Paper is a layer of intertwined fibers formed into a sheet. This simple definition covers a seemingly infinite variety of paper available to the printer.
Paper can be separated into four general groups. There are papers that straddle one or more of these outlines.
Made primarily for the commercial offset or letterpress printing industry manufactured with a focus on efficient handling, production, and cost efficiency. Standard sheet sizes and precise sheet caliper thickness, trimmed edges, lack of watermarks that take up useful sheet area are standard. These are papers most often converted into envelopes, folders and other practical forms intended for exposure to handling and other environmental stress. Most commonly machinemade. These papers are offered often in a variety of parent sheet sizes and often on rolls (webs).
Examples: Crane Lettra, Mohawk Superfine, French Smart White
Fine Art Papers
Papers made with a primary end use of fine art techniques, having a strong focus on archival fibers content and the specific physical demands of those fine art techniques rather than considerations for offset or letterpress printing. Low cost is often sacrificed in favor of archival fibers and sizing materials for specifically desired behaviors (such as retaining moisture, allowing fiber stretch, facilitating pigment retention, maintaining neutral pH levels). The papers are primarily intended for carefully protected display as the end use and not handling or other environmental stress. Fine art papers are commonly mouldmade, and occasionally machinemade.
Examples: Magnani Pescia, Rives BFK, Stonehenge, Hahnemühle Copperplate
Papers made with the appearance as the sole focus. Fiber content and handling is secondary to appearance; often materials can be surprisingly delicate and sensitive to variables such as humidity, temperature or strong sunlight. While these papers should not be ruled out offhand, they often need careful experimentation to discover how suitable they may be as the manufacturer often does not have printing in mind and cannot provide technical information. These papers are primarily intended to look good for a short period of time and often suffer from handling or exposure to environmental stresses.
Examples: Thai Unryu, Daphne Lightweight, Shinzen, Elle Erre Carte, Nepal
Papers made by use of a hand pulled mould and deckle from a vat of fibers suspended in water. Handmade papers by nature have variation in sheet thickness, fiber distribution and sheet edge.
These variations are natural to the handmade process and often seen as desirable qualities rather than manufacturing defects. These inherent characteristics can lend significant aesthetic appeal when used properly. They may also present difficulties during printing and almost always require hand feeding and adaptation of registration methods.
Examples: Twinrocker, Margaux Estampe
Choosing from the seemingly limitless number of papers available to the new printer can be a daunting exercise. Successful presswork depends on choosing paper that will meet the job requirements best and with the greatest efficiency.
Collecting samples of available papers and educating yourself on the types of paper available is the first step in being able to choose paper quickly and successfully. Nearly all paper manufactures are happy to provide samples, often for free, and building a small collection of paper sample books can be very helpful when designing a project. Technical information on the construction and intended uses is also often provided by paper mills and paper vendors on their websites or and is often included with samples.
Paper Selection Considerations
Once the general design process and aesthetic requirements of a project have been established paper selection is a process of elimination that can be broken down into simple factors.
Does the paper meet the practical requirements of the letterpress to be used for the project?
The paper needs to feed through the press, provide a consistent printing surface, and receive ink readily. Presses that are hand fed offer more alternatives for sheet handling than those that are automatically fed. Also, cylinder presses require the ability of the intended paper to adhere to the curve of the cylinder during printing while a platen press can receive paper which has little ability to flex. A paper with a pronounced deckle would present feeding and registration issues as the sheet edge is inconsistently defined. A paper with inclusions such as bark or other plant materials alter the compressibility of the sheet and could damage type or plates.
Can the paper provide the surface and physical needs of the project?
Will the paper need to be thick and soft to allow for deep impression? Will it need to be smooth to reproduce details in small/fine typefaces? What paper finishing steps, such as scoring, folding, and cutting, are planned? Is the paper available in the sheet sizes and grain orientations needed for printing your form? This will further eliminate a large number of papers and begin to narrow the options. Physical samples are the best tool here, technical information from the paper manufacturer on the intended uses is also helpful.
Is the cost of the paper practical for the project’s budget?
Determine the best number of press ready sheets to be gotten out of the parent sheet. Is there a similar paper available that may yield more press sheets?
Using the above factors, a small group of aesthetically and practically applicable papers to choose from can be gathered from samples and presented to the client for selection or be deliberated over by the printer. Keeping detailed notes on the pros and cons of various paper types, their behavior on press, and samples from print work can also add to your paper knowledge library and expedite future selections.
Paper Care & Storage
Paper should be stored flat for any length of time in a well ventilated, average humidity environment, carefully wrapped in an acid free kraft paper. Wrapping paper with a high acid content coming in direct contact with paper can discolor acid free paper if left for longer periods of time. Buffering agents in the paper may mitigate this to some extent but it’s best to provide acid free interleaving if acid free wrapping cannot be obtained.
After any conversion work, unless put into immediate use, press sheets should be again wrapped and brought into the pressroom and unwrapped only when presswork is about to begin. Limit handling as much as possible, and then only with clean hands. Always grip the paper with two hands at opposite corners and allow the paper to flex in a smooth curve to prevent kinking or darting.
Ideally paper will be allowed to acclimate to the pressroom for 24 hours prior to presswork as abrupt changes in humidity and temperature without a period of acclimation may cause paper to expand, contract, or stretch on press causing high tolerance registration difficulties.
Finished works should be carefully dried, stacked, and wrapped as soon as possible and stored flat in an area of average humidity and temperature.
acid free Paper with neutral pH of 7 is considered acid free. This may be naturally occurring in the fiber (such as cotton) or established artificially during sheet manufacture by adding alkali buffering agents such as magnesium or calcium carbonate. Acidity has a negative effect on paper longevity. Paper that is not acid free may yellow and become brittle over time, depending on environmental exposure.
brightness How much light the paper sheet reflects.
calendered Accepted as a general term for smooth. Literal description: the final pass of the newly formed paper through the calender or series of rollers to determine its final finish. A calendered finish may range from an even finish to exceptionally smooth. Super calendered paper has been run through an additional calender and has a smooth glossy finish.
caliper The thickness of a paper sheet as measured in 1/1000 inch increments or “points.” 1/1000 inch = 1 pt. A common thickness measurement in commercial paper and allows for efficient press makeready, as packing may be easily adapted to sheet thickness.
coated paper Paper with an applied coating which varies depending on intended application. Coated paper usually prevents ink penetration and may require careful handling and drying techniques.
deckle The uneven, often feathered unfinished edges of a sheet, uncommon on machine made paper. Also refers to the part of the tool combination used to form sheets in the fiber vat when hand making paper.
fiber The material used to form paper sheets. Cotton, cellulose, gampi, hemp and other fibers are used in papermaking. The two most common are cellulose (from breaking down wood pulp) and cotton.
finish The surface of the paper sheet. Mills use several different terms to describe the finish of their papers: vellum, fine textured, smooth. Samples may be required to determine the exact meaning.
grain The average orientation of fibers in the paper structure. Paper will tear and fold more easily parallel to the grain direction. If the fibers of a sheet run parallel to the longest edge the sheet is said to be grain long, if along the short edge, grain short. Grain in a parent sheet is important to note as grain direction may affect printing, grain should run across the cylinder of a press, if possible, to limit stretch and allow the sheet to easily bend, and any scoring should run parallel also.
handmade Paper formed with a mold and deckle from a vat of fibers suspended in water. Often the sheet will have four deckled edges.
machinemade Paper formed on a Fourdrinier Machine, all edges are finished with no deckle. This is the dominant method of commercial paper production due to economy and scalability.
mouldmade Paper formed on a cylinder mold paper machine, this is commonly how fine art papers are made. Deckles will run on only two edges of the sheet.
parent sheet This refers to the paper sheet size as offered by the manufacturer.
press sheet This is the paper size as run through the press, cut down or ‘gotten out’ from the parent sheet size. After the press run, the sheet may be further trimmed.
sizing Material added to the paper to control ink absorbency and stiffness. If added into the fiber prior to sheet formation it is referred to as ‘internal sizing’. If added after sheet formation by passing through a tub of size or spraying, it is called ‘tub sizing’ or ‘surface sizing’ respectively. Paper without any form of sizing is referred to as ‘waterleaf’.
uncoated paper Paper of entirely consistent material content throughout with no added materials to the surface, usually ink receptive.
watermark A specific mark made during manufacture to indicate what mill made the paper. Fine art papers often include coded information which may be cross referenced by the mill to determine the exact date of manufacture. True watermarks can only be formed on mouldmade or handmade sheets as they are made using a raised wire or metal shape to displace fibers during sheet formation. This allows light to pass more easily through the less dense area, forming an image or characters if backlit.
weight Commercial papers are commonly made to this measurement. Traditionally this is measured in pounds per five hundred sheets of a fixed size. Example: paper described as 90lb cover stock weighs 90lbs per 500 20 x 26 sheets. Weight may also be described by using the gram weight of a sheet, theoretically one square meter in size, noted as ‘grams/sq meter’ or ‘gsm’ which allows for equal comparison regardless of sheet size.