Brown is still brown, forty years on

Eight lengths of wire, each a different colour, cut and set in a vertical key. Brown is PERMANENT LIVE. Blue is HEADLAMP. Red is SIDELIGHT. Purple is PERMANENT ACCESSORY. Green is IGNITION-FED. Light green is INSTRUMENT. Black is EARTH. White is IGNITION.

At every cut end, the copper shows. Nothing here is printed. The information is the wire.

What is this, exactly?

A colour code for a wiring loom — the convention that tells an electrician what a wire does by looking at its insulation, not by tracing it back to a label.

Eight functions, eight colours, and no words anywhere on the actual loom itself. The lettering beside each length in this design exists for the reader; on the real wire, there's nothing but the colour.

Why does colour work as documentation at all?

Because it can't fall off, fade past reading, or get filed in the wrong folder.

A paper diagram tears. A printed label peels, much the way a windscreen sticker starts lifting at the corner. A manual goes in a skip when somebody clears out a garage. The insulation on a wire is the wire — there's no separate object to lose, which makes it about the most durable documentation format built into any machine.

A fuse box a few inches away still needs its own printed chart for the opposite reason — a fuse carries an amp rating, not a colour convention, so somebody has to write down what it does rather than let the part say it.

What makes a colour code good rather than just consistent?

Consistency across the whole loom, first — every ignition-fed wire in green, everywhere, or the code is worthless. Beyond that, contrast: a green next to a light green only works if somebody can actually tell them apart in poor light, which is why a second wire in that family usually carries a trace of another colour rather than a third shade nobody can distinguish from the first two.

Can a real manufacturer's actual colour code go on it?

The convention itself — colour standing for function — is a method, and belongs to nobody, the same way a torque sequence is a fact rather than a brand.

A specific manufacturer's exact published code, tied to their part numbers and their diagrams, is a different thing, and licensable the usual way if a real one is the point of the shirt. Eight generic colours against eight generic functions carry the same idea without needing anybody's permission.

What happens when two electricians don't share a code?

They read the loom differently, which is the one real weakness of a system with no words in it.

There's no single code every era and every maker has used — green has meant different things in different systems. That's less a flaw than a reason the colour key gets kept, printed or stitched, next to the loom it describes, so the convention travels with the wire even where the convention itself isn't universal.

Does it work as a gift, or only as a trade shirt?

Both. For an electrician, it's their actual working vocabulary printed flat. For anyone who's restored a car with somebody else — a parent, a friend who owns the workshop — it's a fair description of the hours actually spent: mostly bent over a loom, working out which cut end is which by colour, one wire at a time.

Does it print well?

About as well as any print can — this is a chart made entirely of flat colour with hard edges, which is exactly the kind of artwork fabric printing rewards. No gradients, no fine detail below the weave's floor beyond the lettering, which wants setting a size larger than the real key would carry it.

Black as a ground lets all eight wire colours read true rather than shifting against a competing background. This is one of the few designs here where the ink count is the whole point — eight colours, used as data rather than decoration.

How do I get one made?

Describe the loom at JustOG — which functions to include and how many wires to key. 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.

Copper at both ends, and the colour in between says all of it.