RAL Design System plus — hue 210
This hue is bounded at both ends. The series begins at L\* 30 and stops at L\* 90, where 160 to 200 run from L\* 20 to 93. The darkest shade is 210 30 30 Kali blue with an LRV of 9.3, the lightest 210 90 05 Tulle soft blue with 77.5. That is the window: 43 shades within a narrower margin than the neighbours offer.
So something is missing at both ends. There is no very dark blue in this hue — for the area of RAL 5011 steel blue or RAL 5004 black blue you have to go further round the circle. And there is no near-white: the highest you reach is a light blue that still reads clearly as a colour, not a tinted white. For a colour scheme in which a ceiling or a large group of light surfaces has to stay within the same hue, that is a real limitation.
Of the three colour attributes, hue is the strongest predictor of whether people appreciate a colour, and in that research blue consistently scores highest of all hues. This hue sits just short of that: with an average hue angle of 212 degrees, 210 approaches the coldest and most appreciated part of the circle, which lies at around 230 degrees.
All 43 colours in this group
More about hue 210
That is one of the few places in the system where the risk of taste is low. A shade from 210 is rarely rejected because the colour itself does not please; if it is rejected, it is over the lightness or the saturation. So when presenting to a client, in this hue you do better to move within the series than to move to another hue.
The trace of green that separates 210 from 220 is more than a fine distinction in use. Blue without green swings quickly towards grey-violet in rooms with little daylight; with a green ground the colour holds up better. 210 70 25 Maritime soft blue at an LRV of 43.1 and 210 80 25 Vibrant soft blue at 59.2 keep their direction under artificial light where a pure blue of the same intensity flattens out.
The same applies outdoors. Blue is the colour family most underestimated on the façade: under the predominantly cloudy Dutch sky a blue surface reads cooler and darker than it does on a sample, because the diffuse light is itself blue. The greener shades from this hue are less sensitive to that than the pure blues further round the circle.
On the weight scale this area is the lightest of the circle: at equal lightness, blue-violet feels less heavy than yellow-green. In practice that means a dark shade from 210 presses down less than an equally dark green or brown — 210 50 40 Atlantic blue with LRV 21.1 is dark without burdening the space. That explains its use in transport, marine applications, uniforms and corporate colours, which is how 210 50 10 Uniform green grey came by its name.
In public spaces, watch the learned meaning. Saturated blue is the colour of the mandatory instruction in safety signage. A saturated surface from this hue next to signage can be read as a sign, even when it is meant decoratively; the muted shades do not have that problem.
Blue, together with turquoise, is the area where screen and reality diverge most, and where the saturation is always shown too high on screen. Choose from the fan deck or the colour book, assess at size under the light of the final situation, and fix the colour on the A4 colour samples as the colour standard.
Technical data
Hue: 210 · Shades: 43 · Lightness: L\* 30–90 · Saturation: C\* 05–45 · Lab values: per shade on the colour page · LRV: 9.3 to 77.5 · Included in: RAL D4 A4 colour samples (colour standard), RAL D2 fan deck, RAL D3 colour book, RAL D4 atlas, RAL D6 and D8 boxes
Neighbouring hues
RAL Design 200, RAL Design 220
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