Offset Paper / Woodfree Offset Printing Paper Producers / Manufacturers

WHAT IS AN OFFSET PAPER?

Offset paper or offset printing paper is a type of woodfree paper, comparable to book paper, that is primarily used in offset lithography for printing books, magazines, manuals, catalogs, posters, calendars, flyers, letterheads, publication interior sheets, brochures, and envelopes. Offset printing paper is used in both sheet-fed and web-fed printing presses.

In addition to an ISO brightness of more than 80% and grammage in the range of 40-300 gsm, offset paper has a higher amount of amount of sizing to withstand excessive moisture saturation when it is processed in the offset press dampening systems. Offset paper has strong internal bonding and good dimensional stability, higher resistance to curl, high surface strength, and a low linting level. Offset papers are available in coated and uncoated varieties and in smooth, vellum and pattern finishes.

In the coated varieties of offset paper, a layer of coating is applied to the paper. This is done to improve the paper’s durability, along with improving its brightness. This type of offset paper is often used for printing book covers, brochures, and calendars. Printing on coated offset paper is more challenging than printing on the uncoated stock due to ink smearing and slower drying. Coated stocks do not absorb ink quite easily as uncoated stocks and require inks with greater adhesion.

The uncoated variety of offset paper has a relatively coarse surface that enhances its ability to absorb printing inks and dampening solutions making it ideal for offset printing. The surface characteristics of offset paper make it easier to write on it with ballpoint and fountain ink pens and to get a clear print on it with a stamp. Offset papers are commonly used for office stationery for this reason. For printing purposes, it is possible to print high quality, multicolored graphics and illustrations and texts on these papers for a variety of products and publications. Offset papers, nevertheless, are not quite in the same league as art print papers for reproducing high-end color images.

OFFSET PAPER MANUFACTURING

Offset paper is manufactured from wood pulp mainly sourced from softwood trees like fir, pine, and spruce and hardwood trees like birch, maple, and poplar. In both cases, the wood pulp undergoes chemical processing to eliminate lignin from the pulp fibers. Lignin, a natural substance that occurs in wood, is removed to prevent the processed paper from yellowing when it is exposed to sunlight.

The softwood and hardwood pulp are often furnished together to create a smoother offset paper with a high surface strength. The softwood pulp which has longer fibers provides strength properties due to better interlocking of the fibers. The hardwood pulp has shorter fibers that provide the paper with bulk and better surface smoothness.

Offset Paper Primer