Basic Colour Matching – The Colour Wheel

Printers often wonder why a colour matcher will select certain pigments or colour toners to formulate their colour.

There are many reasons to use a particular pigment, including weather or chemical resistance, fade resistance, or even price. All of these constrain the ink technician, but, once the colour pallet has been set by the end-use requirements, the matcher will use the principle of the Colour Wheel to match the colour.

The Colour Wheel is a tool used to show how different pigment combinations will be cleaner or dirtier. It must NOT be confused with CIELab colour space, which is related to spectrophotometry.

Different pigments are spread around the outside of the circle, with black in the centre. To decide which colour combination to use, the matcher could draw a line between the two pigments which would give the desired colour, or, if three pigments are used, between the two which are farthest apart. The closer the line comes to crossing the centre of the circle (black), the dirtier the colour.

For example, one might use the combination of blue and yellow to match a green because this is generally the most economical combination, but might switch to green plus either a touch of blue or yellow, if a very clean colour is required.

Notice that if a line is drawn between opposite sides of the wheel, green and orange, for example, it passes through black. In actual fact, in the world of additive colour we would get a brown, which is why the colour matcher has black pigment in the pallet.

While less used in the world of spectrophotometry, the Colour Wheel still represents a basic principle of colour matching and serves as a rule of thumb for ink technicians today.