Seven Treatments.One Distinction That Decides Everything.

Safety is not a property of the brand name; it is a property of the class, the formulation, the condition of your hair and the person applying it. As a general shape: the conditioning and coating classes act on the surface and do not permanently change the fibre, so a poor result usually fades. The bond-altering classes change the hair structurally, so a poor result has to grow out. That is the honest ranking — not a promise that any of them is risk-free for you specifically.

Nobody can tell you from the word alone, which is the whole problem with it. Smoothening is a commercial category, not a chemistry. In Indian salons it most often means a gentler thioglycolate service, but the same word is used for coating treatments sealed with heat and for milder amino-acid systems. Ask which of the four classes the service belongs to, and what the active ingredient is. If the salon cannot answer that, you have learned something useful.

They belong to the same chemical class — bonds are opened, the hair is reshaped under tension, and a neutraliser refixes them. What differs is the technique standard. Japanese straightening, or thermal reconditioning, works in finer sections with tighter process control and takes considerably longer in the chair. Better technique reduces avoidable damage. It does not turn an intensive chemical service into a gentle one.

No. Nanoplastia is a trade name with no legal or technical definition. In practice it describes an acid-based smoothing service, most commonly built around glyoxylic acid. The name is marketing; the chemistry is what matters, and the chemistry is on the ingredient list.

No, and nothing is injected. The name is an analogy for a filling and plumping effect. Products sold under it are intensive conditioning treatments — typically hydrolysed proteins, amino acids, humectants, lipids and film formers. Because there is no standard formulation, results vary substantially between products and salons.

That is the coating and conditioning end of the spectrum rather than the reducing end. Read the hair botox page if you want condition and gloss with no structural change at all, and the Brazilian and nanoplastia pages if you want a sealed, humidity-resistant surface that softens waves without permanently resetting your curl pattern.

They are the strong sulphur-to-sulphur links inside the hair fibre that hold your curl pattern in place. Whether a treatment breaks them is the single fact that determines whether the result washes out or grows out, whether you get a line at the root, and whether the change can be undone. Every other difference between these seven services is downstream of that one.

No. Water is a chemical, and so is every conditioning agent, acid, reducing agent and neutraliser used in this category. “Chemical-free” on a smoothing brochure is a marketing phrase with no meaning, and its presence is a reasonable signal to ask harder questions about what else on the page is imprecise.

An acid system works largely at and near the surface, cross-linking and sealing the fibre so it lies smooth — the underlying curl structure survives. A reducing agent opens the disulphide bonds themselves so the fibre can be reshaped. The first fades; the second, at full strength, does not.

Not necessarily. A formula can be free of formaldehyde as an added ingredient and still contain a formaldehyde-releasing agent, or contain glyoxylic acid, which behaves differently again. The regulatory record on this is covered in detail on the Brazilian and nanoplastia pages. Ask for the full ingredient list, in writing, before the appointment.

No. All seven act on the hair fibre after it has already emerged from the scalp. None of them reaches or alters the follicle, which is precisely why new hair grows in with your natural texture regardless of what was done to the lengths.

Not until that has been examined and settled. No smoothing or straightening service should go onto an inflamed or broken scalp, whatever the chemistry, and an active scalp condition needs a diagnosis rather than a styling decision. See a dermatologist first.

Investigate it. Increased shedding or visible thinning is a medical question with a cause, and a chemical process on already-fragile hair can produce breakage that looks like further loss and obscures what is really happening. Get the shedding assessed before you decide anything about a treatment.

That is a conversation for your own doctor, who knows your history, rather than for a web page or a salon. Formulations vary widely and several release volatile ingredients into what is often a poorly ventilated room. We do not give a blanket yes or no here because a blanket answer would be wrong for someone.

Heavily bleached or chemically damaged hair has less of the internal structure that every one of these processes acts on, and the bond-altering classes in particular carry a real risk of breakage. A strand test and an honest condition assessment come before any decision. A salon that skips both is not managing that risk.

A previous reaction is the strongest single reason to stop and be assessed rather than to swap brands. Take the ingredient list of the product that caused the reaction to a dermatologist, so the specific trigger can be identified rather than guessed at.

Overlap. When new product is applied over hair that has already been chemically treated, that section is processed twice, and the fibre does not get a second chance. Managing the regrowth boundary is the skill that separates a good operator from a dangerous one, and it is worth asking about explicitly.

It depends on the class and on the specific product used, and the salon that performed the service is the right source for that instruction — they know which formula was on your head. What is consistent across the category is that the aftercare window matters more for the sealing and reducing classes than for a pure conditioning treatment.

For the coating and sealing classes, a gentler cleansing routine does meaningfully extend how long the result lasts, because harsh detergents strip the sealed surface faster. For the bond-altering classes, the structural change is not washed away by shampoo — but the hair has been through an intensive process, so gentler handling is still sensible.

Both are chemical processes on the same fibre, and stacking them changes the risk profile. The order, the interval and whether it is advisable at all depend on which class you are in and on the condition of your hair. Discuss it as one combined plan with someone who can see your hair, not as two separate decisions.

This is the highest-risk question in the category, and the honest answer is that it depends on what was done, when, and to which sections. Tell any salon exactly which service you have had and how recently — before they choose a formula, not after.

Because a single number would be misleading. Cost varies with hair length and density, the salon tier, the condition of your hair and the product used, and a headline figure quoted out of that context becomes bait pricing. Each treatment page carries an indicative range with the variables that move it, which is more useful than a number here.

Not reliably. Price tracks the salon tier, the brand and the time in the chair more closely than it tracks formulation safety. What correlates better with a good outcome is a salon that will tell you the ingredient list, discuss your hair history, perform a strand test and explain how it will handle the regrowth boundary.

Stop comparing the name and start comparing the specification. Ask each one which class the service belongs to, what the active ingredient is, how long it takes, what the aftercare requires and what they will do about previously treated hair. Two quotes under the same word are frequently two different services.