Baby Steps To Print Purchasing Know How
The Printing Crash Course - Printing School
Paper Stock Considerations
The choice of paper for the piece being printed is the first item to be decided on. Often this subject is the last item that is decided by designers, or users of print and not enough weight is ever given to this important base of the printed job. Remember - the paper you choose will support your printed idea, give it enough consideration. There are many items that need to be identified when choosing the grade, finish, color, thickness and grain of the paper being used.
Opacity is the lack of transparency that allows a sheet to conceal print on its reverse side. Opacity is greatly influenced by basis weight, brightness, type of fiber and filler. In testing, reflectance of paper is measured when backed successfully by a white body and a black body. The ratio of these two measurements determines the opacity reading.
Aside from its aesthetic importance, paper brightness affects the legibility and contrast of printing. The brightness test measures the reflectance of paper under strict optical conditions and relates it to a white standard (Magnesium Oxide). This test is mainly applicable to white paper grades.
Finish is a complex paper property related to its smoothness. Paper can be used as it comes off the driers of a paper machine, or it can be machine calendered and later supercalendered. Uncalenered, machine calendered and supercalendered papers vary greatly in smoothness. The usual finishes of uncoated book papers are, in order of increasing smoothness: antique, eggshell, vellum, smooth and luster. These finishes are classes together because all can be produced in the machine. Additional smoothness is obtained with supercalendering. Coating, of course, further improves the finish and smoothness. Some finishes are embossed on the paper after it leaves the machine. These are produced by a rotary embosser, a machine similar to a mangle, with the paper passing through it dry and under pressure. Commonly used embossing patterns are linen, tweed, and pebble.
The smoothness is a measure of paper surface irregularities. The property affects many end uses, particularly the appearance of printing. The test is conducted by clamping the paper against a flat surface and measuring rate of air flow passing between the two surfaces. The Sheffield instrument is most commonly used, a higher number indicating a rougher sheet. Some typical smoothness values are: 10 -30 for very smooth paper; 100 -150 for smooth paper and 200 -250 for vellum paper.
Grain Direction: Long and Short Paper Grain
The direction in which most fibers of a sheet of paper lie is called the grain direction. As paper is formed, the slurry of fibers moves forward on the paper machine at high speeds, aligning the fibers in the direction of the movement and creating the grain. At the same time, the machine shakes the slurry of fibers from side to side, so that the fibers crisscross. This crisscrossing creates a web of fibers, and gives the paper strength in both directions, while maintaining a predominant grain direction.
How Grain Affects Strength
Making a tear in a sheet of paper along the grain is easier than tearing a sheet across the grain. Tearing with the grain pulls fibers apart from each other, while tearing across the grain tugs at whole fibers, which have greater inherent bonding. Folding with the grain is also easier than folding across the grain. Folding against the grain may cause the paper to crack or buckle if it has not been scored first. Generally, lightweight paper does not need to be scored. It is usually best to score 100# text and all cover weight. Recycled paper is less apt to crack when folded against the grain, because the fibers are shorter and the bond not as strong.
The most expensive portion of any printed job you will undertake will be paper. Use all resources to identify and seek the proper paper for the application.
Mostly brochures, flyers, sell sheets, inserts and leaflets are printed on coated stocks varying in thickness from 80lb. to 100lb commonly known as "Text Weights".
Business cards and Post Cards are printed on 10 or 12 point coated cards commonly known as "Cover Weights".
To achieve cheap printing prices, use the most common weights of stocks available. The most common grades are sold in much larger scales, and in the economy of scale, the price of the paper is relatively cheap.
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