Matching paint to ink - ink, paint it ain't

When a piece of timber is treated with a coloured, transparent stain, the resultant effect is influenced by the colour of the timber itself and the amount of stain applied. Light travels through the stain to the timber and is then reflected from the timber surface through the stain. Light timbers (such as pine) obviously reflect more light back than dark timbers (such as kwila) and the thicker the layer of stain the more of the reflected light is absorbed. Paints work differently by absorbing and reflecting light from its own surface and, once hiding is achieved, further coats do not affect the colour. The colour of painted timber can not match the composite colour of the stained timber.

Many printing inks are transparent and achieve their final colour effect by incorporating the light reflected by the base stock and, just as the colour of the timber affects the stained colour, so does the colour of the stock affect the perceived ink colour. Reflex Blue applied over kraft paper is a vastly different colour to the same ink applied over white paper. Even with white paper, the colour achieved by the same ink over coated or uncoated stock is very, very different. Just as painted timber can not match the colour of stained timber, nor can opaque paint match the colours of surfaces coated with transparent inks.

To make things more complicated, many ink colours are not transparent but use similar pigmentation to paints. As you would have guessed, these inks can be quite accurately matched by paints.

The message? Simply that specifying paint colours from a printing ink fandeck is absolutely fraught, with the quality of the match depending entirely on the degree of transparency of the ink!