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Colour Coding in Wayfinding Signage: Rules That Hold Up

Colour coding is the most copied idea in wayfinding and the most often botched. Done well, a visitor can follow the blue corridor to the blue wing without reading a word. Done badly, the building has six colours, two of them look the same under the lights, and staff have stopped mentioning the scheme because it confuses people.

What colour coding is for

Colour does one job that text cannot: it works at a glance, from a distance, across languages, and for people who are anxious or in a hurry. A patient told to follow the green line does not need to read anything else until they arrive.

That is also its limit. Colour can tell someone which zone they are in or which route they are on. It cannot tell them which room, and it cannot carry more than a handful of categories before the categories stop being distinguishable. Everything that follows comes from taking that limit seriously.

How many colours

Four is comfortable. Five is the practical maximum. Beyond that, people cannot hold the mapping in their head, and the colours start to collide.

A useful test: could a first-time visitor say out loud which colour they are following, and would two visitors agree on its name? If a zone is teal and another is turquoise, the answer is no, and the scheme has already failed for anyone who was told the colour rather than shown it.

Choose colours that are distinct in hue, not just in shade. Red, blue, green and yellow are the classic set for a reason. Add purple or orange if you must; avoid adding a second blue.

Colour-blind visitors, which is one man in twelve

Around eight percent of men and half a percent of women have some form of colour vision deficiency, most commonly a weakness distinguishing red from green. A scheme that relies on red versus green alone will fail a measurable share of every crowd.

The fix is not to abandon colour, it is to never let colour be the only carrier. Pair each colour with a name (Blue Wing, not just blue), a letter or number, and where you can, a shape or icon. When a sign says Blue Wing on a blue panel, everyone gets it, including the person who sees the panel as grey.

This is also why the colour must be repeated as text on directories and in any confirmation letter or email. A patient who reads follow the blue line in their appointment letter has a plan before they arrive.

Contrast, materials and lighting

Colours that look distinct on a designer's screen can merge on a wall. Three things cause it.

Lighting changes hue. Warm artificial light pushes everything toward yellow, so a lime green and a yellow that were fine on paper can read as the same colour in a corridor. Test swatches in the actual building, in the actual light, at the actual mounting height.

Text still needs contrast against the panel. A white label on yellow fails the 4.5 to 1 ratio that accessibility standards expect, and so does dark grey on navy. Check every text and background pair you plan to use, not just the panel against the wall.

Materials fade unevenly. Reds go pink in sunlight faster than blues go pale. If a scheme runs outdoors and indoors, specify the outdoor material to a higher fade rating or the two will drift apart within a couple of years.

Where the colour goes, and where it should not

The colour belongs on the elements a visitor uses to navigate: zone identification signs, directional arrows for that zone, floor lines or wall bands if you use them, and the directory. It does not belong on everything in the zone. Painting every door, bin and notice board blue does not strengthen the code; it buries it.

Decide at the outset whether colour marks a zone (the blue wing) or a route (the blue line to radiology). Mixing the two is the commonest structural mistake. If the blue line runs through the green wing, visitors following either one lose confidence at the crossing.

Regulatory signage keeps its own colours by law. Fire exits are green, prohibitions are red, warnings are yellow. A wayfinding scheme that uses green for the paediatrics wing will have visitors following exit signs into stairwells. Check the safety colour set before choosing yours.

Keeping the scheme alive

A colour scheme dies by accretion. Someone orders a replacement sign and the printer matches the colour by eye. A department moves and its signs move with it, into a zone of a different colour. Five years on there are two blues and nobody remembers which was right.

Write the scheme down as a one-page standard with exact colour references, the zone each colour means, and the rule for what happens when a department relocates. Give it to whoever orders signs. That page is the difference between a scheme and a collection of coloured signs.

For the detail behind the colour, meaning which departments are in the blue wing this year, a scannable map beside the directory is easier to keep current than a printed list. QRCodeMaps is built for that layer, from $99 a month with a free trial.