If a printer hasn't mentioned ultraviolet (UV) inks to you yet, it won't be long.

That's because printers are excited about the considerable benefits that printing with UV offset printing inks can afford their company, including faster turnaround time (UV inks take seconds to dry on press) and lower environmental impact (UV inks don't use solvents and produce lower emissions than conventional inks). Although these advantages are real, they don't mean you should start using UV inks on every project.

UV inks aren't the same kind of inks used in traditional printing. Rather, they are dual-state substances: solids that remain in a liquid form until exposed to UV light. The ink is applied during the printing process on a press, in the same way as conventional ink, but then the ink is dried within seconds by lights mounted on the press.

Since the UV printing ink dries as the sheet passes under the light, the sheet is ready for the next production step as soon as it comes off the press. With conventional inks, the printer must allow the sheet to dry completely, which often means overnight, so using UV inks allows the printer to get more work done in less time.

Some conventional printing inks contain chemical solvents -- in some inks, up to 70 percent. As conventional inks dry, the solvents evaporate and volatile organic compounds (VOC) are released.

These compounds are considered environmental hazards, and some localities have passed laws to limit the amount of VOC released into the air or the maximum amount of VOCs in products. If a printer can eliminate solvent-based inks from the workplace, he can lessen an environmental hazard and in doing so may also comply with local regulations.

Printing is a process of impressing letters, texts, pictures, images or figures on paper, cloth, plastic and other material. Particularly with ink on paper using a printing press. You can see this medium everywhere. It is used in news paper, brochures, business cards, invitations, magazines, books, etc. Here are the two most commonly used type of printing:

Offset Printing ink. For working on a wide range of printing surfaces including paper, cloth, wood, leather, metal, and plastic. If you use the Pantone® Matching System, offset printing will give you the best color match. Modern offset printing inks presses use computer-to-plate (CTP) systems, shortening the work flow and reducing cost via elimination of the film.

Advantages of Offset Printing:

1 Provides excellent quality prints

2 Best suited for high volume printing since the unit cost goes down as the quantity goes up

3 More flexible when it comes to unusual printing surfaces or sizes

4 Uses CMYK (also known as Process or Full Colour) and Pantone spot colour (PMS)

Digital Print. For more accurate sheet counts and cheaper low volume printing. It also gives a more accurate proof since you see an actual sample of the printed piece. Accurate color proofing in offset printing can prove to be expensive. Variable Data Printing is a customizable digital printing. You can print variable text or images that is unique or personalized in some way for each sheet that comes off the press.

Advantages of Digital printing:

1 Short turnaround

2 Lower cost for low print runs

3 Less waste because of fewer variations

4 Can use both CMYK and RGB

The most common kind of offset printing is derived from the photo offset process, which involves using light-sensitive chemicals and photographic techniques to transfer images and type from original materials to printing plates.

In current use, original materials may be an actual photographic print and typeset text. However, it is more common — with the prevalence of computers and digital images — that the source material exists only as data in a digital publishing system.

Offset litho printing on to a web (reel) of paper is commonly used for printing of newspapers and magazines for high speed production.

How ink is transferred from the ink duct to the paper has several steps.

1 Offset printing ink duct roller delivers ink from the ink duct to the ink pyramid.

2 The drop roller transfers ink from duct roller to distribution roller. It is never in contact with both rollers.

3 The distribution rollers evenly distributed the offset printing inks. The first distribution roller picks up the ink from driving rollers, and the last distribution rollers transfer the ink to the form rollers.

4 The transfer rollers transfer ink between the ink-absorbing and ink-delivering driving rollers.

5 Driving rollers roll against the distribution rollers and either absorb or deliver ink, depending on their placement.

6 Ink form rollers transfer ink from the last distribution rollers on the printing plate.

7 The printing plate transfers the ink to the paper.

Offset printing, also referred to as offset lithography, is a type of printing process used by virtually all large commercial printers. It is called offset, because the offset printing ink is not directly pressed onto the paper, but is distributed from a metal plate to a rubber mat where it is then set onto the paper.

Offset printing can be done on a web printing press, one that use huge rolls of continuously fed paper, or a sheet fed press that, as you would expect, uses sheets of paper. Both types of presses produce printed materials that can be cut to size after printing. Offset printing uses all of the latest technology in printing, including computers that aid in design. Computers are also used to generate instructions for the mixture of offset ink colors as well as their distribution to the paper.

Offset printing works because water and the inks used in the printing process do not mix. The images to be printed are created on the computer and then "burned" onto metal plates using a chemical developing process similar to photography. The metal plates are dampened with water which adheres to the areas without images. The ink is added next, one color at a time, where it sticks to the areas with images. The most modern systems use a direct-to-plate system in which the images are burned directly to the metal plates; the omission of a secondary step saves time and money.

The colors used in offset printing are usually Cyan, Magenta, Yellow and Black, represented with the letter K (CMYK). Note that K is used to represent black to ensure that there isn't any confusion with blue. Different percentages of each of these four colors create virtually every color used in offset printing. There are color matching systems, such as the PANTONE® system, that allows print buyers to see the color. The code for that color can be entered into the offset printer's computer and it will calculate the percentages of each color to be used.

The technology behind offset printing allows large volumes of printing to be completed quickly and without any variations in ink distribution. The final printed materials produced through offset lithography also dry quickly, keeping the production process moving smoothly from the printing to the finish work of cutting and binding materials.