Sidebar · Glossary

Glossary

The eleven chapters and their sidebars use a working vocabulary — croquignole, disulfide bond, cold wave, bond-builder — drawn from three thousand years of practice and a century of chemistry. This page gathers those terms in one definitional reference, each cross-linked to the chapter where it is treated in depth. It is a reference, not a narrative: read sideways, not along.

A note on usage. The terms below are defined as the chapters use them. Where a word has a precise chemical meaning (disulfide bond, thioglycolate), the definition is strict; where it names a trade technique (croquignole, spiral, Marcel), the definition is operational — what the operator does, and what the result is. Dates attached to specific reagents and methods carry the same caveats as in the host chapters: established as fact, approximate as history.

A permanent wave is, in the end, one chemical transaction performed by many different means. The vocabulary below is the set of names those means have acquired.

Acid perm

The gentler, low-pH permanent wave, introduced in the 1970s. Its active agent is glyceryl monothioglycolate (GMT), a milder reducing species that works nearer the hair's own acidity than the alkaline cold-wave lotion, processing more slowly and often under gentle heat. It carried the trade through the 1970s–80s boom. See Chapter 9, The acid perm and the boom; the Chemistry sidebar.

Bond-builder / bond-multiplier

A class of treatments, appearing from the early 2010s (widely associated with the Olaplex brand from around 2014), that introduce a third step into the reduce-reshape-reoxidize sequence: a molecule that seeks out broken disulfide bonds and re-links them during and after the treatment. By restoring bonds the conventional process would lose, they cut cumulative damage and underpin the modern "texture" services. See Chapter 11, The texture renaissance.

Calamistrum / kalamistro

The ancient heated curling iron. The Greeks called it the kalamistro (καλαμίστρα); the Romans, the calamistrum — both words from calamus, the reed, because the hollow iron was wound like one. Heated in a brazier or over coals, it set a curl that washed out, exactly as the Victorian tongs would three millennia later. See Chapter 1, Before the machine.

Cold wave

A permanent wave set at room temperature by chemistry alone — no electric current, no heated chandelier. It arrived in two generations: the sulfite cold wave (c.1932, slow and smelly) and the thioglycolate cold wave (c.1940–41, fast and reliable), the chemistry the modern perm descends from. Wartime rationing of metal and electricity compressed its adoption. See Chapter 7, The cold wave and the war.

Croquignole (croquignole winding)

A winding in which the hair is sectioned flat, as a band, and rolled from its free ends toward the scalp onto a rod lying parallel to the head — the opposite of the spiral wind, which coils along a rod's length. The croquignole produced a softer, broader wave, waveable to the root, and worked on the short, bobbed hair the spiral could not serve. See Chapter 5, The bob and the flat winding.

Digital (thermal) perm

A method, developed in Japan and Korea from the late 1990s and 2000s, that hybrids the chemical and thermal lineages: the hair is first reduced with a thioglycolate- or acid-lineage agent, then wound onto rods that are themselves heated, each rod's temperature regulated by a programmable (digital) controller. The result is a soft, natural, "lived-in" curl that holds through washing. See Chapter 10, Decline and reinvention.

Disulfide bond

The direct chemical cross-link (S–S) between two sulphur atoms on neighbouring keratin molecules in the hair shaft. Strong, covalent, and water-resistant, it is what holds hair's shape through a washing — and therefore the single bond every permanent wave, thermal or chemical, must break and re-form. The reduce-reshape-reoxidize mechanism is the whole of the art. See the Chemistry sidebar.

Flat winding

See croquignole. The flat winding is the croquignole wrap as embodied in Mayer's 1924 REALISTIC system — flat sectioning, a rod lying parallel to the scalp, winding from the ends toward the root. The terms are used interchangeably in the trade; "flat winding" carries the system connotation. See Chapter 5, The bob and the flat winding.

Glyceryl monothioglycolate (GMT)

The active reducing agent of the acid perm — a milder thioglycolate species that works near the hair's own acidity (a lower pH than the alkaline cold-wave lotion), processing more slowly and more gently on the cuticle. Introduced in the 1970s, GMT is the chemistry that made the repeatable, gentle 1980s perm possible. See the Chemistry sidebar; Chapter 9, The acid perm and the boom.

Marcel wave

The crisp, regular, horizontal S-curve produced by Marcel Grateau's heated waving iron, introduced to a Paris clientele in 1872. Drawn through a dampened lock in a single reversing stroke, the curved iron creased rather than curled — giving Europe its first named curling technique. It was the salon standard for thirty years, and emphatically temporary: it washed out. See Chapter 2, The Marcel wave.

Neutralizer

The oxidizing solution applied after the waving lotion, once the hair is wound and shaped. It withdraws electrons from the free thiol (S–H) ends left by the reducing step, allowing the sulphur atoms to re-link as disulfide bonds — now in the geometry the rod imposed. The re-formed bonds are identical to the originals, which is why the wave survives washing. See the Chemistry sidebar.

REALISTIC system

Josef Mayer's practical flat-winding system, presented in 1924: flat sectioning, an integrated scalp-protector clip at each strand base, controlled tension on a rod lying flat against the head, a sealed moisture-retaining sachet, and sectional sleeve heating. It compressed a full-head treatment to roughly ninety minutes and made the perm reproducible, teachable, and safe for the bob. See Chapter 5, The bob and the flat winding.

Spiral winding

The Nessler-era method: a long lock wound in a continuous coil along the length of a rod that projects from the scalp, so that the rod runs through the curl like a core. The spiral produced a tight spring-curl and demanded hair long enough to coil — which is why the post-war bob rendered it, and every machine built around it, obsolete overnight. See Chapter 3, The first permanent wave.

Thioglycolate

The reducing agent of the commercial cold wave — most commonly an alkaline solution of ammonium thioglycolate. It breaks the disulfide bonds far more efficiently than the earlier sulfite lotions, at a workable speed and a high pH (roughly 9–10). Credited to work around 1940–41, it is the chemistry the modern cold-wave perm descends from. (Re-formed by the neutralizer.) See the Chemistry sidebar; Chapter 7.

Sources & further reading

• Robbins, C. R., Chemical and Physical Behavior of Human Hair (5th ed., Springer) — the standard reference behind the chemical entries (disulfide bond, thioglycolate, GMT, neutralizer); the reduce-reshape-reoxidize mechanism stated here rests on this established cosmetology science.
• The host chapters — Ch. 1, Ch. 2, Ch. 3, Ch. 5, Ch. 7, Ch. 9, Ch. 10, Ch. 11 — each of which treats its linked term in full narrative depth, with its own dated sources and caveats.
• The cross-cutting sidebars — the Chemistry sidebar (disulfide bond, thioglycolate, GMT, neutralizer, bond-builders), the Machines sidebar (spiral and croquignole heaters), and Patents & law (the croquignole patent estate) — for the apparatus and litigation behind the trade terms.
• Wisconsin 101 / Wisconsin Historical Society, Object History: Permanent Wave Machine (object #1980.131.1) — independently corroborates the spiral-wind / croquignole distinction and the croquignole's role in making the perm practical for shorter hairstyles.

Scope. A definitional reference for the terms used across the permanent-wave history, gathered rather than threaded through the chapters. Each entry is cross-linked to the single chapter or sidebar where the term receives its fullest treatment; the chapter index places those chapters in sequence, and the timeline places them in time. For the underlying science of the chemical entries, see the Chemistry sidebar; for the apparatus behind the winding terms, the Machines sidebar.