cold light

I. The bender

A neon tube begins as a straight length of glass, four feet long, and a paper pattern drawn full-size on the bench. The bender heats one section in a ribbon of flame until it goes slack, lifts it out at the moment before it slumps, and lays it against the pattern by eye, blowing gently down a hose so the softened bore does not pinch shut. There is no gauge for the moment before it slumps. It lives in the hand, and the hand is trained by ruining a great deal of glass. In the United Kingdom, by one recent count, twenty-seven people do this full-time. There are no trainees. The people who know how have often been unwilling to teach, on the grounds that a student is a competitor with a ten-year head start on the rent.

II. The name is wrong

Most of the glowing tubes over the bars and the barbershops contain no neon. Neon gives one color — a hard orange-red — and only that. Everything else is argon with a bead of mercury, which together throw off ultraviolet light the eye cannot see, and a phosphor painted inside the glass converts the invisible line into blue, green, gold, pink. A blue “neon” sign is a fluorescent tube — the same lamp as the one in the office ceiling — bent by hand into a word. Fewer than one glowing tube in ten is actually neon. The gas you are looking at is almost never the gas you were sold.

III. Light without a wire

There is a kind of tube that needs no transformer, no socket, no switch. It is a sealed vial of borosilicate glass, a phosphor coating on the inside, and a small charge of tritium — hydrogen carrying two extra neutrons it cannot keep. The tritium decays, shedding electrons one nucleus at a time. The electrons strike the phosphor and it glows. They are so slow they cannot cross the glass wall; they cannot cross the outer dead layer of human skin. The whole reaction stays inside the tube. A green one shines at about two candela per square meter — a hundred times dimmer than the screen you are reading this on, bright enough only in the dark. It is plugged into nothing. It is lit by an isotope quietly coming apart.

IV. It dies twice

The light fades two ways at once. Tritium has a half-life of a little over twelve years, so every twelve years there is half as much of it left to decay and half as many electrons thrown. That alone would be a slow, clean dimming. But the phosphor is bombarded the entire time, and phosphor wears out under bombardment; in the same twelve years it loses more than half its brightness on its own account. The fuel runs down and the thing that turns fuel into light burns out, and neither waits for the other. What began bright ends as a faint green suggestion, killed from both ends.

V. The trade

Before tritium there was promethium, and before promethium, radium. Radium was the brightest — it needed no fresh charge and glowed for a human lifetime — and it was painted onto watch dials by women who shaped the brush tips with their lips. It went on glowing in their jaws long after. Every replacement since has run the same trade the other direction: a little less light bought with a great deal less harm. Tritium won because its particles are weak, its biological half-life is twelve days, and it leaves the body with water. The dimmest of the three is the one still in use.

VI. No switch

A neon sign is attended at every point of its life. A hand bends it, a transformer feeds it, a person throws it on at dusk and off at close, and the instant the tube cracks the light stops. The tritium sign over the fire door is attended by no one. It was hung once and will not be touched again for twenty years. It cannot be switched off. It glows in the sealed box on the shelf, in the crate on the truck, and when it is finally discarded it glows in the dark of the landfill, dimming on its twelve-year schedule, marking the way out of a fire that, in all likelihood, never comes.