Sidebar · The machines

The machines

The chapters run along a chronological spine; the machines do not. From Nessler's first brass rods in 1906 to the last chandelier put away after the Second World War, the permanent-wave machine is a single object that reappears in every chapter of the thermal era — refined, contested, electrified, and finally retired. This sidebar steps off the spine to gather it into one place: a taxonomy of how the machines were wound, heated, protected, timed, powered, and abandoned. Read it alongside Chapter 4, The machine age, where most of these details first enter the record; the flat-winding and cold-wave chapters to come carry the story forward.

Two principles govern what follows. The machines are defined less by their heat than by their winding — a spiral rod and a croquignole rod are not the same tool, even when both hang from the same chandelier. And every thermal-era machine applies two things at once, alkali and sustained heat, to the keratin shaft; a generation of engineers gave its ingenuity to applying them more safely, evenly, and quickly, and none of it, until the very end, questioned whether the machine itself was the answer. This generation is also less well-documented than the chemists who followed it; workshop dates, model numbers, and the attribution of improvements are often irrecoverable, and the gaps are flagged below.

The spiral heater

The original machine is Nessler's, and Nessler's machine is a spiral machine. A section of hair is wound in a continuous spiral along the length of a brass rod, so that the rod runs through the curl like a core and projects outward from the head — period descriptions say "like horns." Each rod is then heated: in the earliest practice by an electrically heated tong clamped around it and held throughout, in the mature machine by an electric element in or around the rod itself. The spiral gives a tight, definite, lasting curl — the architecture that produced the first wave to survive washing.

Its limitation is structural. The spiral demands length — enough hair to wrap several times along the shaft. It served the dressed Edwardian long hair of 1906 and the bobbed short hair of 1924 not at all. Every spiral machine, however refined, remained a long-hair machine. This is the architecture traced in Chapter 3 and Chapter 4, and it is the architecture the bob would break.

The croquignole heater

The turning point is a different wind. In the croquignole — the flat winding — the rod is applied to the ends first and the section wrapped inward toward the scalp, the curl building in layers rather than running along a core. The rod lies flatter; far less length is required; short hair, for the first time, can be permanently waved. Presented by Josef Mayer in 1924, the croquignole did not improve the spiral machine so much as make it obsolete for the dominant hairstyle of the new era. (Mayer's flat-winding priority, and the patent family it produced, are the subject of the chapter to come; the Mayer-Realistic archive carries the primary documents.)

The croquignole heater — shorter, often padded at the base, in the mature form clamped rather than suspended — is the immediate ancestor of every salon perm rod in use for the next half-century. With it, the machine stopped being an instrument for the long-haired few and became one for the bobbed millions. It was not a better spiral machine. It was a different one.

Spiral — wound along the length (long hair) Croquignole — wound from ends to scalp (short hair)
Fig. 1. The two windings that define the thermal-era machine. Left: the spiral rod of the Nessler generation, hair wound along the shaft so the rod projects outward — a long-hair instrument. Right: the croquignole rod of the Mayer generation, hair wound from the ends inward toward the scalp, lying flatter — the short-hair instrument that made the perm mass-market. The chandelier, the timer, the heater element could be shared between them; the wind could not. (Author's schematic, after period apparatus in the Science Museum Group and Historic England collections.)

Pads, protectors, and the scalp

The constant hazard of the thermal machine was the scalp. Every rod carried a countercurrent of rising heat toward the skin; every alkaline paste was an irritant held against it for hours; and the earliest practice rested the bare brass directly on the head. Nessler's first attempts raised blisters on his test subject's scalp. The mature machine grew a layer of insulation between rod and skin: a felt or flannel protector, sometimes moistened, sometimes supplemented by a comb-like interposer lifting the hot metal clear of the root.

The patent record is curiously late to name them. A discrete "scalp protector" appears as such only toward the end of the 1920s; the practice is visible in the early-1920s apparatus and is already implicit in Nessler's 1914 short-hair scalp heater (GB191408117A). The honest reading: the protector was an operator's habit before it was an inventor's claim — a felt pad pulled from a drawer and laid between brass and brow, an unpatented kindness that kept the trade alive before the lawyers caught up with it.

1906 → late 1920s
London & the trade

The scalp protector evolves from operator's habit to patented component. Nessler's 1906 machine rests bare brass on the skin; the 1914 improvement implies an interposer; by the late 1920s the felt protector is a named, marketed part of the apparatus. The hazard it addressed never disappears — only the machine's retirement ends it.

Timing and control

The earliest operator judged by eye. Each rod was clamped, watched, and released when experience said the curl had taken — a skill transmitted apprentice-to-apprentice and a source of endless variation between salons. The trade press of the late 1910s begins to describe a different arrangement: mechanical timers fitted to the machine, allowing each heating to be clocked rather than guessed. The improvement is attributed, in the main, to the Icall workshop in London — Isidoro Calvete's firm, which built the Eugene-system machines — though no single "first timer" patent has been cleanly identified, and the attribution must carry that caveat.

What the timer tamed was not the heat itself but its duration. The controlled-heat problem — keeping a rod to a predictable temperature rather than letting it scorch — was approached differently. Bimetallic thermostats belong to the 1940s and 1950s, outside the thermal era. The earlier machines held temperature by the steam-and-water phase-change ceiling of their heater designs — boiling water absorbs the surplus heat — and by manual switching. Suter's 1917 differential heater (GB111372A), running two independent coaxial circuits so the coarser root hair could be heated longer than the finer tips, was the most consequential step.

The machine age never invented the thermostat. It held the heat steady the older way — by letting water boil, and by trusting the operator's hand on the switch. The timer only clocked what the eye had always guessed.

Power and heat

The thermal machine is, at bottom, an electric appliance — and its ancestry is older than the current that feeds it. The heated curling iron runs in an unbroken line from the bronze tongs of pharaonic Egypt through the spirit-lamp Victorian instruments of Chapter 1. Nessler's decisive break was not the heat but the controlled, sustained, electrical heat: a current passed through a brass element for as long as the keratin required, with no flame to tend and no iron to re-warm. Gas, coal, and spirit-lamp heaters belong to the prehistory; the permanent wave begins when the current is switched on.

What is easy to miss, looking at one machine, is the aggregate load. A mature chandelier of twenty rods, each drawing current for minutes at a time, asked a great deal of the salon's supply. The overhead suspension — counterweighted rods from a frame above the seated client — was as much a wiring architecture as a mechanical one, distributing current to many heaters from a single ceiling point. For the first decades of the century, the premises that could house a permanent-wave machine were a subset of those that could power one.

Why the machines faded

The thermal machine did not die of failure. It died of weight, time, danger, and — finally — of war. The mature chandelier was heavy: brass rods, counterweights, and live current suspended above a client who sat beneath it for hours, motionless, scalp insulated and irritated, the air close with heated keratin and alkali. The six-hour sitting of Nessler's first practice was compressed by the machine-age engineers, but never to nothing; the perm remained a morning set aside. The danger never fully retired either — however refined the protectors, the machine applied live current and hot metal to a seated head for the length of a working morning, and the risk of burn kept the thermal perm a specialist service.

Then the war came. Wartime rationing of metal and electricity — the very things the machine was made of and fed on — finished what chemistry had begun. By the early 1940s the cold wave, needing no chandelier and no live current, was overtaking the salon. The machineless turn was honest: the thermal machine had carried the lasting curl from 1906 to the threshold of the 1940s, and after that the chemistry did the work, and the brass was put away.

What remained, after the machines, was the wind they had established. The croquignole flat winding survived the cold wave, the acid perm, and every later chemistry, down to the salon rod of the present day. The machine was a means; the winding was the idea.

Sources & further reading