Sublimation or heat transfer printing is the application of sublimation inks onto a surface using a heat press to provide the required combination of heat, time and pressure. This combination causes the inks to be converted from a solid to a gaseous state enabling them to penetrate the sublimatable surface so that a permanent, full colour image is formed. The colour penetrates the surface of the item so that the result is colourful, long lasting and resistant to scratching unlike some other printing methods that merely print onto the surface of the item.
What is Sublimation printing?
Dye sublimation printing is always done on a polyester, polymer, or polymer coated item. At high temperatures, the solid dye converts into a gas without ever becoming a liquid.
The same high temperature opens the pores of the polymer and allows the gas to enter. When the temperature drops, the pores close and the gas reverts to a solid state. It has now become a part of the polymer. For this reason true dye sublimation cannot be done on natural materials such as 100% cotton. Natural fibres and non-coated materials have no "pores" to open.
An image is transferred to the printed surface by ink, which is pressed through a stenciled screen and treated with a light-sensitive emulsion. Film positives are put in contact with the screens and exposed to light, hardening the emulsion not covered by film and leaving a soft area on the screen for the squeegee to press ink through. Also, you must create a different screen for every colour you are going to print, and then screen each colour separately allowing drying time in-between.
4-color Process
A system where a colour image is separated into 4 different colour values by the use of filters and screens (usually done digitally). The result is a colour separation of 4 images, that when transferred to printing plates and printed on a printing press with the coloured inks cyan (blue), magenta (red), yellow and black, reproduces the original colour image. These four colours can be combined to create thousands of colours just as your computer printer does.