Perm vs Relaxer

One word, two directions of travel

In this salon, and across this library, a perm means adding curl, wave or volume. That is what the word means in Britain, in most of Europe, and across the Asian salon markets. In much Black-hair usage, particularly American, a perm means a relaxer: a service that permanently straightens tightly coiled hair. Both usages are correct in their own rooms. They describe opposite results.

The word itself is a nineteenth-century marketing decision that stuck. “Permanent” distinguished chemical or heavy-heat alteration from a water set, which washed out. It was never a description of direction, and so both directions took it.

The two streams grew up separately. Karl Nessler demonstrated a thermal permanent wave in London on 8 October 1906 and patented the process on 6 February 1909, working on straight European hair and adding curl. Garrett A. Morgan came upon a chemical hair straightener in the years around 1909 and commercialised it from 1913 through his own company, working on tightly coiled hair and removing curl. For most of the century those were separate trades with separate suppliers and separate training, and each simply called its own service a perm.

Ask for a perm in Mayfair and someone reaches for rods. Ask for a perm in a salon specialising in Afro-textured hair and someone reaches for a cream. Neither is wrong. Only the booking is.

The 1980s made it worse rather than better, because both services were in the same rooms at once. The Jheri curl was a two-step service — a rearranger to loosen the existing coil, then a thio curl perm to reset it into a looser pattern — and it sat on salon menus alongside hydroxide relaxers that clients also called perms. Today, with globalised menus and online booking, the confusion is no longer regional. It arrives in the notes field.

What each chemistry actually does

Both services restructure hair permanently. They do it by opposite routes, and the difference is the whole page.

A texturiser, worth naming because it is often assumed to be something milder in kind, is not. It is a hydroxide relaxer left on for a shorter time to loosen the coil rather than straighten it flat. Same chemistry, same rules, shorter clock.

Lanthionisation, and the lye that is not in most relaxers

This is the mechanism worth understanding properly, because every rule further down follows from it.

A disulphide bond is two sulphur atoms holding two protein chains together. A perm lotion splits that bond into two thiol groups — two sulphurs, both still present, both available. A neutraliser then finds them and joins them back up in whatever position the rod has arranged.

Hydroxide does not split the bond. It removes one of the two sulphur atoms and does not give it back. What is left is a lanthionine bridge, and no oxidiser on earth can rebuild a disulphide bond from a single sulphur.

That is lanthionisation, and it is why a relaxer is irreversible in a way a perm is not. A perm rearranges what is there. A relaxer permanently subtracts.

Lye, no-lye, and what is actually in the tub

The trade divides relaxers into lye and no-lye, and the division is usually explained wrongly.

Two things follow from that table. Calcium hydroxide on its own is not the relaxing agent — it is half of a two-part system, and a page or a label that names it as the active has mixed up the ingredient with the product. And “no-lye” does not mean gentle. It means kinder to the scalp and, because calcium deposits on the fibre, frequently drier on the hair. Every one of the four straightens by lanthionisation, and every one of them puts the hair permanently out of reach of a perm.

Why the two never meet, in either direction

The mechanism is the one above. Put a perm lotion on lanthionised hair and it goes looking for disulphide bonds that are no longer there to find. What it does reach is a fibre already carrying single-sulphur bridges and a much reduced protein framework, and it opens what little remains. The section softens early, will not hold the shape of the rod, and parts under a load that should not have troubled it. It fails at the line of demarcation, where treated hair meets untreated, because that line is a step change in strength.

The reverse direction fails the same way. Hydroxide on permed hair works on a fibre whose bonds have already been opened and closed once, and takes sulphur out of what is left.

Bleach lands close to the same place for a related reason, though not as an absolute. On bleached hair the answer is usually no — bleaching oxidises cystine to cysteic acid, the neutraliser needs two sulphur atoms, and there is nothing left to rebuild, so most of this hair takes a curl that drops out within weeks while the hair pays for it. Highlights and foils count, and so does grown-out bleach still sitting on the lengths. That is the default and the default is no; the exception is a judgement made on the hair in front of me rather than a rule read off a page. A relaxer over bleached hair is refused for the same absence of structure. Bleach damage sets out the chemistry in full.

Single-process permanent tint, on-tone or darker, usually survives either service, subject to elasticity and porosity testing and a strand test. That one is a judgement rather than a rule. See the diagnostic page and the porosity guide.

Two services, two completely different clocks

This is the most common piece of misinformation about perms, and it comes from applying a relaxer’s schedule to the wrong service.

So if a salon offers you an eight-week perm root retouch, it is quoting a relaxer schedule. The honest answer for permed hair between services is a cut, a set, and the right home care — and then the whole head done again when it has genuinely grown out.

Both results, incidentally, are permanent on the hair they were done to. A perm loosens over months but never reverts; a relaxer never reverts at all. In both cases the regrowth is your own texture, and the difference between the two is what the calendar is managing.

What the rest of the world calls them

English is unusual in giving both services one word. Most languages name the action instead of the permanence, which removes the ambiguity entirely.

France

Permanente curl · Défrisage straighten

Germany

Dauerwelle curl · Haarglättung straighten

Spain

Permanente curl · Alisado straighten

Italy

Permanente curl · Stiratura straighten

Japan

パーマ pāma, curl · 縮毛矢正 shukumo kyōsei, straighten

Korea

폈 peom, curl · 매집 maejik, straighten

China

烫发 tàngfà, curl · 拉直 lāzhí, straighten

Brazil

Permanente curl · Relaxamento straighten

Turkey

Perma curl · Düzleştirme straighten

Vietnam

Uốn tóc curl · Duỗi tóc straighten

Hungary

Dauer curl · Hajegyenesítés straighten

Russia

Завивка zavivka, curl · Выпрямление vypryamlenie, straighten

One small correction to a claim that circulates in the trade: perma is simply the Turkish common noun for a perm. It is not a brand, and it is not a shortening of anyone’s company name.

How to make sure you are booked for the right one

Ignore the word. Write the result.

1. Say the direction, not the noun. “I want a chemical service to add curl to straight hair” or “I want to permanently straighten my coils.” Nine words removes the entire problem, in a booking form or on the telephone.
2. Bring the history, with dates. Every chemical service, box dye, gloss, smoothing treatment and home kit for the last three to five years — and name relaxers and lighteners specifically, because both hide behind other words.
3. Expect the verbal check. A stylist who does not ask what you mean by the word, and does not look at a photograph, has skipped the only step that prevents this.
4. Expect the tests. Wet elasticity in three places, porosity by hand, and a strand test with the real product wherever there is doubt. If it softens, stays stretched or parts, the service stops there.

If a box or a stylist cannot tell you which of those two lists their product sits on, that is your answer about whether to proceed. And if you are unsure what has already been on your hair, say so plainly. It moves the appointment to a strand test, which is where an uncertain history should always go.

Questions