red
Let an agent specify red precisely and handle its strong conventional meanings, especially in safety signalling.
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 red precisely and handle its strong conventional meanings, especially in safety signalling.
The colour at the long-wavelength end of the visible spectrum, roughly 620-750 nm, perceived as the hue of blood or ripe tomatoes, with many shades from carmine to bordeaux.
What it is for: Signalling danger, stop and prohibition, and expressing meanings from love to warning in design and culture.
It can be specify it, in a colour space or system; use it, in signals and design, under safety conventions; produce it, with pigments or light; check contrast, for people with colour vision deficiency.
Distinguishing features
A hue, not a pigment
The safety colour for prohibition, stop and fire equipment
Hard to distinguish from green for people with red-green colour vision deficiency
Meanings differ across cultures
What it looks like
The hue of blood, fire engines and stop signs; shades range from orange-red to purple-red.
Physical character
dominant wavelength: 620-750 nm
How it is recognised
Hue angle around 0-20 degrees in HSL, or dominant wavelength 620-750 nm
Named shades: scarlet, crimson, carmine, bordeaux, Tyrian purple at the edge
Codes such as sRGB #FF0000 or Pantone 179 C
Related models
is a kind of - a hue
is used in - prohibition and fire
is produced by - red pigments and dyes
is confused with - boundary hues
In practice
Families and kinds
shades: scarlet, crimson, carmine, vermilion, bordeaux, reddish-brown
pigments: cadmium red, iron oxide, carmine, sinopia
safety red in ISO 3864 and RAL 3000 range
Identifiers
hex code #FF0000 for pure sRGB red web
RAL code 3000 series industrial reds
Standards and regulation
ISO 3864 safety colours
CIE traffic signal colour specifications
WCAG guidance against colour-only information
Failure modes and hazards
Red-green confusion for colour-blind users
Overuse diluting warning meaning
Toxic historical red pigments such as lead and mercury compounds
Also called
+88
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.red
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 red.
Red covers many shades; a value is needed.
Value
Colour space values.
Colour value
The exact value.
- Which exact red is meant, in which colour space? measurement
- Which named shade is closest? definition
Tolerance
Acceptable variation.
Tolerance
The tolerance for matching.
- How much variation is acceptable? measurement
- Does a standard fix the value, such as for safety red? provenance
Signalling Red as a signal.
Red is the main warning colour.
Safety meaning
Stop and prohibition.
Safety use
The standard meaning.
- What does red mean in this safety context? definition
- Is it backed up by shape or text? boundary
Traffic signals
Stop lights.
Signal spec
Signal colour specifications.
- Does the signal red meet the specification? measurement
- Is it distinguishable for colour-blind drivers? boundary
Accessibility Seeing red.
Many people cannot tell red from green.
Colour vision deficiency
Protan and deutan.
Colour-blind check
How it appears to colour-blind viewers.
- How does this red appear to people with red-green deficiency? measurement
- What redundant cue is provided? action
Contrast
Text and background.
Contrast ratio
The contrast ratio.
- What is the contrast ratio with its background? measurement
- Does it meet WCAG? boundary
Materials and culture Making red and what it means.
Red pigments have a long history and some are toxic; meanings vary.
Pigments
Sources of red.
Pigment
The pigment used.
- Which pigment or dye makes this red? definition
- Is it lightfast and safe? boundary
Cultural meaning
Meanings across cultures.
Meaning
Meanings in the target culture.
- What does red signify in the target culture? definition
- Could it send an unintended message? boundary
What the second pass must settle
- Which reference red should the registry use?
- How should cultural meanings be recorded without stereotyping?
- Should red pigments be separate entries?