Flexography

This print process is used for printing thingd that are generally quite difficult to print on, such as foils and plastics, mostly food packaging.

A rubber sheet is made using a mirror image and then wrapped around a cylinder where is prints ink directly onto the substrait. A flexography press has it's advantages over other rotary printing methods as a wider range of inks can be used with it.

Rotogravure

The images are etched onto copper sheets instead of aluminium like offset litho and then wrapped around a cylinder. It works upside down in comparison to offset litho, with the impression cylinder on the top instead of the bottom. There is also one less cylinder involved, cutting out the 'blanket' cylinder all together. Because this cylinder is missing, the image etched onto the copper plate is a mirror image to ensure that it prints the right way up on the paper/plastic/fabric.

The vast majority of rotogravure printers are web fed, and the few sheet fed ones that exist are classed as a 'speciality market'. One example of roto printing would be newspapers. Rotogravure presses are the fastest printing process and can print onto very wide substraits, such as vinyl flooring.

Offset Lithography

Offset litho uses etched aluminium plates wrapped around a cylinder which then transfers ink onto a rubber 'blanket' cylinder and from there onto the paper/plastic/fabric ect.

This process can either be sheet fed or web fed, web being huge rolls of paper used for very large print runs.

This process uses CMYK colour process and has a different part of the machine for each colour separation, therefore an image is printed using four different etched aluminium sheets.

Screen Printing

A screen is made of a piece of porous, finely woven fabric called mesh which is stretched over a frame of aluminium or wood. Originally human hair was woven into screen mesh but these days mesh is made out of man-made materials such as steel, nylon, and polyester.

Areas of the screen are blocked off with a non-permeable material to form a stencil. A negative of the image is made so that the ink will go where there is no image space. For example, All white spaces will be filled with black to form a reverse image.

The screen is then placed atop paper or fabric. Ink is placed on top of the screen and a bar/piece of wood is used to spread the ink across the mesh and the design.

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Pad Printing

"Pad printing is a process that can transfer a 2-D image onto a 3-D object"

This process is used for printing onto objects that would otherwise be impossible to print on, such as pens and keyboards. A silicone plate is used to press the image into the surface and because the plate is flexible, it can be applied to almost any shaped surface.

Digital Printing

Digital printing is the reproduction of digital images on a physical surface. It is generally used for short print runs, and for the customization of print media.

The process differs from lithography, flexography, gravure, and letterpress printing in several ways:

-Every print can be different, because printing plates are not required, as in traditional methods.
-There is less wasted chemical and paper, because there is no need to bring the image "up to colour" and check for registration and position.
-Because there is less setup, it is useful for rapid prototyping, and cost effective for small print runs.

This is the most popular type of print process as anybody can have a digital printer in their house. Print proofs are not required and unlike most print processes, the ink sits on the surface of the paper and dries there and there is far less wastage.