There are two methods we use to get an image onto the pieces of metal that we use for our printing, and in this blog entry we’re going to look at white toner transfer printing on metal. The other method is dye sublimation printing which is covered in another article.
In order to get more realistic colour matching in almost any form of printing, the ink has to be on a fundamentally white background. Without getting too technical, that’s because normally a colour printer (even a big commercial printing press) prints the four ‘process’ colours cyan, magenta, yellow and black which build up in layers to form your full colour image. This process is “subtractive” – in other words each layer of ink reduces the colour range that you see from white to a more limited gamut, until the final layer is on and you see the colour as it was intended. RGB, which is the process that cameras, scanners, TVs and monitors use, is “additive” – red, green and blue light is added to a black background to build up the colour.
So, when we print direct to metal or wood using dye sublimation, we don’t get quite such a true colour, because we’re ‘adding’ cyan, magenta, yellow and black to a background that ISN’T white – it’s whatever shade the metal or wood happens to be. It looks amazing with the right picture, but some pictures – for example, anything with blue sky, or green country scenes – simply don’t work very well. The solution? We print the white background onto the metal UNDER the image.
So, when we create a white toner transfer print, we first print the image in reverse (a mirror image) on a sheet of specially prepared paper, and the LAST layer to be printed is a layer of solid white ink on top of all the other image areas. Then we transfer this to the metal using heat and pressure – because we’re transferring it, the white top layer goes onto the metal FIRST and becomes a kind of ‘undercoat’ that the other colour layers can go on top of, to build up the colour as you would on a sheet of white paper. That way, the cyan, magenta and yellow inks (we don’t use black, because the first three added together give a perfectly good black for most images we print) can build up into an image exactly as they would in a colour laser printer.
White toner transfer printing on metal is an excellent way to print any image that has more ‘naturalistic’ colours – greens and browns, sky and light clouds, flowers, trees and people. Many of our stock images print very well as white toner transfer, and we can print your own images using either method.