Color theory and color placement: the NCS system and color choice in the painting craft.

Much of the building painter's expertise is about colour — not just being able to paint evenly, but understanding how colours behave, how they work together, and how to hit the exact shade a customer or architect has asked for. Colour theory is therefore a fixed part of the training, and it is built in Denmark and the rest of the Nordic region largely on the NCS system.

NCS (Natural Colour System) was developed by the Swedish Skandinaviska Färginstitutet and has roots back to research from the 1930s. The system describes colours based on how humans actually perceive them rather than which pigments or mixtures lie behind them. This makes NCS suitable for colour specification because two colours with the same NCS value are perceived the same regardless of which product or producer they come from.

Color correction and color grading are often used interchangeably, but they solve two different tasks. Color correction is about fixing errors: wrong white balance, different exposure between clips from the same scene, or cameras that don't match in color. Color grading comes after and is about giving the material a deliberate, artistic expression — cold and pale, warm and saturated, or what the story calls for.

• 01Coloured, saturated colours draw attention and can seem dominant in large areas
• 02Light, muted shades give rooms a calm feel and appear larger
• 03Contrasts between walls, ceilings and trim can emphasize architecture or hide unevenness
• 04The same colour can look different depending on light and time of day

Where NCS is built on human colour perception and has a very large number of nuances, RAL is a German industrial standard with a fixed set of 216 colours identified with four-digit numbers. RAL is used especially in industry and painting, while NCS dominates in Scandinavia for buildings, interiors and architecture. As a painter you encounter both systems, and it is important to be able to translate between them when a customer comes with a code from one system but the product must be mixed according to the other.

Today most paints are mixed by machine. A colour formula is saved in the system and the machine doses pigment paste according to the formula so the same shade can be matched again and again — even years after the original task. This makes it possible to repaint a single corner without visible colour difference and is a great improvement compared to earlier when the colour had to be mixed by hand each time.

Part of the more advanced part of the trade is colour matching and colour analysis — for example when you need to recreate a specific, often old, shade on a facade or in a heritage building without a formula. Here you work backwards: you analyse the existing colour, assess its hue, darkness and saturation and work your way to a mix that matches. It requires a trained eye and understanding of how light and age affect colour over time.

“Color coding keeps areas separate (e.g. toilet and tables) so you don't cross-contaminate and move bacteria between areas.”