Print Workflow


Offset

The most common form of commercial printing, offset is a printing process in which a printing plate is made; then it is mounted onto a cylinder, rolled in a mixture of ink and water, and then offset onto a blanket, which in turn rolls over paper.

This method of printing is by far the most common and the option you will choose repeatedly to address the majority of your printing requirements. Build references or resources of stock samples as well as ink catalogues, and include chip books or fans, which will assist you with your production choices. It is also helpful to have a good understanding of bindery and finishing options. The following is an overview of the offset method.

Sheetfed Versus Web

There are two categories of offset: sheetfed and web. Sheetfed sends cut sheets of paper through a printing press, whereas a web press sends paper through a press from giant rolls of paper, which are later cut.

The applications for offset are numerous. Almost all examples in this book could be accomplished with offset, sheetfed printing. Publications that are typically printed on web presses include newspapers, books, and magazines, which are typically printed in large quantities. This is a more economical method of printing because the run lengths are long, thereby decreasing the cost per piece. Because the paper is not precut, the cost for this resource is lower. The more impressions you can get from a plate, the less expensive each impression is. Web presses can print on both sides of paper at the same time as the web (rolled paper) runs through the web pressagain an economization.

Note

When referring to quantities in printing, you sometimes might hear the term run length. Short runs versus long run lengths also contribute to the decision regarding sheetfed or web press.


Chemistry

Offset printing involves the creation of printing plates that have oleophilic, or oilattracting, areas (the image) and hydrophilic, or water-attracting, areas (the nonimageable area). The printing press uses a combination of water and ink, and the chemicals then migrate to the appropriate areas on the plate. There is already some moisture in the paper itself, which actually assists in the printing process; however, too much moisture in the paper will ultimately cause problems as the paper eventually cures or dries and shrinks.

A lot of skill is involved in getting the chemistry or balance between water and ink just right. So, unlike any other printing process, achieving optimum color requires several passes before the press operator pulls a press sheet he is satisfied with. The goalaside from managing a schedule, mounting plates, mixing and managing chemistry, loading paper, and maintaining the pressis to come as close as possible to matching the proof you signed.

Proofing

Sometimes the proof you signed is made from the same films that made the printing plate the press operator is using. The benefit of this method of proofing is that the plate and the proof are made from a common source, which should result in the printed piece more closely matching the proof. The downsides to this type of proofing are cost and time. Now that more than half of all commercial printing plants in this country are direct-to-plate (a method in which the printer can send your file directly to plate, without having to image film), a proof made from film is not an available choice because no film has been made.

Digital proofing has emerged hand in hand with direct-to-plate. The same file that generates the plate generates the proof. This is a great economy of time and money. The trick is to get the digital proofing device to image or create color to match the printing plate production. When consistent color can be achieved to match digital proof to plate, everyone wins. The printer achieves economy of the manufacturing process and therefore the customer wins, as well.

As we've discussed previously in this book, printers can employ a variety of proofing technologies, and there are pros and cons to each. Just remember that pleasing color can be achieved at lower resolutions (twice your linescreen), whereas most of us would like to see crisp, clean type, which is achieved at higher resolutions. You will ultimately get this from your printing plate, but it might be difficult to achieve depending on which digital proof option you choose.



Adobe InDesign CS2 @work. Projects You Can Use on the Job
Adobe InDesign CS2 @work: Projects You Can Use on the Job
ISBN: 067232802X
EAN: 2147483647
Year: 2003
Pages: 148

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