Last modified on 14 October 2010, at 19:59

Printing

PositionsEdit

A printing broker is in charge of coordinating projects. A graphic designer creates designs and artwork for a project.

CopyrightEdit

According to intellectual property laws, software (including fonts) isn't actually owned by the person who buys it. The purchaser is paying for a license to use the software.

Choose contracts carefully. Make sure that printers "work for hire" so that you retain copyright to the work. If you would like to retain work products from a designer or printer for later use, negotiate this point before work begins. "Work for hire" is work that is created by, for example, a designer, but done so with the express understanding that it is exclusively the property of the client. Paying for work to be performed does not constitute "work for hire." A job cannon be "declared" as a "work for hire." This is a specific legal definition and the terms of "work for hire" cannot be assumed unless:

  1. the job performed fits within a narrow range of possibilities, such as work by a full-time employee or similar or
  2. the worker creating the work is supplied with the "materials and methods" to perform the work as well as specific directions on how to do the job and (typically) the location to work or
  3. the worker signs a contract agreeing to create material on a "work for hire" basis.

Obviously, given the large number of factors involved, a contract is the safest way to assure that work that you hire performed is yours and yours alone.

PlanningEdit

Questions to ask during a project's planning phase:

  1. What is the project's purpose?
  2. Who is your audience?
  3. How will it look?
  4. How will it be used?
  5. How will your audience be reached?
  6. When do you need it done?
  7. What quantity and quality do you need?

One popular strategy is to start at the end of a project, and work backwards. In other words, conceptualize what you want the end product to be, and then figure out the steps to get there.

Prepress is the "creation" to "production" stage. It involves word processing, illustration, and image-editing programs (raster or vector-based).

QualityEdit

GradesEdit

One of the most important steps to a successful print job is determining the right grade for your job. The determining factors are quality, money, and type of job. For instance, items that have a short "lifespan" (such as a promotional poster or flyer) are typically printed on basic or good grade. Everything in a package should be the same quality.

Remember to save all project files for future use.

Basic

Basic grade uses toner, not ink. It is usually only one or two colors, for cheap, throwaway items like flyers. It is inexpensive and low quality.

Good

This grade can be made at a print shop (not a copy shop). It may use toner or ink. Used by magazines like Time and Newsweek.

Premium

This is the grade for "perfect" prints, used for publications that depend on high-quality color (ie, National Geographic).

Showcase

Showcase is top-of-the-line printing, suitable for high-quality art books.

Legibility is the contrast between print and background.

Halftone art causes fine lines to disappear.

ResolutionEdit

Resolution is measured in various ways, depending on the device. Printers use lpi (lines per inch) and dpi (dots per inch), while computer monitors use ppi (pixels per inch) according to the paper size.

Using color printingEdit

The cheapest type of printing remains black ink on a white or colored paper stock. However, four-color process printing has become more affordable in recent years. Specifically, if your color printing job is fairly typical in size, paper stock and quantity, you can take advantage of economies of scale by using a "gang printer" who specializes in printing with process inks on large format presses, combining several print jobs onto a single sheet. This sheet is later cut to produce different jobs for separate clients. This type of process printing is often cheaper than printing a job with solid color inks (say black, maroon and yellow solid ink colors).

Color ModelsEdit

The RGB (Red Green Blue) color model is an "additive" color model. All colors are a mixture of these three hues, mixing 100% of all three colors produces white light and the absence of light leaves black (darkness). The term "additive" refers to the fact that adding color (light) produces a result (a specific color or image). Monitors and most scanners are RGB devices. Most inkjet printers are also RGB devices (despite some having ink sets that may resemble CMYK inks.)

The CMYK (Cyan Magenta Yellow blacK) process color model is used by professional printers. This is subtractive color method. In this system, black is theoretically composed of all colors, and white is the absence of color (paper-color). Cyan, magenta and yellow, mixed at full strength, do not produce black. This is a limitation of the pigments used. The closest result is a dirty brown, so black is added as a fourth "color" to allow for a full range of colors to be expressed and to bolster sharpness and contrast of the image.

Image setters are specialized printers that produce very high resolution output. Typically they are CMYK devices. They can print separations on film which are then used to produce printing plates. Or you can send directly to plate with the new Computer-to Plate technology.

Color TipsEdit

Since color is dependent on light, an object which is one color under one type of light will be a different color when viewed under a different type of light. This phenomenon is metamerism. Some types of light are fluorescent (which is greenish), incandescent (yellowish-orange), and natural (which has a 5000 Kelvin color temperature).

Neutral grey is the best background to view another color.

Color quality, like print quality, depends on the type of publication. "Pleasing" color is used for newspapers, and is the standard for desktop publishing. The next levels are "match" color (used for magazines) and "match original" (used for calendars).

TerminologyEdit

The gamut is the color range available to a device. A palette is a set of colors. Chroma refers to the saturation of a color. Value is the tint or shade of a color.

Temperature is the warmth or coolness of a color. Relatively cool colors are violet, blue and green, relatively warm colors are red, yellow, and orange. Grey or beige are "neutrals", and are considered neither warm nor cool.

Printing techniquesEdit

The two major ways to print color are process printing and spot color printing. Process creates colors by printing very small colored dots. Spot color printing uses solid color inks that are either purchased premixed or mixed from base color inks using specific formulas to match the desired spot or solid color. Spot color printing is also used when a job calls for unusual colors like fluorescent or metallic inks. A spot color is usually specified to print a company logos or proprietary material, although it often will be combined with standard four-color process printing, making the spot color a "fifth" color. This combination can be expensive to produce, although it is common in jobs created for corporate clients.

PhotosEdit

When testing prints, view under "standard conditions" (that is, the type of lighting, etc. you expect to be in the environment where your finished project will be viewed).

Interpolation is a technique that computers use to increase the resolution of a photo. For example, if a digital image happens to have a resolution of 100 pixels per inch, interpolation can be used to increase the resolution to 200 pixels per inch. However, in doing so, four pixels are generated with the data from a single pixel, causing serious image degradation. Some advanced processing technologies, available, for example, in commercial plug-ins for use in Photoshop, can help mitigate the damage to the image. However, the results will not equal starting with an image with sufficient resolution in the first place. In short, interpolation produces sub-standard results in professional terms. Avoid it when you can.

QualityEdit

Halftone

This technique is used for black-and-white photos. It uses one screen.

Duotone

This technique uses two screens for two colors (typically, black and a color). One screen is used for highlights, and the other for shadows.

Separation

This technique uses four screens (cyan, magenta, yellow, and black) to create a wide variety of colors. If the registration of any of the screens is off, the photo will get a cast.

High fidelty

A method using 5-8 halftones.

File TypesEdit

  • PICT -native Apple Macintosh image format until the advent of Mac OSX when it was replaced with PNG and PDF formats
  • TIFF -(Tagged Image File Format) - Contains bitmap images, and supports color separations.
  • EPS -(Encapsulated PostScript) - may contain both bitmap & vector images; can only be cropped or scaled. This format is often used for color separations.
  • JPEG - Joint Photographic Experts Group (lossy)
  • DCS - Desktop Color Separations
  • PDF - Portable Document Format
  • GIF - 8-bit

DevicesEdit

ScannersEdit

Scanner quality is measured in spots per inch (spi). (Digicams use the same measurement.) To ensure a good quality, make sure that pictures are scanned at 1.5 to 2 times the lpi of the finished product.

A scanner's density' (DMax) ranges from 0-5 (with 0 being low density). Most models are between 0 and 3 DMax.

PaperEdit

Paper is usually made from trees. After a tree is cut, debarked and chipped, it can be processed many different ways to make different kinds of paper. It is pulped for newsprint and bag paper. To make writing paper, it must be processed with chemicals. It is calendared (pressed) to make it smooth.

Categories of paper are defined by use (fine, industrial, or sanitary paper), printing method (sheet or web), or pulp content (groundwood, used for newsprint and paper bags, or free sheet, used for writing paper).

TypesEdit

Bond is the most common writing paper. It is standard printing paper, and is more transparent than book or text paper.

Uncoated book is used for books and newsletters.

Coated book is used for textbooks.

Text paper (short for "texture") is used for brochures.

Cover is very thick paper used for paperback book covers and postcards.

AttributesEdit

Paper is rated from I-5 (coated) to A-E (uncoated).

The rest of choosing the right paper depends on aesthetics. Does it have the right look and feel? What kind of texture is good? What level of whiteness do you want? Paper comes in many off-whites, and there are no standards for color. Colored paper is more expensive, and the price goes up the darker the shade is.

Brightness of paper is a measure of its reflectance. Brighter paper creates contrast, but may contribute to eyestrain. Opacity ranges from 1-100%. Most papers are 80-98%.

The grain of a piece of paper can be determined by getting the paper wet and seeing which way it curls. If the sheet curls along the long edges, the paper is "grain long"; if along the short edges, it is "grain short." This is denoted by marking a line under the dimension that the grain follows (for example, 8.5 x 11 would be grain long letter paper).

The paper's weght determines cost. It is sold by "basis weight", which is how much one ream (500 sheets) weighs, in pounds, when cut to 8.5 x 11 inches (21.6 x 27.9 cm). For example, bond paper is 20# weight, since one ream of letter-sized bond weighs 20 pounds.

Caliper is paper thickness, and is measured in points. One point = .001 inch. (This is a different point than the measurement used in typesetting. A typesetting point = 1/72 inch.)

Dot gain is caused by the matte quality of paper. Dots spread as they are absorbed by the paper. The less absorbent the paper is, the less the dots will spread. Glossy paper has low dot gain; this is why higher quality photos are printed on it. (Another factor in dot gain is the ink used. Soy ink has lower dot gain than petroleum-based inks, but takes longer to dry.)

InkEdit

The three types of ink are printing ink (a solid), writing ink (a solution of dye), and toner (a mixture of liquid and solid).

Printing ink, like paint, is made of pigment and binder. It may also contain agents to speed drying and prevent scuffing.

The four ways ink can dry are by absorption, oxidation (exposure to air), evaporation (exposure to heat), and from exposure to light.

Two important attributes of ink are viscosity and tack. Viscosity is a measure of flow. Ink that flows easily has a low viscosity. Tack is a measure of stickiness. Inks that have higher viscosity have greater tack. The faster a press is, the higher the tack should be.

PressEdit

Once the job has been fully planned, a proof can be made up for evaluation. This is a preview of the final product, and a vital step in the project.

Plates are used for some types of printing. Light is passed through a film negative to make an impression on the light-sensitive plate material, such as aluminum or plastic.

PlanographicEdit

Planographic printing uses a flat surface. It uses areas marked off by oil and water to transfer an image. The most popular usage of this process is lithography. The term comes from two Greek words---litho (stone) and graph (writing). (Originally, the plates used were made of limestone.)

Anti-offset powder is used to hasten drying. The ink has a high viscosity and tack. Since it's oil-based, it takes about four hours to dry, and the machine's rollers have to be cleaned after printing. Only uncoated paper can be used.

Problems that arise in planographic printing include moire patterns (from misalignment), ghosting (not enough ink), hickies (particles stuck in the rollers), setoff (ink's too wet), scumming (not enough water), and picking (ink's too tacky,or high print pressure.).

IntaglioEdit

Intaglio is an expensive process using an engraved plate (such as a rotogravure).

Gravure is the process used to make US dollar bills. It uses quick-drying, low viscosity ink.

ReliefEdit

Relief is the opposite of intaglio: the printing area is raised. Simple examples of relief printing are rubber stamps and typewriter keys.

Flexography is one method of relief printing. It uses rubber plates wrapped around a revolving cylinder to create the impression. An anilox roller picks up ink and transfers it to the printing roller. This method is often used to for package printing, such as food bags and boxes, owing to the processe's ablilty to deal with difficult materials such as flexible roll plastics (think of heavy plastic wrap). Common problems with flexographic printing are halos (caused by too much pressure between the plate and the substrate) and voids (not enough pressure). Art meant to be printed on a flexographic press must be mechanically stretched in the direction of the material feed to counteract the distortion of the printing plate as it wraps around the cylinder.

Letterpress Uses metal type either on a flat bed or mounted on a cylinder. The raised areas are inked and the paper is placed in direct contact with the type. At one time most newspapers where printed with letterpress. One of the last major newspapers to switch to ofset lithography was the New York Times. For additional information see the "Pocket Pal" from International Paper Company

GravureEdit

Gravure printing is an intaglio method of printing in which the printing areas are lower than the surface of the printing plate. The plate is coated with ink and the flat surfaces are scraped clean, leaving ink in the recesses of the plate. The press then uses high pressure to force the paper into the recesses which pull out the ink and leave a surface that can be felt with the hand in the areas which contain printed image. One type of letterpress in common use was created by the German company Heidelberg and, due to the pinwheeling arms that both loaded and unloaded the paper stock from the press, was often called a "windmill" press. Ref: Pocket Pal "A graphic arts production handbook" from International Paper 15th edition

StencilEdit

Stencil printing is a method in which ink is forced through a surface with positive spaces (solid material) and negative spaces (openings) which form the image. A simple example would be using a cardboard mask to spray-paint words on a crate or box.

Screenprinting, a form of stencil printing, is the most versatile method of printing. It uses a squeegee to force ink through a fabric screen with the non-printing areas masked with a resist or film. It is often employed to print on shirts, sportswear and wallpaper,but other uses range from glass bottles to metal plates to printing on flexible plastics and complex shapes. Screenprinting can be used to print the resists that form the circuits (traces) of electronic circuit boards. This resist keeps the metal that is meant to carry current from being etched away by the acid bath that removes the unwanted metal from the surface of the board.

ElectrostaticEdit

Electrostatic printing is used by machines such as laser printers.

InkjetEdit

The two types of inkjet are CIJ (Continuous InkJet) and DOD (Drop On Demand).

CIJ prints with a series of ink drops. Since the ink is continuous, a switch is used to either drop a dot or deflect the drop back into the ink reservoir. This is the method used to print address labels.

DOD sprays ink when it receives a signal.

Imposition is pagination on a large sheet press. This large sheet is then cut and bound. This is the process used to print books.

Table of ContentsEdit