Printing processes

Processes Lithography (Litho) Letterpress Flexography Gravure Screen printing

Lithography History Water and grease don’t mix Toulouse Lautrec drew with a greasy crayon on stone put water on the stone then put ink on stone using a roller The ink would stick to the crayon not the water and when the paper was pressed on the ink would transfer to the paper

Litho today Fast, economic and quality Uses aluminium plates Offsett image on plate transferred to roller which is transferred to paper Diluted oily ink which needs time to dry Sheet fed or web (web means continuous roll of paper) Economical for between 1,000 and 1,000,000 copies Colour broken into Cyan, Magenta, Yellow and Black (CMYK) or spot colours for extra particular colours

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Colour Bars Registration marks Registration marks Check Thickness of ink Registration marks Check printed in the right position Registration marks

Letterpress A letterpress works much like a sophisticated rubber stamp. The raised image area is inked by large rollers and the ink is then transferred directly to the paper sheet. Draw this diagram and add the lables

Letterpress The oldest printing process Relief printing One colour (usually black) thick layer of ink Economical for between 500 and 5,000 copies Limited typefaces available Used mainly for text only - not suitable for half tone illustrations Most often used for text pages of books

Flexography Frequently used for printing on plastic, foil, acetate film, brown paper, and other materials used in packaging particularly carrier bags uses flexible printing plates made of rubber or plastic The inked plates with a slightly raised image are rotated on a cylinder which transfers the image to the substrate. uses fast-drying ink, limited quality can be achieved Economical for between 250 and 5,000 copies using hand fed machinery. Economical for very high volumes (250,000 to 10,000,000) using fully automated machinery

Gravure High quality and expensive Used for high quality photographic images Opposite of relief printing printing plate created with engraved image creating cells of ink colour Ink is spirit based and dries immediately Gravure printing is often used for high-volume printing of packaging, wallpaper, and gift wrap. Although less common, gravure printing may also be used for printing magazines, greeting cards, and high-volume advertising. Economical for between 500,000 and 5,000,000

Gravure Draw this diagram and add the lables

Screen printing This is completely different to other printing processes as it uses a stencil through which ink is forced. The stencil is attached to a fine mesh (originally silk) which controls the amount of ink passing through the stencil Used mainly for T-shirts and unusual shaped plastics Famously used by Andy Warhol Good quality can be achieved as long as images are relatively simple - Cannot achieve fine detail Requires a long drying time

Test 1. 2,000 single colour, good quality, leaflets are required. Which printing process would you consider to be most economical to use? ∏ Offset lithographic ∏ Screen ∏ Photocopy ∏ Gravure

Are the following statements true or false ? 2 The ink is held below the surface of the plate during gravure printing. True False 3 Water is used to print with when lithographic printing. True False 4 Red, yellow, blue and black make up process colours. True False 5 A fine mesh controls the flow of ink in screen-printing. 6 Letterpress gives the best quality print for photographs. 7 Flexography is the most suitable process for printing on to plastic film.