Calcium carbonate
Used as a filler in alkaline papers, calcium carbonate is found in a variety of natural substances such as chalk, limestone, marble and oyster shells. A key ingredient in paper coatings, it enhances smoothness, brightness, opacity and ink affinity.

Calender
A stack of highly polished metal cylinders at the end of a paper machine that smoothes and shines the paper surface as sheets pass through.

Caliper
A measure of paper thickness expressed in units of a thousandth (1/1000th) of an inch (points or mils). Caliper is an important indication of a sheet's uniformity, which is important for consistency on press and in the bindery. Also known as thickness or bulk.

Camera ready
Copy or art that is ready to be imaged onto film in the platemaking process. Mechanical, velox or stat.

Casebinding
The kind of binding used for hardcover books.

Cellulose fiber
The fibrous structural support of plant cells that is processed into pulp for papermaking.

Center spread
The facing pages in the center of a bound signature.

Chain lines
The lines on laid paper parallel with the grain; also referred to as "chain marks."

Chalking
Improper drying of ink. Ink vehicle has been absorbed too rapidly into the paper leaving a dry, weak pigment layer that dusts easily.

Character
A type fonts letter, number, symbol or a blank space in typesetting.

Character count
The number of characters in a line of text, page or group of text.

Chemical ghosting
A light duplication of a printed image on the other side of the same sheet, created by chemical reaction by the ink during the drying stages; also referred to as "gas ghosting."

Chemical pulp
Wood fiber cooked using chemicals producing a pulp used to manufacture numerous printing papers and paperboard products. Papers manufactured with chemical pulp are called "free-sheet" papers.

Chemical pulping
The chemical solution used to separate wood fibers from lignin in the pulping process.

Chip board
An inexpensive and thick one-ply cardboard, typically made from recycled paper stock.

Chlorine
Chlorine and its compounds were commonly used to bleach fibers. This has been mostly eliminated. Virgin fibers are generally ECF, meaning no elemental chlorine, or TCF, meaning the bleaching is done with hydrogen peroxide, oxygen or ozone. Recycled fibers are generally PCF, meaning they were put back into the paper without the use of any chlorine or its compounds. The Environmental Protection Agency approves calling 100% post consumer fiber produced without chlorine by the term "TCF."

Chromalin proofs
A proofing process used in printing. This process utilizes photosensitized clear plastic, which is exposed to the image and processed in layers of color to simulate the final printed image.

Cibachrome
A full-color positive photographic print made from a transparency.

Clasp (envelopes)
Metal fastener sometimes used with remoistenable gum on booklet and catalog envelopes, allowing for repeated opening and closing of the envelope.

Clay
A natural substance used as both a filler and coating ingredient to improve a paper's smoothness, brightness, opacity and affinity for ink.

Clear formation (also close formation)
Describes paper fibers that are uniformly dispersed within a sheet of paper - a characteristic of quality paper.

Cloudy formation
Same as cloud effect; cloudy. Opposite of clear or close formation. Indicates unevenness and lack of uniformity of paper fiber structure.

Coated Paper
Paper that has been coated with clay and other materials to improve printability.

Coating
In platemaking, the light-sensitive polymer or mixture applied to a metal plate. In printing, an emulsion, varnish or lacquer applied over a printed surface to protect it. On paper, coating ranges from dull to very glossy. This creates paper with greater smoothness, higher opacity and better ink holdout than uncoated papers.

Cockle finish
A rough, uneven, hard paper finish. Most frequently manufactured in bond papers.

Cold color
A color on the bluish side.

Cold pressed
A paper surface with a slight texture produced by pressing the finished sheet between cold cylinders.

Collate
In binding, gathering sections (signatures) in sequence for binding.

Collotype printing
Collotype, or photogelatin, was and still is the only process that can print a full tonal range without screening. It is relatively rare - used for limited-edition art prints of exceptional quality, and is a slow process capable only of small print runs.

Color balance
The correct combination of black, cyan, magenta and yellow to (1) reproduce a photograph without color cast, (2) produce a neutral gray or (3) reproduce the colors in the original scene or object.

Color bars
Printed bars of ink colors used to monitor a print image. These bars show the amount of ink to be applied by the press, the registration and the densities across the press sheet.

Color comp
A mockup of a proposed layout used for presentations.

Color correction
Any method such as masking, dot etching, re-etching or scanning, used to improve color rendition.

Color-fastness
Colored papers that will not run when wet or fade in the presence of exposure to bright light, heat, etc. Lightfast and sunfast are variations of the term.

Color key
An overlay proof with just one color per sheet of acetate (3M Company trademark).

Color process printing
Printing performed using cyan, magenta, yellow and black inks, each requiring its own negative and plate. Also called process color or four-color process.

Color proofs
Initial printed pieces pulled off the press for final approval.

Color separation
The process of separating full-color artwork or transparencies into the four primary printing ink colors of magenta (red), cyan (blue), yellow and black by using various photographic/scanning methods. Needed to prepare plates for printing color work Today, separations are typically made using electronic laser scanners.

Color substitution
A way to alter the look of an image. One ink is substituted for another, often in four-color process printing. Keep in mind that color is substituted on the entire separation affecting every place it appears within the image.

Color transposition
Transposing color negatives (such as swapping magenta and cyan) is an easy and inexpensive way to achieve intriguing effects with conventional processes. Be sure to preview how the transposed colors will look on press by color proofing the image on the chosen paper stock beforehand.

Colorcurve^TM System
A color matching system based on light reflectance curves rather than on ink formulations. This system addresses the tendency for some colors to appear different on different surfaces, materials and under different lighting conditions.

Commercial (envelopes)
General term for the most common style of business envelopes. Open sided, with or without windows.

Commodity papers
A classification of low-quality bond and offset papers.

Composite image
Multiple picture images placed together to form a single, combined picture.

Comprehensive (comp)
A full-size mock-up of a proposed design, showing layouts of images and type, as well as use of color and paper.

Comprehensive proof
Final proof presented in the format the printed piece will take.

Conditioning
Allowing paper to adjust itself to the temperature and humidity of the printing plant prior to use.

Continuous tone
Images that have not been screened and contain gradient tones from intense black to white, such as a black and white photograph; tonal gradation without use of halftone dots.

Contrast
The tonal gradation between highlights and shadows in an image. High contrast features extreme light and dark areas.

Converter
Company that converts paper from its original form to usable products such as envelopes, label stock, announcements etc.

Copy
Any furnished material (typeset manuscript, pictures, artwork, etc.) to be used in the production of printing.

Corner card (envelopes)
Return address and other identification of the sender in the upper left corner.

Correspondence papers
Writing papers in attractive finishes, weights or colors.

Cotton content paper
Paper made with a minimum of 25%, and up to 100%, cotton fiber. Today most cotton content papers are made for letterhead applications.

Cotton linters
Cotton fibers that adhere to the cottonseed used to produce pulp for cotton fiber papers.

Coupon (envelopes)
See bang-tail.

Cover paper
Generally heavier weight, durable, stiffer paper that is ideal for the outside covers of annual reports, brochures, catalogs and booklets, as well as for business cards and folders; available in a variety of finishes and colors.

Creep
When saddle stitched binding is used for a large quantity of sheets, the more of a problem there can be with "creep." Creep occurs when inner sheets stick out further than those closer to the outside. To compensate for this, pages are "shingled" so that the inner margin, or "gutter," is increased on pages from the inside of the book to the outside. Increasing the gutter moves the printed area closer to the outside margin so that when trimmed, the printed copy appears to cover the same portion of each page.

Crop marks
Specifically placed marks attached to artwork that show the area to be printed.

Cropping
Resizing original photographs or illustrations to a different size.

Crossovers
Also known as bridge, gutter jump and gutter bleed, crossovers are images or graphics that extend across two facing pages, crossing over the gutter or binding. To check alignment, color match and back up, just fold the press sheet.

Curl
Undesirable distortion or waviness that sometimes occurs along the edges of a sheet when the paper is exposed to excess moisture, humidity or other physical stresses. This tendency is less likely in papers with recycled content because the paper fibers are shorter.

Cut-size
Writing and business papers that are cut to a finished size of 8 1/2" x 11", 8 1/2" x 14", or any other size 11" x 17" or smaller. Cut-size papers are usually packed in reams of 500 sheets and sold in office supply stores.

Cut to register
Term used for watermarked letterhead papers to indicate the watermark will be cut to appear in a predetermined position on the finished sheet. Also referred to as a localized watermark.

Cutter dust
Paper dust resulting from cutting or trimming the paper that can transfer to printing blankets causing problems during a press run.

Cyan (process blue)
One of the four process colors.