Colour print has been around for a long time so naturally as technology advances the machinery and printing processes change and evolve. Below is a brief introduction of the main colour print processes – they are in no particular order.
Lithographic or litho printing as it’s more commonly known is a method of printing whereby a metal plate is made with the image area and non image area both on the same plane but the image area does not hold water. Because oil (ink) does not mix with water a film of water is applied to the plate that holds in the non image area then a layer of ink is applied but only the image area picks it up because the water on the non image area is repelling and stopping the non printed parts from picking the ink up.
Letterpress printing is probably the oldest type of colour print and is based on the relief process. Invented in the mid 15th century letterpress printing has seen much advancement and some machines are still used today particularly to produce self adhesive labels. Sheetfed letterpress has largely been replaced by litho equipment but only a few decades ago newspapers and packaging was still printed letterpress.
Flexo printing is mainly used to produce self adhesive labels and packaging including carrier bags. Its ability to run at high speeds mean it’s more suited to these types of application. Traditionally a low quality process it’s now up there with litho, new types of plates and machinery mean it can hold a good range of dot sizes and produce some very nice results. Flexo like letterpress is based on the relief process.
Gravure printing is based on the intaglio process. The image area consists of small cells on the surface of the plate. These cells fill with ink and the excess gets scraped off with a blade then an impression roller presses the substrate against the plate to transfer the ink to the paper. Gravure printing is normally used to produce good quality high volume work such as stamps, cigarette packets and magazines.
Digital colour print has come a long way in the last 10 years. There are various types of digital presses which carry a huge difference in price and ultimately in quality. Many people within the printing industry believe that digital printing is the future.