# On a lighting rig, a colour is a number, not a name

> A gel swatch book fans eight numbered colours from a single rivet, because an electrician orders 132 rather than pale amber, and a number refers to the same recipe every time a name won't.

August 19, 2026 · https://justog.club/stories/lighting-gel-swatch-book

Eight rectangles of colour, fanned out from one rivet at the base like a hand of cards. Cream
behind them, near-black shirt around that. Every swatch carries its own number, printed small
along the bottom edge — 021, 106, 132, 174, 201, 388, 715, 796.

Nobody who orders one of these says the colour out loud.

## What is a gel swatch book actually for?

Choosing a colour to put in front of a lantern without holding up a show to argue about what to
call it.

A sheet of coloured gel goes into a frame in front of a light and changes what colour reaches the
stage, and the same number that gets picked here often ends up scrawled beside [a lantern symbol
on a plan](/stories/lighting-plan-symbols) long before the get-in. A swatch book is that
material shrunk to sample size and bound at one edge, so a designer or an electrician can hold a
whole range of colour against the same light in seconds and settle on one before the moment's
gone.

## Why does everyone use the number instead of the colour's name?

Because a name is somebody's opinion and a number is a thing you can order.

Ask five people what "pale amber" means and you'll get five different colours in their heads. Ask
for a specific number and a wholesaler somewhere pulls the same sheet every time, because the
number refers to one exact dye recipe rather than a description of how it looked to whoever named
it, under whatever light they were standing in that day. The number is the part of the system
that doesn't drift.

## Why does the book fan from a single rivet?

Because it has to be usable in one hand.

An electrician up a ladder, or crouched by a lantern with a spanner in the other hand, needs to
flick through a whole range of colour without setting anything down. A single rivet at one corner
lets the whole book open like a hand fan and close again the same way, which a book bound the
ordinary way, along one full edge, wouldn't do nearly as fast. Once a number's chosen it tends to
stay chosen — the same figure often gets loaded straight into [a preset panel set once and reused
for a year](/stories/house-light-preset).

## Does a gel maker own their own numbers?

The numbering system does, and that's an entirely ordinary thing to license.

A specific manufacturer's catalogue — the exact number attached to the exact recipe they sell —
belongs to the company that built the range, the same way a paint maker owns its own colour names.
The numbers on this design are invented rather than lifted from a real range, which avoids that
question rather than needing to answer it. Nobody, meanwhile, owns the idea of a swatch book, or
the fan-from-one-rivet format itself.

## Does this only mean something to a lighting electrician?

No — anyone who's had to standardise a choice that used to be a matter of opinion recognises it.

A print shop's colour-matching book runs on exactly the same logic: a name invites an argument, a
number ends one. The gel book earns its place on a shirt for the same reason a matching chip does
on somebody who's spent a career pinning down colour for a living — it's a badge for the
unglamorous work of turning "roughly that colour" into something you can actually specify.

## Isn't picking eight colours out of hundreds a strange thing to reduce to a shirt?

Not if the eight are the ones somebody actually reaches for.

A working electrician's own kit is never the full range a manufacturer sells — it's the handful of
numbers that come up again and again on the shows they've actually rigged, memorised the way
anyone memorises a tool used daily. Eight fanned swatches read as exactly that kind of personal
shortlist, not as an attempt at the whole catalogue.

## Does it print well?

Yes, and the number is the part that has to survive.

Flat, saturated colour blocks print cleanly with hard edges between them, which a fanned swatch
shape gives you for free. The number stamped along each swatch needs to stay legible at a size
larger than a real gel book uses — shrink it to match the genuine article and it disappears into
the weave, and the whole point of the design is that the number can be read.

## How do I get one made?

Describe your own range at [JustOG](/) — how many swatches, which colours, and how they should
fan. Pick a direction, drag the crop frame, see it composited on the real garment, and it's made
to order and shipped.

Designs other people have published are in the [shop](/shop).

Eight numbers, no names, and every one of them orderable at four in the afternoon.