Conventional Printing –
There are FOUR main printing methods
Where the print and non-print areas are on the same plane surface, with the difference between these areas being maintained by physical or chemical properties, the examples of these are OFFSET LITHOGRAPHY, COLLOTYPE and SCREENLESS PRINTING
There are a wide variety of printing techniques, some traditional and still viable, some ultra-modern digital systems and with a huge advancement in media, inks and requirements it is a minefield to determine which is the best choice for the humble printer to select. So here are the main choices today
Lithographic, Offset Lithography, Litho, Offset or Plate Printing
This is where the image or the content that one wants to produce is placed on a plate which is usually manufactured from aluminium,this is then inked when only the image part will hold the ink which is transferred onto a rubber blanket and then rolling that image onto a sheet of paper, it is called “Offset” because the ink is not transferred directly onto the paper, plastic, card, or other materials that must have a smooth, flat surface.A FOUR COLOUR sheet-fed printing press will typically have four towers, usually the first will deliver the Black ink, then the Cyan followed by the Magenta and finally the Yellow ink, for higher volume work a much larger Web press machine will be employed, these are usually roll-fed rather than sheet-fed, these larger web press machines operate at such a speed that they require forced drying, so a drying oven is usually attached to the end of the print line. Nowadays Litho is the most widely used printing method for Newspapers, books, stationery, corrugated board, posters, etc. The benefits of using Litho printing as opposed to Digital Printing will be covered in a subsequent paragraph.
Flexography or FLEXO
This is the method that will be employed when the image or content that needs to be printed is on a relief of a printing plate, this is manufactured from rubber, the plate is inked and subsequently transferred to the printing surface.This process can be used to print onto plastics, paper, metal cellophane, making it ideal for label and packaging printing., much of this Flexo work is now being produced on digital printing equipment.
Gravure or Rotogravure
This is the technique where the image to be produced is engraved into a printing cylinder, the cylinder is inked and the ink is then transferred to the paper, Gravure is used for very high volume work such as newspapers packaging, labelling and magazines.
Screen Printing or Silk Screen Printing
This method relies on a screen made from woven fabric, these used to be manufactured from silk, certain areas of this screen or mesh are coated with a non- permeable material, in the remaining spaces ink can be pushed through the screen onto the chosen substrate, the major advantage of screen printing is that the surface does not have to be flat and smooth so the ink can adhere to textiles, ceramics, metal, wood, glass and T-shirts.
Digital Printing – Xerography and Inkjet
Xerography such as laser printers, the image or content that needs to be printed is created by applying a charge to a metal drum, this electrical charge attracts toner particles, these particles are then transferred to the chosen media, to ensure that the toner is fixed properly the substrate is passed through a “Fuser” that melts the toner into the medium. Laser printers are mainly used in offices, transactional printing, banking, direct mail and small run books and brochures.
INKJET- Aqueous, Solvent, UV Curable
Large Format Aqueous inkjet printers are the most common printers available on the market today, using water as the carrier component for pigment or dye-based inks, these printers have high output, high-resolution graphics for internal or external (once laminated) usage, this printing method dominates the photographic, fine arts, retail display and trade show printing.However, it should be noted that whilst the machinery is inexpensive the aqueous inks and media really are restricted and costly compared to Solvent Media.
Solvent Digital Printing
This area of printing technology has probably seen the fastest growth, other than the fumes that are produced when printing with solvent inks( largely tackled with Eco-Solvent) the benefits and advantages massively outweigh the alternative printing methods for short run, durable, external projects, as the machinery is not too expensive and the quality of the media is highly rated by The Vinyl Corporation and certainly inexpensive in comparison to aqueous media.
UV Based Flatbed printers
This area of technology is progressing, but the reliability and costing will have to improve to compete with the Solvent Digital Printers, the one to watch which will be dealt with in the next “Enrichment, Information and Advice ” Bulletin will be the LATEX PRINTER.
Other Printing Processes
There are many other techniques and methods to transfer ink onto a substrate from Dye Sublimation, Thermal ink transfer printing, Letterpress – this used to dominate the commercial printing industry, but now it is only really used for business cards and wedding invitations, Flocking, Pad Printing, Intaglio and Thermography, these are really specialist techniques rather than commercially viable printing methods employed in 2017
Digital Printing vs Litho Offset Printing
As previously discussed offset printing utilises printing plates, whereas digital printing does not and therefore the time element of “Set -up” has an attendant cost for offset printing, which makes Larger runs more cost-effective, the more copies that you print – the cheaper they get and with Litho there are at present more ink choices available from metallic’s to Pantone shades.
the overwhelming advantage of using a digital printing process is that set up costs are lower, there is no minimum quantity required, resulting in less wastage and ability to change and make individually numbered prints or individually addressed prints, which is NOT an option with Litho, Also the digital printer can offer a faster turnaround and with the current advancements in technology the smaller, cheaper machines are more responsive, better build quality and offer great price: Performance Ratio.