Design Context

Printing processes.

(Offset) lithgography is the most common used method of printing. It's a process that has gone reletivly unchanged since the late 1800's. The only thing that has changed is the technology which, over the years has become more sophisticated.
As explained in the video (below,provided by lorenzo) we come into contact with litho prints in our everyday lives. So much infact that we take the process for granted.



Like every print process, everything printed by litho process has to be considered.
In addition to size, page count, colour coverage and quantity the estimator evaluates press time, special paper order, labour and shipping costs. The estimator must to this efficently to get the best price. Each file (Email, ftp or send a CD with the artwork on it. The files are then inspected carefully to make sure they have all the fonts, colour palettes and high resolution graphics. A sample is then given to the client so they know what to expect. This is known as a proof. Once aproved by the client, the proof gets sent back to the prep department. The computer then separates the colours into PMS colours (Pantone) 4 colour process colours -  Cyan, Magenta, Yellow or Black (CMYK) Using different percentages of these colours the printer can print any colour the client wants. Each colour is then etched into thin, aluminum plates which are then taken to the press to print the job.

A LITHO PRINTER.

The press is comprised of four separate presses, one in each tower. The four plates are then wrapped around a plate cylinder in each of these 'towers'. The basic principle of offset is that you HAVE to have ink and you HAVE to have water to make it work.
The plate is put into the printing press (offset). You have to have the right balance of water and ink to fill in the image area but keep the none image area clean. The image is transferred as a reverse image from the plate to a blanket (rubber pad) which is locked tightly around what is referred to as the blanket cylinder.
Below that coming from the printing press at high speed (5000 - 11000 sheets an hour)
you have the paper which is moving from unit to unit in order to pick up the ink and create the full image.
Below that is an impression cylinder. The cylinder squeezes the paper against the rubber blanket at just the right pressure, to pick up the ink and keep it moving along whilst keeping the image smooth. Once the paper has recieved its ink (4 colours),
it goes through an infra red dryer which heats up the paper. This helps set the ink so it's ready to print the other side.
The press operator constantly inspects the sheets to make sure each layer of ink lines up perfectly to give a perfectly registered image - tower to tower.