Wednesday, 29 September 2010

pad printing

Pad printing is a relatively new printing technique that was developed in the 60s and 70s. The process is defined by applying a 2 dimensional image to a 3 dimensional object. It is used on objects that cannot be printed on before being put together such as golf balls, hard hats and thermos flasks. The process allows for printing on 3D objects, but a single print cannot cover the entire object. It is possible to spot colour print using pad printing although the most common method of colour is CMYK. The process is handy in the fact that it can print onto a wide rage of 3 dimensional materials, providing that they can withstand the pressure of the pads(s) during printing. For example, a polystyrene cup would be crushed if you tried to print on the side of it. Also, large quantities can be produced in short amounts of time.

The process works by silicon pads squishing into the object in order to apply the ink in the appropriate places. The diagram helps to make it clearer. Also, the video helps to explain.

A pad printing machine

A metal water bottle with a pad printed design

A champagne bucket with a pad printed design

A hip flask with a pad printed design

A video showing pad printing in action

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screen printing

Screen printing is a very old printing technique that has developed greatly over the past decade to suit modern graphic design practice. It can be a very craft-based method due to its very much human involved element. However, there are industrial automatic and semi-automatic screen printing machines available to suit large jobs. It is not the most common form of printing due to its lack of consistency in quality. However, with industrial methods developed, quality in large quantities has become far more consistent. It is possible to CMYK print on a screen printing bread, although it is more favourable for spot colour methods. This is why it can become more craft based. Some artists and designers create several screens for spot colours to produce hand printed designs that have time and care put into them. The process has an advantage in the fact that you can print onto almost any stock so long as it is flat. It is a popular method for printing on t-shirts. This diagram explains how it works:

During the manual screen printing process (pulling the squeegee to squeeze the paint through the mesh screen)

A close up of the squeegee and paint

A semi-automatic screen printing machine

A semi-automatic screen printing machine in the process

A just finished print on a semi-automatic screen printing machine

Artist for the band Radiohead, Stanley Donwood advocates the process of screen printing in a lot of his work. Here is his his own manual screen printing bed surrounded by his own prints

A Stanley Donwood screen print. Note the layered spot colour that gives a translucent effect. This is an effect achievable in the process simply by layering

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digital printing

Digital printing is the most recent development in printing. It is the only printing method to work directly from a computer - hence 'digital'. It is not often used for mass production - that is, over 500 prints - due to how long it takes to produce a print. Digital printers rely on a system called RIP (Rasta Image Processor) in order for interact with the computer successfully to produce a print. Digital printers print using CMYK colours, however, even though the concept of using spot colour is possible through digital printing, it is a waste of time because of how much it costs to produce the ink, along with many other reasons such as individual colour combinations would be likely to need their own printers. Digital printers can be commonly found around small printers in most towns and cities making them a lot more readily available to the public than other, more specialist printing methods.

There are generally two types of printer. They are inkjet and laser. They both work in CMYK but apply the ink differently. Inkjets work with wet ink in cartridges that are placed in the printer. Ink is applied by the printer head which sweeps over the stock and applies the appropriate ink at the appropriate time as the paper is fed through by rollers:

Inkjet Diagram

A. Pump, B. Ink Sensor, C. Ink Cartridges, D. Print Head, E. Vent Chamber

Laser jet printers work differently. They use toner which is applied to the paper using a technique involving static electricity which charges atoms positively on the paper and the coloured toner making them stick to the paper. Here is a basic diagram of a laser jet printer:

To finish off, here are a couple of images of digital printing in action:

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flexography printing

Flexographic printing is similar to Offset Lithography and Rotogravure printing in the fact that it is a rotary printing method. It relies on rotating cylinders to apply the ink and feed the paper through the printing process. It is different from other rotary printing methods in the fact that it uses plastic or rubber relief plates on the printing cylinder in order to transfer the image to the stock, as opposed to rotogravure, where the plate is etched metal. The rubber plate makes the printing process very versatile which is why it is commonly used for packaging material ranging from toothpaste tubes, to crisp packets, to sheet metal that will go on to be made into cans etc. The process allows for all sorts of stocks like plastics, papers and metals to be printed on. It is a CMYK process meaning that the image passes through 4 separate rolls of cyan, magenta, yellow and key (black) to produce a full colour result. The inks that are used tend to be fast drying in order to facilitate the process. The process can be married with web printing so that a continuous roll runs through the printer. This is handy for long prints such as wrapping paper.

Like rotogravure printing, flexographic printing was developed in the late 19th century and grew in popularity. However, in the 1940s the process was cut down due to the Food and Drug Administration deeming the ink used in the process as unsuitable for food packaging, although it is only until recently (the past couple of decades), that the process has been developed and it has been rejuvenated by been one of the most popular commercial packaging printing processes again.

A Profile Diagram of the Printer Rolls

A Flexography Printing Machine

A Flexographic Rubber Printing Plate

A Flexographic Rubber Printing Plate

A Man Applying A Flexographic Rubber Printing Plate

Rolls of Flexographically Printed Packaging

Crisp Packets Tend to be Printed Flexographically

The Packaging for these 'Olive Bites' was printed Flexographically

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bear good


Tuesday, 28 September 2010

rotogravure printing

Rotogravure printing is similar to offset lithographic printing in that it is as rotary printing process involving rotating cylinders acting like a washing mangle in order to print an image on a piece or roll of stock. The difference to lithographic printing is that the image itself is etched on a metal plate that is actually attached to the roll that is printing directly onto the stock. It is known as an intaglio printing method due to the fact that the design for printing is etched into the metal printing plate. Rotogravure printing tends to work best with thicker stocks due to the leeway available when the etching presses into the stock itself. Examples of rotogravure printing include floor coverings and wallpaper, although paper stocks can also work with the process. It is a CMYK process which involves for 4 separate etchings of the same image that are each individual in their etching depth to match their CMYK values.

The process was developed in the late 19th century and was involved in major production by the 1920s. It has since developed into a world renown printing process. This diagram shows how it works:

Here is an example of a Rotogravure Printing machine:

A finished batch of packaging fresh of the Rotogravure printing process:

This is a piece of packaging that has been designed to follow the Rotogravure printing process. This however, is using 8 process colours in order to create 256 different colours instead of the standard CMYK format.

Ringo Starr has clearly heard of the Rotogravure Printing process! This is his 6th album. Whether the vinyl covers produced at the time were printed with the Rotogravure printing method is unknown. It would be cool if this was the case though.

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ninja vs penguin screen printing

I came across 'Ninja Vs Penguin' whilst generally surfing the internet. They appear to specialise in limited edition lithographic prints. Primarily image based, I take more of a general work-based interest in what I see here. Knowing that this kind of work can be created with offset lithographic printing is great. It's has become important for me to realise that this is a method of printing that artists and designers can use to produce limited edition prints - as has been done here. They are both editions of 300 so lithographic printing was certainly the best choice. Screen printing was an option I imagine, but 300 screen prints can be a bit of a strain! Hence why lithographic printing appears best for the job.

First Kiss

Daydream Believer

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offset lithography

Offset lithography was developed over 100 years ago as a method of mass production of printed items. The method was designed so that each copy of the printed item coming out the printer, would be identical to the other. This made the method suitable for printing newspapers and has since developed to undertake the capabilities of web printing - that is - printing on a giant continuous roll of paper, and it is this method of printing that is so vital in providing John Smith with his paper every morning. The machines can be as big as houses (especially for printing newspapers) and it can only be assumed that they are extremely highly maintained due to their upmost importance in printing the national news every day. As well as this extreme industrial standard of printing, the method is also used for mass production of other printed items such as posters and fliers, and basically any stock that will flow through the printing rolls. However, paper tends to be the most prominent choice of stock.

The process works by rolling 4 'etched' pieces of sheet metal that have the chosen design inked out on them (4 as each sheet constitutes the primary printing colours of cyan, magenta, yellow and key (black)). The process relies on water and oil to determine where ink should appropriately sit on said pieces of sheet metal. The design is inked onto a roller which subsequently rolls it onto a rubber roll connecting with it that finally prints it on the paper. The diagram should explain:

The machines really are huge.

I found this example of a print being made in offset lithography printing format. It is a print by artist David C. Driskell.

David C.Driskell - The Bassist (2006)

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Monday, 27 September 2010