Unit 7 · Designer's vocabulary

Powder blue

HEX: #B0E0E6
RGB: 176 224 230
HSL: 187° 52% 80%
CMYK: 23 3 0 10

Powder blue or Sky blue?

Paler and greyer than sky blue.

History

Powder blue was a product before it was a shade. In the 1650s it meant powdered smalt, ground blue cobalt glass, sold to laundresses. A pinch in the rinse water tinted yellowed linen just enough to look whiter, a trick called bluing. Only in the 1890s did the name settle on the soft pale blue we know.

Science

Bluing works because a faint blue cancels a faint yellow, its complement, and the cloth reads as neutral white. Modern detergents do the same job with optical brighteners, which soak up invisible ultraviolet and give it back as a faint blue glow.

Kin

Cobalt: The original powder blue was ground cobalt glass
White: Laundry blue made yellowed whites look white again
Yellow: Bluing works by canceling yellow

Sources

Wikipedia, 'Powder blue' (1650s smalt; color name from 1894)
Wikipedia, 'Bluing (fabric)'; 'Optical brightener'

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