blue
Let an agent specify blue precisely and handle its meanings in signalling and design, and its accessibility.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
written by Claude from model knowledge without web access - no source was read, every claim is a lead to verify
Researched by: Claude
Purpose and description
Let an agent specify blue precisely and handle its meanings in signalling and design, and its accessibility.
The colour between violet and cyan in the visible spectrum, around 450-495 nm, perceived as the colour of a clear sky, with shades from azure to petrol blue.
What it is for: Signalling information and mandatory actions, and expressing meanings in design and culture.
It can be specify it in a colour space; use it in signs and design; produce it with pigments or light; check contrast.
Distinguishing features
A hue between violet and cyan
Mandatory action colour in safety signs
Historically rare and costly pigments
Blue light has health and display considerations
What it looks like
The hue of a clear sky and deep sea; shades range from cyan-blue to navy.
Physical character
dominant wavelength: 450-495 nm
How it is recognised
Hue angle around 200-250 degrees in HSL
Named shades: azure, duck-egg blue, petrol blue
Safety blue for mandatory signs
Related models
is a kind of - hue
is used in - mandatory
is produced by - blue pigments
is confused with - boundary hues
In practice
Families and kinds
shades: azure, navy, cobalt, petrol blue
pigments: ultramarine, cobalt blue, Prussian blue, YInMn blue
safety blue (ISO 3864)
Identifiers
RAL code 5000 series industrial blues
Standards and regulation
ISO 3864 safety colours
WCAG contrast
Failure modes and hazards
Low contrast of dark blue on black
Blue-yellow deficiency (rare)
Some historical pigments are toxic
Also called
+59
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.blue-animal
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 4 bundles · 8 layers · 8 findings · 16 questions.
Specification Which blue.
Blue covers many shades.
Value
Colour values.
Value
Exact value.
- Which exact blue is meant, in which colour space? measurement
- Which named shade is closest? definition
Standard
Safety blue.
Standard
Standardised blue.
- Does a standard define this blue? provenance
- What tolerance applies? measurement
Signalling Blue as a signal.
Blue means mandatory action in safety signs.
Meaning
Mandatory signs.
Meaning
Meaning in context.
- What does blue mean in this sign system? definition
- Is a pictogram used too? boundary
Lights
Emergency lights.
Lights
Blue lights.
- Which vehicles may use blue lights here? boundary
- What must drivers do? action
Accessibility Contrast.
Contrast matters for readability.
Contrast
Ratio.
Contrast
Contrast ratio.
- What is the contrast ratio with its background? measurement
- Does it meet WCAG? boundary
Colour vision
Tritan.
Colour vision
Colour-vision check.
- How does it appear with blue-yellow deficiency? measurement
- Is a redundant cue provided? action
Materials and culture Pigments and meaning.
Blue pigments have a rich history.
Pigments
Sources.
Pigment
Pigment.
- Which pigment makes this blue? definition
- Is it lightfast and safe? boundary
Culture
Meanings.
Meaning
Cultural meaning.
- What does blue signify in the target culture? definition
- Is it tied to institutions or brands? boundary
What the second pass must settle
- Which reference blue should the registry use?
- How should cultural meanings be recorded?
- Should blue pigments be separate entries?