimethyltaurate/VP Copolymer thickener
- This is a synthetic thickener that gels quickly and holds an emulsion stable across a wide pH range. It gives a light, non-tacky body.
- Polyglyceryl-10 Laurate emulsifier
- Polyglyceryl-10 Laurate is a sugar-derived emulsifier and solubiliser, mild enough to be a standard choice in Korean essences. It dissolves small amounts of oil into water without any tightening feel.
- Squalane emollient
- Squalane is the stable, saturated version of squalene, a lipid human skin already makes. It is a light emollient that absorbs quickly, does not oxidise, and is one of the few oils widely considered safe for blemish-prone skin. Most cosmetic squalane is now from sugarcane or olive rather than shark.
26 more explained
- Panthenol humectant
- Panthenol is pro-vitamin B5: skin converts it to pantothenic acid. It is a humectant that holds water and leaves skin feeling soft and less tight, and it is one of the ingredients formulators reach for when a formula also contains something harsh.
- Hydrogenated Polydecene emollient
- Hydrogenated Polydecene is a synthetic hydrocarbon emollient used in place of mineral oil. It is stable, has no scent, and gives a cushioned slip without oxidising.
- Carbomer thickener
- Carbomer is a synthetic polymer that only gels once a base neutralises it, which is why arginine or tromethamine sits nearby on the list. It gives the clear, non-stringy gel texture a xanthan formula cannot reach.
- Tromethamine pH adjuster
- Tromethamine neutralises acidic thickeners such as carbomer so they gel, and holds a formula near skin-friendly pH. It is used at a fraction of a percent.
- Hydrogenated Lecithin emulsifier
- Hydrogenated Lecithin is lecithin with its unsaturated bonds filled in, which makes it far more stable. It emulsifies and is the standard shell for the liposomes that carry actives into the outer layer of skin.
- Polyglyceryl-3 Methylglucose Distearate emulsifier
- Polyglyceryl-3 Methylglucose Distearate is a sugar-derived emulsifier known for a light, non-soapy feel. It builds gel-creams that do not read as rich.
- Ethylhexylglycerin preservative booster
- Ethylhexylglycerin softens skin and boosts a preservative system, which is why it is nearly always sitting beside phenoxyethanol or 1,2-hexanediol. It also cuts down the odour bacteria produce, so it turns up in deodorising products.
- Butyrospermum Parkii (Shea) Butter emollient
- Shea Butter is the fat pressed from the shea nut, rich in oleic and stearic acids and unsaponifiable plant sterols. It is a heavy emollient and partial occlusive, which is why it sits in balms and night creams rather than in essences.
- Adenosine active
- Adenosine is a nucleoside that Korea's own cosmetic authority recognises as a wrinkle-care functional ingredient, which is why it appears on so many Korean lists at a low level. It is used for the look of fine lines and is stable and well tolerated.
- Sodium Hyaluronate humectant
- Sodium Hyaluronate is the salt of hyaluronic acid, and it is what most products labelled hyaluronic actually contain. The salt dissolves more readily and the molecule is smaller, so it sits in the outer layer of skin rather than only on top of it.
- Gellan Gum thickener
- Gellan Gum is a fermentation-derived polysaccharide that sets a clear, brittle gel at very low levels. It is used to suspend particles without thickening the liquid much.
- Agar thickener
- Agar is a seaweed polysaccharide that sets into a firm gel. It is the gelling agent behind jelly masks and thick sleeping packs.
- Sodium Phytate chelator
- Sodium Phytate is a rice-derived chelator used in place of EDTA. It ties up trace metals so the formula stays stable and its colour and scent hold.
- Beta-Glucan polysaccharide
- Beta-Glucan is a polysaccharide from oats or yeast. It holds a large amount of water, forms a soothing film, and is one of the ingredients formulators reach for in products aimed at reactive skin.
- Citrus Junos Fruit Oil fragrance component
- Yuzu fruit oil, pressed from the peel of the East Asian citrus. It is high in limonene and carries the sharp yuzu aroma, so it is used to scent a formula.
- Glutathione antioxidant
- Glutathione is a small peptide the body uses as one of its main antioxidants. In skincare it is used as an antioxidant and for the look of dullness; it is unstable in water, so formulas that carry it are usually built around protecting it.
- Helianthus Annuus (Sunflower) Seed Oil emollient
- Sunflower Seed Oil is high in linoleic acid, the fatty acid dry and blemish-prone skin is often short of. It is a light, non-fragrant emollient and one of the better tolerated plant oils.
- Hydroxydecyl Ubiquinone antioxidant
- Hydroxydecyl Ubiquinone is idebenone, a synthetic relative of coenzyme Q10 made to be more stable and more soluble than the natural molecule.
- Melia Azadirachta Flower Extract plant extract
- Melia Azadirachta is neem. Its leaf and flower extracts are long-standing Ayurvedic ingredients, and Korean formulas use them in products aimed at the look of congested, blemish-prone skin.
- Ocimum Sanctum Leaf Extract plant extract
- Ocimum Sanctum is holy basil, or tulsi. Its leaf extract carries plant antioxidants and is used in formulas built for the look of stressed, reactive skin.
- Curcuma Longa (Turmeric) Root Extract plant extract
- Turmeric Root Extract carries curcuminoids, well studied plant antioxidants. It is used for the look of dullness and uneven tone, and it tints a formula faintly yellow.
- Corallina Officinalis Extract plant extract
- Corallina Officinalis is coral seaweed, which holds calcium and magnesium in its structure. Its extract is used as a mineral-rich conditioning ingredient.
- Tranexamic Acid active
- Tranexamic Acid is a synthetic amino acid derivative used for the look of stubborn discolouration and post-blemish marks. It is water soluble, stable and comfortable next to niacinamide, which is how it is usually paired.
- Xanthan Gum thickener
- Xanthan Gum is a polysaccharide made by fermenting sugar. It thickens a watery formula into a gel and holds the whole thing in suspension so nothing separates. Too much of it and a serum turns stringy, which is why it appears in fractions of a percent.
- Tocopherol antioxidant
- Tocopherol is vitamin E. It is an oil-soluble antioxidant that protects the oils in a formula from going rancid and works on skin as an emollient, and it is regularly paired with vitamin C because each keeps the other going for longer.
- Sodium Ascorbyl Phosphate antioxidant
- Sodium Ascorbyl Phosphate is a water-soluble, stable vitamin C salt. It works at near-neutral pH, so it appears in formulas aimed at skin that pure ascorbic acid leaves stinging.
- Market
- Korean market, the version sold in Korea
- EAN (barcode)
- 8809695240621
- Made in
- Republic of Korea
- Volume
- 30 ml
- Category
- Serum & Ampoule
- Actives
- Adenosine, Beta-Glucan, Glutathione, Niacinamide, Panthenol, Shea Butter, Sodium Hyaluronate, Squalane, Tranexamic Acid
- Ships from
- California or Korea
Orders ship from California or direct from Korea with tracked delivery to your door, and both routes carry the same Korean-market release. Shipping is free on orders of $100 or more. Returns are accepted for 30 days, by mail.
We split shipments free, so one out-of-stock item never holds up the rest of your order.
Where this unit came from
- 1Seoul
Bought as Korean-market stock - 2Barcode
Listed against the Korean barcode on its box - 3California or Korea
Ships to you from either, as the same Korean-market release
We stock the version of a formula that is sold in Korea, not the release a brand prepares for another market under the same name. The barcode in the specification above is the Korean-market one and it is printed on the box you receive.
Every unit keeps its original barcode and batch code intact, so the unit in your hands can be checked against the brand’s own records.
Every order ships from California or direct from Korea, and returns run for 30 days.
Every claim on this page traces to the unit in the box, the barcode, the batch code and the price you can read for yourself.
How to use
- Apply after the toner while the skin is still damp so a thin layer covers the face in one pass.
- Press it over the whole face rather than only the darker patches, since even tone needs full coverage.
- Follow with a cream to hold it in place, and with sunscreen as the final morning step.
- Do not skip the morning sunscreen, since tone work without that last layer is undone faster than it is built.
Worth knowing
- Wear sunscreen every morning alongside it, because a tone routine assumes that layer is going on.
- Build up from every other morning if your skin reacts easily to new leave-on products.
Complete the routine
- This itemK-Secret SEOUL 1988 GLOW SERUM : NIACINAMIDE 15% + YUJA 30ml$50.00
- Seal the routine in as the last stepK-SECRET SEOUL 1988 Cream : Snail Mucin 93% + Rice 100ml$50.00
- From the same Korean-market lineK-Secret Advanced Regenerating Eye Gel Patches$19.99
Total for 3 items$119.99
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K-SECRET SEOUL 1988 GLOW SERUM : NIACINAMIDE 15% + YUJA 30ml
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K-Secret, Korean-market original
A 30ml brightening serum for uneven, dull looking skin, stocked in the Original Korean Formula.
Verify your unit when it arrives
Verify your unit when it arrives
Korean-market stock with the original barcode and batch code intact, exactly as it left Korea.
On the unit itself
- The Korean-market barcode, unaltered from the retail package.
- The manufacturer’s batch code, exactly as the maker printed it.
정품Genuine article, Korean-market stock
What professionals say
What professionals say
What skin-care professionals say about skin care, quoted from the medical sources linked beside each.
Your skin barrier is basically your outer layer of the skin.
Melissa Piliang, MDDermatologist, Cleveland Clinic Pretty much every step of a Korean skin care routine is going to have some component of hydration.
Alok Vij, MDDermatologist, Cleveland Clinic
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