CATALOG PRINTING PROCESS

Web Press: A web press is an offset press that uses a roll of paper rather than sheets of paper. The use of a roll of paper allows for faster printing. There are two types of web presses - heat-set and cold-set - see below.

Heat-Set Web Press: A heat-set web press is the standard catalog and magazine printing press. This press has a heating unit that dries the printed ink as it exits the press. This allows the press to print at high speeds on coated papers such as gloss. This press produces brilliant, crisp photo reproduction for catalogs. Heat-set web presses are very large, complicated presses that require several people to operate and setup. It is only reasonable to use this type of press for print runs of 10,000 copies or more and in increments of 8 pages, preferably 16 (a full signature). 99% of all mail-order catalogs are printed on this type of press.

Cold-Set Web Press: A typical cold-set web press does not include a heating unit so the printed ink must air dry and therefore can only print on uncoated papers producing a somewhat dull, blurry photo reproduction for catalogs. Cold-set web presses are smaller and simpler than heat-set web presses, costing less and requiring less setup time. Therefore it is a good press for very small quantity catalog print runs starting at 1,000 copies. Once the quantity reaches about 15,000 to 20,000 however, the greater speed of the heat-set web press will begin to be less expensive.

UV Ink Cold-Set Web Press: This rare hybrid of the cold-set web press uses high intensity ultra violet energy to cure ink on the paper. UV is environmentally friendly and can be used on a variety of paper grades and types from newsprint to gloss coated book stocks. Because it can print on gloss or coated paper and still has the lower cost and setup time the UV Ink Cold-Set Web Press is an excellent press for very small quantity catalog print runs starting at 1,000 copies. Once the quantity reaches about 15,000 to 20,000 however, the greater speed of the heat-set web press will begin to be less expensive.

Sheet-Fed Press: As its name implies this press is a traditional low volume press that prints on pre-cut sheets of paper. Because of its more precise printing method a sheet-fed press produces the sharpest printing of these three press types. It can print on a wider variety of paper weights. However, because of its slower speed it is the most expensive of print methods, and is generally only used for small print runs or job requiring the best printing.

Useful Links

1. How Offset Printing Works - http://computer.howstuffworks.com/offset-printing.htm
(Printing is a fascinating process involving huge high-speed machines, 2,000-pound rolls of paper, computers, metal plates, rubber blankets and sharp knives. In this article, we'll look at offset lithography, the most commonly used printing process, and detail the three production steps: pre-press, press run and bindery.)

2. The Creative Process - http://computer.howstuffworks.com/offset-printing1.htm
(Every print piece starts with the creative process. Writers, editors, graphic designers and artists are the initial step in the creation of magazines, newspapers, brochures, flyers, catalogs and other print pieces.)

3. The Printing Process - http://computer.howstuffworks.com/offset-printing2.htm
There are nine main types of printing processes:
offset lithography - what we are exploring in this article
engraving - think fine stationery
thermography - raised printing, used in stationery
reprographics - copying and duplicating
digital printing - limited now, but the technology is exploding
letterpress - the original Guttenberg process (hardly done anymore)
screen - used for T-shirts and billboards
flexography - usually used on packaging, such as can labels
gravure - used for huge runs of magazines and direct-mail catalogs

4. Step One: Pre-Press Production – http://computer.howstuffworks.com/offset-printing3.htm
(Before the job can be printed, the document must be converted to film and "plates." In the case of How Stuff Works Express, film negatives are created from digital files. Images from the negatives are transferred to printing plates in much the same way as photographs are developed.)

5. Step Two : The Press Run - http://computer.howstuffworks.com/offset-printing4.htm
(The printing process used to print How Stuff Works Express is called web offset lithography. The paper is fed through the press as one continuous stream pulled from rolls of paper. Each roll can weigh as much as 2,000 pounds (1 ton). The paper is cut to size after printing. Offset lithography can also be done with pre-cut paper in sheetfed presses.)

6. Step Three: Bindery - http://computer.howstuffworks.com/offset-printing5.htm
(The bindery is where the printed product is completed. The huge rolls of now-printed paper are cut and put together so that the pages fall in the correct order. Pages are also bound together, by staples or glue, in this step of the process.
In the case of How Stuff Works Express, a machine called a stitcher takes the folded printed paper (called press signatures) and collates them together. Then stitches (staples) are inserted into the signatures, binding them together.)
Howstuffworks.com, How offset Printing Works by Mark Mine.

For complete list of offset printing glossary, go to Printing Glossary