OUGD504- Process/Finish Research

Lithography

Josef Albers, Ascension from the series Graphic Tectonic, 1942, lithography

- Invented in 1798 by German actor and writer Aloys Senefelder

Lithography can be one of the most direct printmaking mediums because images are executed on a flat surface in much the same manner as crayon drawings or watercolours on paper.


-process

A greasy lithographic pencil is applied to a thick slab of limestone, the surface of which has been polished or 'grained'.

The image is then fixed to the stone using a weak solution of nitric acid and gum arabic. The image is then washed out with turps

A thin layer of bitumen is then applied to the surface of the stone to help replenish the greasy deposits of the image. The stone is then rinsed with water.

A thin layer of bitumen is then applied to the surface of the stone to help replenish the greasy deposits of the image.

Then a greasy ink is rolled on. The ink adheres only to the image drawn with the pencil and is repelled by the water-soaked surrounds.

Paper is then placed over the inked surface and a metal or plastic sheet is lowered onto it.

With the aid of a specific press, a scraper is drawn across to transfer the image to the paper.

Offset Lithography 

Offset lithography is a process used for printing on a flat surface, using printing plates. 

An image is transferred to a printing plate, which can be made of a variety of materials such as metal or paper. The plate is then chemically treated so that only image areas (such as type, colors, shapes and other elements) will accept ink. 

Water and ink is applied to the plate. Because of the chemical treatment, ink only "sticks" to the image areas, which reject the water. Areas without images reject the ink. 

The plate is then rolled onto a rubber cylinder applying the inked area, and in turn the rubber cylinder (or "blanket") applies the image to the paper. 

The system is "offset" because the plate does not come in direct contact with the paper, which preserves the quality of the plate.

Grili Type Lithography ABC is a series of 26 risoprinted postcards inspired by old lithography posters.

Digital Printing

Digital printing descibes the process of transfering an image or document stored on a pc or mac onto a printing media such as paper, card or even textiles.

The image is normally automatically split into 4 basic colours - cyan, magenta, yellow and black (printers refer to this as CMYK) and the print engine then prints these four colours overlaying them exactly to reproduce the image on the screen.

These print engines are most commonly found in two basic types; 
the first uses dry toner powder which is fused into the substrate 
the second uses electrostatically charged wet ink which is fired at the paper. 

These basic types are referred to as toner based or inkjet based devices.

This is why for short runs requiring fast turnaround times digital printing is the most effective printing solution. In addition, the flexibility of personalising each and every print with a digital printing press means that for targeted direct mail communication, digital printing is the only cost effective solution.

Screen Printing

The equivalent of the printing plate for the screen printer is the SCREEN - a wooden or aluminium frame with a fine nylon MESH stretched over it. 

The MESH is coated with a light sensitive emulsion or film, which - when dry - will block the holes in the mesh and exposed to ultra violet light. 

The screen is then washed with a jet of water which washes away all the light sensitive emulsion that has not been hardened by the ultra-violet light. 

This leaves you with an open stencil which corresponds exactly to the image that was supplied on the film. 

Now the screen is fitted on the press and is hinged so it can be raised and lowered. The substrate to be printed is placed in position under the screen and ink is placed on the top side of the screen, (the frame acts also as wall to contain the ink ). 

A rubber blade gripped in a wooden or metal handle called a SQUEEGEE (not unlike a giant wind-screen wiper) is pulled across the top of the screen; it pushes the ink through the mesh onto the surface of the substrate you are printing. 

To repeat the process the squeegee floods the screen again with a return stroke before printing the next impression.

Letterpress

How letterpress works: Letterpress printing exerts variable amounts of pressure on the substrate dependent on the size and image elements in the printing. 

-The amount of pressure per square inch or "squeeze" is greater on some highlight dots than it is on larger shadow dots. 

-Expensive, time consuming adjustments must be made throughout the press run to make sure the impression pressure is just right. 

-Major chemicals used in letterpress printing, very similar to those used in lithography, include film developers and fixers, inks, and blanket and roller washes.

There are three different types of letterpress printing devices in use today: platen, flat-bed, and rotary presses. The two most common types of letterpress presses, the unit-design perfecting rotary press and the rotary letterpress typically used for magazine printing.

Traditionally, letterpress printing involved arranging individual blocks of 'moveable type' into a caddy, forming words from the combination of letters. As this type was used to make the print, all the characters were moulded in reverse, and the words had to be similarly arranged in reverse. Images could be included in letterpress prints, but needed to be etched in either wood or metal, making it a time-consuming process.

Many of the typography terms and phrases we’re now familiar with originate from the combination of moveable type and the letterpress process. 'Upper case' and 'lower case', for example, refers to the storage of the different type forms in type cases. 'Leading', the space between two lines of type, refers to strips of lead placed between lines of moveable type to space them further apart.

The finished print surface, constructed from moveable type and image plates, is inked before being applied with pressure to the surface being printed. This results in a clean, sharp imprint, and dependent upon the amount of pressure applied during the print, along with the material being printed onto, a physical debossing impression will be made simultaneously. This debossing impression is part of the appeal of letterpress print, as it adds to the tactile nature of the printed piece.

Relief Printing

Also known as block printing

This is different than letterpress where the image is applied with enough pressure to leave an indent on the paper

The most common form of relief printing is woodcut. 

An ink drawing is made on a wood block. The artist cuts away un-inked areas, leaving inked areas raised. Printing ink is applied to the raised surface and a sheet of paper is laid on the block to take an impression by hand or a press.

other materials used to create the printing block:

-Woodcut, linocut, embossing

Equipment 

There are many different types of ink on the market, and it’s important to test them out to find the best one. Oil-based inks are good because they give the best even coverage and print well on both fabric and paper.

Thermography

Also Known As: 

offset thermography | raised printing | thermographic printing

Thermographic printing is a practical alternative to engraving(copperplate printing) and is more affordable.

While engraving raises the paper surface, thermographic printing raises the image or type. This is achieved by sprinkling powdered resin onto wet ink, then heat-fusing it onto the sheet.

Though a similar look is achieved to die-stamping or engraving, thermographic print will not show the fine details of typography or logotypes.

Standard Thermography 

-is available in a high gloss clear finish which allows the ink colour to show through and gives a smooth raised printed finish. Solid areas have an orange peel effect. It is also available in metallic gold and silver. Thermography adds that special touch when it matters. When used for letterheads, it should be noted that although perfectly suitable for use with ink jet printers or other processes not involving heat, the image will melt if fed through a laser printer or photocopier.

Laserproof Thermography 

-is for those who use laserprinters to output their letters, it is no longer necessary to sacrifice the quality of their stationery. UV cured laserproof thermography is a newly developed thermographic finish that is safe to use. It will withstand the temperatures found in laserprinters and photocopiers without being damaged.

Thermography Common Applications...

Thermographic printing lends itself well to the following print and stationery items:

-Letterheads
-Formal Invitations
-Creating Braille Effect Text
-Diploma and Certificate Printing

Foiling

Varnish 

A varnish is a liquid coating applied to a printed surface to add a clear glossy, matte, satin, or neutral finish. Here are the types of varnishes:

Spot UV Varnish is generally a screen printed process where certain areas of a design are ‘picked out’ and the varnish is applied only to these areas.

UV Varnish Pros:

- can be used to enhance specific areas such as text, logos or images rather than cover a whole page- additional substances can be added to varnish to increases its versatility such as glitter
- can be used in conjunction with a laminate and printed over the top to create a more creative and diverse result
UV Varnish Cons:

- if printed over a crease in a document it will crack in the same way ink does- if printed over text or images will be subject to ‘make ready’ die charges which increases its cost
- due to additional set up required uv varnishing is a longer process than lamination

Emboss/Debossing

Often used in combination with foil stamping, embossing is a process that alters the surface of paper stock or other substrates by providing a three dimensional or raised effect on selected areas. 

The procedure requires the use of two dies: 

-one that is raised 

-one that is recessed

The dies fit into each other so that when the paper is pressed between them, the raised die forces the stock into the recessed die and creates the embossed impression. A specific level of pressure is applied to the dies in order to squeeze the fibres of the paper, which results in a permanently raised area in the paper.

Die Cutting

The term "die cutting" is loosely applied to many types of cutting process but in our sphere of application and activity it applies mainly to the cutting out of shapes from soft or semi-rigid materials in single or multiple layers.

The process itself is, in fact, very simple but the machinery to perform the process has become increasingly sophisticated.

The closest analogy is to imagine a hand-held pastry cutter being pressed by hand through a sheet of pastry. For 'pastry cutter', think cutting die or tool. For 'hand', think cutting press.

The advantages of the die cutting process are speed, accuracy, use of unskilled labour, material saving, relatively low cost tooling.

Tooling

The tooling is commonly referred to as a cutting die, cutting tool, cutting knife or cutting forme and these are available in three main types:

Wood forme - Cutting blade to the shape required is set in a plywood backer.
Strip steel - This is usually a heavier gauge steel, bent to the required shape, possibly with re-inforcing struts.
Forged steel - This is a heavy duty construction where the highest precision is required, usually for long runs and also, usually, for harder materials. It is also the most expensive.