Paper stocks are classified as groundwood when more than 10% of their pulp is produced from a mechanical process that grinds wood into pulp. They are great for non-permanent printed items such as newspapers because they tend to yellow quickly and become brittle. They have low tear strength (very short fibers) are less bright and less permanent than paper produced from chemical pulp.
Paper stocks are classified as freesheet when they are free of pulp produced from a mechanical grinding process. Chemicals, rather than grinding, are used to reduce the pulp to fibers. The result is higher tear strength (longer, stronger, and cleaner fibers) and paper stock that is brighter and much more permanent than groundwood stocks.
Coated stocks receive a surface coating to create sharper detail and improved color density. Adding a coated clay pigment improves the smoothness and reduces the absorbency. Common coated finishes are matte, dull, cast, gloss, and high gloss. Cast coated is an exceptionally glossy finish (usually on one side only) produced with a coating that is allowed to harden while in contact with a highly polished chrome surface. Uncoated stock has no coated pigment applied. Common uncoated finishes are vellum, antique, wove, or smooth.
The grain of the paper refers to the direction of the fibers in a sheet of paper. Opacity measures (percent) the amount of light passing through a sheet of paper. Papers containing more fibers and/or fillers (more opaque) have the ability to hold a printed image without showing through to the backside. Thicker paper does not guarantee more opaqueness.
Finish refers to the surface characteristics of paper stock, such as luster, or texture which differs from grade to grade. Different finishes have varying degrees of printability, smoothness, and ink receptivity. The surface structure has the ability to create interesting visual and tactile qualities. Is the paper smooth like glossy cover or rough like antique finish? Does the paper have a glossy appearance like coated glossy or is it dull like bond. Does the paper have a high ink absorption rate like vellum or poor absorption like coated? Note that the finish of paper has nothing to do with the weight.
Finishes are achieved through a variety of manufacturing methods. Finishes such as linen, tweed, and pebble are created with an embossing roller, which presses relief patterns into the paper when it comes off the paper making machine. Felt finishes are produced on the paper machine by pressing the newly made paper against various felt patterns. Finishes such as antique, eggshell, vellum, smooth, and luster are created during the paper making process by passing the paper through a series of “calendaring rollers,” which are vertical, cast-steel rollers with polished ground surfaces.
Some of the more common and classic paper finishes:
- Bond – Relatively high-grade paper stock generally used for letters, business forms, and copying.
- Cockle – Simulates characteristics of hand made paper with a wavy, rippled and puckered finish. The effect is created by air drying the paper under minimum tension.
- Felt – Soft texture on uncoated paper created with a felt covered roller or felt patterned rubber roller during the paper making process. Can also be accomplished as an offline process and does not affect paper strength.
- Gloss – Produces a shiny and reflective surface on coated papers by adding compounds during the paper making process. Higher quality coated papers lend themselves to higher gloss.
- Laid – Has the appearance of fine lines running the length of the paper horizontally and vertically. Produced with a special roller that creates the pattern in the wet paper during the paper making process.
- Linen – Resembles linen cloth and is usually produced as an offline embossing process after the paper making process.
- Matte – Produces a smooth but dull appearance.
- Metallic – A coating that simulates the color and gloss of metal with a thin film of plastic or a thin film containing metal.
- Parchment – An old or antique appearance which is very durable and grease resistant. The finish is the result of washing sulfuric acid over the paper, to melt the outer paper fibers which fill the voids in the paper, and then quickly neutralizing the acid wash.
- Smooth – A very smooth and level finish which results from paper passing through sets of rollers during the paper making process; known as calendering.
- Vellum – Has an eggshell appearance, a high ink absorbency rate, and is one of the most popular uncoated finishes. Appears smooth to the untrained eye, although has a subtle roughness (tooth) which separates it from smooth.
- Wove – A slight texture (standard smooth even finish) made by a felt roller covered in woven wire on uncoated paper. One of the most common papers used for general printing.
Bond, smooth, wove, and vellum are reasonably smooth to the touch with subtle differences. Felt, laid, and linen are textured visually and to the touch. Cockle and parchment have an antique appearance with a company logo and a small amount of supporting text.
When it comes to custom pocket folders, most people opt for coated, linen, vellum, felt, or smooth.
Image Credit: Yaronimus Maximus