Ironclad Alizarin
Ironclad Alizarin (#D31B3E) is a true red with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (349°, 77%, 47%) places it in the highly saturated band at a mid lightness. Best used in small doses, like logos, CTAs, focus rings, or highlight text, where its saturation becomes a feature rather than noise. For a confident two-color system, pair it with its complementary teal. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
English compound iron + clad — referring to the 19th-century USS-Monitor and CSS-Virginia iron-armored warships. As a color modifier, ironclad implies a saturated-and-armored-and-impenetrable quality where the hue carries the visual weight of forged-iron armor-plate. Sits at the bold-and-fortified end of the grid, parallel to fortified and armored.
1,2-dihydroxyanthraquinone — the principal anthraquinone dye component of madder root (Rubia tinctorum), first isolated and synthesized in 1869 by Carl Graebe and Carl Liebermann. Alizarin color refers to a freshly alizarin-mordant-dyed wool: a saturated, slightly cool deep magenta with the matte finish of anthraquinone-dye-on-mordanted woolen fiber. The first natural pigment to be replaced by a synthetic.
Closest matches
The nearest named color in three reference sources, ranked by perceptual distance (ΔE76 in CIELAB). ΔE < 1 is imperceptible to most viewers; ΔE > 10 is clearly different. When two sources point to the same hex they’re merged into one tile; click any to open that color’s page.
Variations
Click any swatch to exploreHarmonies
Accessibility
How this color appears to viewers with the four major color-vision-deficiency types. Computed via the Machado (2009) physiologically-based model. If a tile matches the original, the color reads the same to that viewer.
The color used as foreground text against pure white and pure black, with the contrast ratio and WCAG 2.1 grade. Aim for AA (4.5:1) for body text and AA Large (3:1) for 18 pt+ headlines; AAA (7:1) is the gold standard for long-form reading surfaces.