Studio Seminar 28th September: Print Production

Everything mentioned in the seminar was things that I never knew and I'm glad that the different types of printing methods were explained as the only printing processes I know are at the digital print rooms and screen print. I think the understanding behind print and the processes are important as a Graphic Designer because from this seminar and other workshops there has become a list notes that gives me the extra professional knowledge when considering printing processes. Below are a list of the different printing methods that I learnt about in the seminar:

Lithography

Lithography was developed in 1796 by a Bavarian author Alois Senefelder as a low cost method of mass production printed items. The method consists of 4 etched sheets of metal (Cyan, Magenta, Yellow and Key - Black) rolled using ink and water into rubber rollers then printed onto stock.

Explanation of the Lithography process because I found it hard to explain but I hope this will help.

Old photograph at a Printing firm of the scale that printers come in. They are used for mass production for example newspapers, cards, flyers, letterheads, postcards ect

Rotogravure

Rotogravure was from the 1920's/30's to mass produce items such as photographs cereals boxes, newspapers. The process is similar to the offset lithography however the etched metal sheet is wrapped around a cylinder which prints straight onto the stock. This is good for printing rolls of stock non - stop as the cylinder can keep on printing continuously. It is a CMYK process each colour having it's own etched metal sheet. However it can be used for spot colours as well.

Picture above - Explanation of the process of Rotogravure printing

Picture above - A picture of the Rotogravure printers

Video above - Quick American video to sum up Rotogravure printing

Flexography

Flexography printing is similar to the two above Lithography and Rotogravure printing because they are all rotary printing methods. Instead of using etched metal sheets like Rotogravure printing Flexography uses rubber or plastic sheets instead which means it is more versatile which can be applied to packaging material such food packaging products. It is basically an updated version of letterpress that can be used for printing on almost any type of substrate including plastic, metallic films, cellophane, and paper. It is widely used for printing on the non-porous substrates required for various types of food packaging (it is also well suited for printing large areas of solid color).The ink is controlled in the flexographic printing process by the inking unit. The inking unit can be either of Fountain Roll system or Doctor Blade System. The Fountain roll system is a simple old system yet if there is too much or too little ink this system would likely not control in a good way. The doctor blade inside the Anilox roller uses cell geometry and distribution. These blades insure that the cells are filled with enough ink. It consists of four different stages CMYK each having its own plastic sheet resulting altogether to the final outcome.

A Visual explanation of how the Flexography process works.

Photograph taken from studio workshop - Flexography sheet

Photograph taken from studio workshop - Flexography close-up

Photograph taken from studio workshop - A magnified photograph of the outcome from using the Flexography printing process - Nestle Ice cream food product. Not sure you can make it out from this photo, but you could see where the plastic stock has been pulled away from the Flexography printing cylinder leaving tiny white marks.

In-Line Press: Like the stack press, the in-line press has separate printing units for each color and each unit has its own impression cylinder, but they are arranged in a horizontal configuration just like a rotary offset press. Because of the distance between the printing units, problems with print registration can occur. Tension control equipment is used on the press to hold proper registration between multiple colors. The wider in-line presses are used for printing large items such as corrugated cartons and smaller width webs are used for printing pressure sensitive labels at high speeds.

Stack Press: The stack press has separate printing units stacked vertically and each printing unit has its own impression cylinder. This was the first type of press developed for flexography. It is difficult to hold registration between multiple colors printed on stretchable substrates using the stack press, even with web tension controls. It is best suited for heavier gauge substances, such as thick paper products, that will not stretch or for applications that do not require good registration.

Digital

Digital printing is the latest process of printing and is called digital as it is sent straight from the computer to print. The process is time consuming compared to other printing methods so that is why the mass of prints are usually quite small - 500 flyers example. Digital printers use CMYK but can also include a stock colour. There are two main types of digital printer, Inkjet and Laser printers. Different from most other printing processes the digital printers can be found in most areas which are available to the public.

Above - Diagram explaining Laser print process

Above - Diagram explaining the Inkjet print process

Above-Example of digital printer in action

Screen Printing

Screen Printing a more traditional method of printing but recently has evolved into semi-automatic screen printing machines. The screen printing consists of four layers of CMYK but can be available for spot colours which is popular for designers and artists for more delicate and quality prints.

Above - Quick visual explanation of the Screen printing process

Above- Screens for printing mass quantities to save time-Semi-automatic

Above - Computer Arts Competition -

Design and screen print a T-shirt

Multiple shows you how to create a piece of digital artwork in Illustratorand transfer it to a T-shirt using screen-printing techniques

http://www.computerarts.co.uk/tutorials/premium_content/2d__and__photoshop/design_and_screen_print_a_t-shirt

PAD

Pad printing was originally developed and used in the Swiss watch industry to print watch dials and car instrument dials using manually operated machines with pads made from gelatine, and using slow drying oil based ink. In the late 1960s the process was further developed in Germany with the introduction of silicone rubber pads and mechanical machines; with the help of Wiederhold (now Coates Screen, part of Sun Chemicals) a range of pad printing inks were developed to allow the process to print onto a wide range of products and materials.

Pad printing is an indirect photogravure process. An image is etched into a flat printing plate and ink is flooded and doctored across the surface leaving ink only in the etch. A silicone rubber pad then presses down onto the etched plate and picks up the ink, which due to solvent evaporation has become tacky. The image is now on the surface of the silicone pad. Silicone rubber does not allow ink to penetrate its surface and therefore when the pad presses down onto the product to be printed it releases the ink as a clean film. The range of inks and solvents used enable the inks to adhere to the surface after releasing the ink the pad is then clean and free to repeat the process. Because such a wide range of inks are available almost any material can be printed and due to the flexibility of the silicone rubber pads uneven, curved and awkward shaped surfaces can be printed. As the ink is quick drying, pad printing is capable of 'wet on wet' printing and high quality multicolour designs can easily be achieved including four colour process. The more recent development of closed cup machines has made the process 'cleaner' and enabled the process to become more user friendly and automated. Ideal for printing from the computer onto 3D products.