Heimish RX Amino Keratin Heat Protecting Leave In Treatment Review

There is a particular kind of honesty that Korean labelling rules produce, and this tube is a fine example of it. Hydrolysed keratin: 200 ppm. Glycine: 24 ppm. Cysteine, histidine, methionine: 1 ppm each. Heimish has printed the concentration of every amino acid in its Amino Keratin leave-in, and the numbers, from two hundredths of a percent down to a ten-thousandth, settle the question the name raises before a single wash. The keratin and the amino acids are the label. The silicone is the product. And once that is understood, the leave-in can be judged for what it is, which is a perfectly serviceable heat-protecting cream of the ordinary kind.

The mechanism is the one every heat protectant since the 1990s has used. Cyclopentasiloxane, second on the list, is a volatile silicone that spreads the cream thin and even through damp hair and then evaporates; dimethiconol, fifth, is the high-molecular-weight silicone it leaves behind as a film on each strand. That film slows the transfer of heat from a dryer or a flat iron into the hair's cortex, seals the cuticle so water is not flashed off in a burst of steam, and reduces friction so the brush and the iron glide instead of dragging. Cetrimonium chloride, a cationic conditioner, binds to the damaged, negatively charged patches of the cuticle to cut static and tangling, and cetearyl alcohol, glyceryl stearate and two light esters give the whole thing the body of a light cream rather than a serum. Applied to towel-dried lengths before heat, it does exactly what that chemistry predicts: hair dries faster and smoother, the iron crackles less, frizz is tamed and the ends feel soft and look shiny. None of that is unusual. All of it works.

What does not work is the story on the front. Hydrolysed keratin is a legitimate hair ingredient; in leave-in and rinse-off conditioners at working concentrations it deposits on damaged cuticle, improves tensile strength and helps hair hold moisture, and a good keratin leave-in is a real product. At 200 ppm it is not that product, and the seventeen amino acids at 1 to 24 ppm each are a roll-call rather than a treatment. The five Ayurvedic-flavoured botanicals that follow, sweet flag, water mint, holy basil, false daisy and ginger, are at the extract-level positions where such things live. Heimish deserves credit for the disclosure and a raised eyebrow for the name, and a buyer who understands the two together will not be disappointed.

The fragrance is the one thing on the list that is present at a level that matters, and it declares seven allergens: linalool, limonene, citronellol, benzyl salicylate, coumarin, geraniol and hydroxycitronellal. That is a heavy perfume load for a product that sits on the hair all day and touches the neck, the forehead and the pillow, and it is the reason the leave-in is a poor choice for anyone with fragrance allergy, a reactive scalp or the kind of forehead and hairline acne that leave-in products aggravate. Cetrimonium chloride adds a second irritant if the cream strays onto the scalp. Kept to the lengths and ends on healthy skin it is fine; it is simply not a product for the sensitive.

One omission on the tube is worth naming because the category has moved past it. Most heat protectants now state a temperature, typically 230 degrees Celsius or 450 Fahrenheit, that the film has been tested against, and the better ones quote a percentage reduction in breakage from a lab comb test. Heimish states neither. That does not mean the protection is absent, since the silicone pair is the same one those tested products use, but it means the buyer is taking the mechanism on trust rather than on data, and for a product whose name begins with RX that is a gap. A flat iron run at its lowest useful setting will do more to protect the hair than any cream, and this cream is the layer that makes the low setting glide.

In use the only skill required is restraint. A pea for fine hair, a hazelnut for thick, combed through damp lengths and ends and never the roots; more than that and fine hair lies flat by the second day as the dimethiconol builds, and a clarifying shampoo every week or two keeps the film from accumulating. On air-dried hair it works as a smoothing cream, though a silicone-free leave-in would do that with less build-up, and its whole reason to exist is the heat that follows.

At twenty-two dollars list, or under nineteen on Heimish's usual discount, for 150 millilitres, it lasts two to three months at the right dose, which is unremarkable pricing for a leave-in and a premium over the drugstore heat protectants that use the same silicone pair for half the money. The premium buys the K-beauty label, the RX branding and a fragrance many will enjoy; it does not buy any keratin that does anything.

So the recommendation is plain. Fine, normal and combination hair that heat-styles regularly and wants a light, silky, well-scented cream that genuinely reduces heat damage and frizz will get that from this tube, used sparingly. Silicone-free routines, fragrance-allergic users and anyone with a reactive scalp or hairline acne should look elsewhere. And anyone buying it for the amino keratin should read the parts-per-million and buy it, if at all, for the silicone.