On a lithographic press, an aluminium printing plate is first coated with water which is repelled by the image, followed by a coating of printing ink which is repelled by the water thus “inking up” the required image. This image is then transferred to the paper via a system of transfer rollers.
This method is fast and extremely accurate. Ink dots can be incredibly small in litho printing ensuring extremely fine detail can be reproduced. Our Heidelberg presses have fantastically accurate registration which means every one of these tiny dots lands in exactly the correct place on each passing sheet of paper – even if the sheets are whizzing through at a rate of 15,000 per hour.
Conversely, a digital printing press uses toner, transferring the image to the paper using positive and negative electrical charges. Digital presses are constantly improving but cannot get close to lithographic presses for print run speed. The process uses a different dot structure and is not quite as accurate as litho in registration but is accurate enough and processes quality colour images. Digital printing is limited to four colour process (CMYK) What is CMYK whereas a lithographic press can be loaded with any one of thousands of coloured inks (see SPOT COLOUR PRINTING)
Why not use lithographic printing all the time?
Simple answer: because digital printing is extremely cheap to set up in comparison. For each colour used in lithographic printing, a separate plate and inking unit is required. The production of a plate and the skill required to set up the inking units does, unavoidably, have a higher basic set up cost.
As a result, digital will always work out much cheaper on shorter runs and litho much cheaper for higher runs. Therefore the two process complement each other ensuring that whether you want 50 invitations or 10,000 brochures – we have the means to produce them by the most efficient method.
Spot colour litho printing
Our lithographic printing service has another major advantage over digital printing – we can match any one of thousands of Pantone® colour inks. Fewer and fewer printers offer this service these days as it is a specialist skill. Spot colour printing is alive and well here at Gowise – read more on our dedicated page Spot Colour Litho Printing