Our topic for today is the HKS colour palette for spot colour printing. HKS® is a registered trademark owned by HKS Warenzeichenverband e.V., a consortium composed of three companies: Hostmann-Steinberg GmbH, K(ast)+E(ich) Druckfarben of the Flint Group Germany GmbH and H. Schmincke & Co. GmbH & Co. KG. At first, the HKS colours this consortium developed were only for the German market, but globalisation has led to their being used across the world.
What is a spot colour?
A spot colour is a full-tone discrete shade of colour which is not mixed from cyan, magenta, yellow, and key, but generated from one ink and printed directly as one colour. They are sometimes called additional basic colours in multiple print runs. As well as the full-tone hues, there are special effect colours such as gold and silver with glossy, shiny finishes.
Spot colours as trade marks
You should always try to use pre-defined spot colours if a certain shade is one of your trademarks and is one of the recognisable elements of your brand: a typical example would be the specific red used by a certain manufacturer of soft drinks. Spot colours can be reliably reproduced to the same shade, whereas standard CMYK colours are printed in four separate overlays, meaning that there can be differences (albeit minimal) between print runs.
Types of spot colour
All spot colours are defined using standards such as Pantone or HKS in tables or on colour charts using numbers or codes as unique identifiers.
The HKS colour charts
Due to the continuous changes in the basic colours available, you will find all sorts of information about how many are currently in use. At the time of writing, there are 120 basic full-tone colours available in a range of shades, meaning that there are over 3250 shades of spot colour for use on both coated and uncoated paper.
Colour consistency remains strong regardless of the printing paper used, and each of the scale palettes is assigned a capital letter for easy identification:
HKS K – coated paper
HKS N – uncoated paper for offset and letterpress printing
HKS Ek – continuous printing on coated paper
HKS En – continuous printing on uncoated paper
The numbers which often follow the capital letters stand for the intensity of the colour shade (e.g. 40 = 40%) and for the halftone percentage (the higher the value, the darker the colour). Following this system, the HKS 4 K – 40 – 30 alphanumeric combination stands for a brownish shade of yellow: HKS 4 K is the basic colour for coated paper at 40% intensity with a 30% halftone value
Can you do without HKS colours?
There are ways of translating HKS palettes into rough approximations in other colour spaces inasmuch as the HKS colour producers set the CMYK mixing ratios needed for each tone: e.g. HKS 47 is a cyan-type blue and is mixed as 1.000/0.185/0.000/0.173. This in turn is the rough equivalent of 0/172/211 (RGB) or #00ACD3 (hexadecimal). As you can tell from the fractions in the ratios, the colour result can never be entirely accurate, so you really have to make sure when printing using HKS spot colours that you are using the actual mix. If not, you could potentially end up with considerable discrepancies and lessen the recognition value of the printed material.