isoi's description of the Heartleaf Pore Mask includes two numbers that are worth reading carefully: heartleaf extract at 10,000 ppm and PHA at 500 ppm. The first is a respectable dose for a sheet mask, one percent of a well-liked soothing botanical. The second is much smaller. Five hundred parts per million is 0.05 percent, and polyhydroxy acids like gluconolactone generally need several percent to exfoliate. That small number is the key to understanding this mask. Despite the word pore in the name, it works through calming and hydration, not by clearing pores.
That is not a criticism. For many people with oily, congested skin that also reacts easily, a gentle, hydrating mask is more useful than another exfoliant. The formula is thoughtfully simple. After water come butylene glycol, glycerin and 1,2-hexanediol, then houttuynia cordata extract, the Jeju heartleaf of the name, in fifth place. Polyglycerin-3 and trehalose add humectancy, panthenol and allantoin soothe, and adenosine offers a light anti-ageing extra. The list ends with eight forms of hyaluronic acid: hydrolyzed hyaluronic acid, sodium hyaluronate, hydroxypropyltrimonium hyaluronate, sodium acetylated hyaluronate, hyaluronic acid, hydrolyzed sodium hyaluronate, a crosspolymer and potassium hyaluronate. The marketing mentions ten types, but eight appear in the published list. There is no fragrance, no alcohol and no oil.
Heartleaf has become one of Korean skincare's most popular calming ingredients, largely because it suits oily, acne-prone skin that also flushes or stings easily. Its flavonoids, including quercetin derivatives, have anti-inflammatory and antioxidant activity in laboratory studies. At one percent in an occlusive sheet, it contributes a calming effect that many people with reactive, congested skin appreciate.
In use, the thin sheet is well soaked with a light, slightly gel-like essence. It feels cool and comfortable, with no sting, which is exactly what you want from a mask marketed for sensitive skin. After ten to twenty minutes, skin looks calmer and more even, and pores on the cheeks and nose look softer. That softening comes from hydration: well-hydrated skin reflects light more evenly and plumps slightly around each pore opening, making pores less obvious. The effect lasts several hours, longer if a light moisturiser goes on top.
The brand cites its own four-week testing showing improvements in pore depth, count and area. Those figures come from company-run studies and have not been independently published, so they are best read as marketing. Pore size is largely determined by genetics, oil production and skin elasticity, and no sheet mask changes it permanently. For real pore and blackhead care, a leave-on salicylic acid or retinoid used on other nights is the more effective partner, and this mask fits comfortably alongside either because it adds no irritation.
The mask is a particularly good choice in a few situations: after a day in the sun or wind, when skin feels hot and tight; alongside acne treatments that leave skin dry and reactive; or simply as a calming weekly ritual for combination skin. Because it is fragrance-free and alcohol-free, it is one of the safer sheet masks for sensitive skin.
Getting the most from each sheet is straightforward. Apply it to skin that is still slightly damp from toner, which helps the essence spread evenly. Smooth the sheet firmly around the nose, where it tends to lift, because that is where most people want the pore-smoothing effect. Remove it before it dries completely, around the twenty-minute mark at most, since a drying sheet can start to pull water back out of the skin. Then pat the leftover essence into the face, neck and backs of the hands rather than wasting it.
It also helps to think about how the mask fits a weekly routine for oily, congested skin. A sensible pattern is a gentle cleanser morning and night, a leave-on salicylic acid two or three evenings a week, a light moisturiser and sunscreen daily, and this mask on the evenings in between, when skin needs a break from actives. That combination addresses clogged pores directly with the BHA while the mask keeps skin calm and hydrated, reducing the chance of the dryness and redness that often follow acne treatments.
Chilling a pouch in the fridge before use adds a pleasant cooling effect, which is especially welcome in summer or after exercise, and can make flushed, overheated skin look calmer faster.
On value, StyleKorean lists a pack of five at about ten and a half dollars, roughly two dollars a sheet, which is reasonable for a well-formulated Korean mask. Single sheets are also sold.
isoi, founded in 2006 and known mainly for its Bulgarian rose products, launched this mask in 2025. The brand publishes its full ingredient list and declared doses, which is commendable. User reviews are still scarce, and no independent testing exists.
The verdict: a well-made, gentle hydration mask with a real dose of heartleaf and an honest, if small, dose of PHA. Buy it for calm, comfortable, smoother-looking skin, not for exfoliation.
