Describing Colour and Influencing Factors

Colour attributes and description

1.3.1 Primary colour attributes

To describe and assess colours systematically, we use various attributes or dimensions. The three primary colour attributes used in virtually all colour systems are (see figure 5): ^{[^15]}

Hue

Hue is what we usually mean when we speak of 'colour' – red, green, blue, yellow, etc. It refers to the dominant wavelength of light and is often represented as a position on the colour circle. Hue is the most intuitive colour attribute, but at the same time the most difficult to quantify precisely.

Different sectors approach hue in different ways:

• In textiles, colour sample cards and fan decks are often used
• In coatings, precision systems such as RAL, NCS or Pantone are used
• In food, hues are often described in relation to the product (e.g. 'tomato red')

Saturation/Chroma

Saturation describes the strength or vividness of a colour – how far the colour is removed from a neutral grey of the same lightness. Other terms used for this are chroma, intensity or colour strength. A highly saturated colour is often described as 'vivid' or 'intense', while a less saturated colour is regarded as 'muted' or 'broken'

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In industrial contexts, saturation is important because:

• It is strongly influenced by pigment concentration and purity
• It is sensitive to changes in surface texture and gloss
• It plays an important role in colour harmony and combinations

Lightness/Value

Lightness refers to how light or dark a colour is, independent of its hue. It is determined by the total amount of light reflected or transmitted by a surface. Other terms for this are value or brightness (in lighting applications).

In practice, lightness is:

• Often the first attribute to change with ageing or weathering
• Strongly influenced by ambient light and viewing conditions
• Important for contrast and legibility in graphic and architectural applications

1.3.2 Secondary colour attributes

In addition to the primary attributes, there are secondary attributes that are important in specific contexts: ^{[^16]}

Gloss

Gloss is not strictly a colour attribute, but it strongly influences how we perceive colour. It refers to the ability of a surface to reflect light in a specific direction. Gloss ranges from high gloss (mirror-like) to matte (fully diffuse).

In the coatings industry, various gloss levels are defined, such as high gloss, silk gloss, satin, matte and deep matte, each with specified measurement values according to standards such as ISO 2813 or ASTM D523.

Transparency/Translucency

These attributes describe the degree to which light can pass through a material. They are particularly important in the assessment of liquids, films, coatings on transparent substrates and certain plastic products.