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THE PAPER MANUFACTURING PROCESS

(21/11/2015)

Whether fiber is pulped from trees in a pulp mill, deinked from recycled paper in a deinking mill, or pulped from agricultural fibers, it all meets in the headbox at the beginning of the paper machine, where the proper mix of fibers is achieved before it is made into paper. 

 

 

Whether fiber is pulped from trees in a pulp mill, deinked from recycled paper in a deinking mill, or pulped from agricultural fibers, it all meets in the headbox at the beginning of the paper machine, where the proper mix of fibers is achieved before it is made into paper. The pulp runs out of the headbox as a slurry (a mix of fibers with approximately 97% water) onto the wire (a mesh screen that runs continuously above a trough). Much of the water drains out as the fiber catches onto the screen, but small fibers may also fall into the trough, to be returned to the headbox or washed away as effluent. As the fiber crosses the wire, it begins to take a wet, sheet-like form. Any waste at this point is called wet broke.

Next, the newly-forming paper goes through a series of dryers, beginning to look more like the paper familiar to buyers. At the end, it rolls onto a long reel, called a log (which weighs 3 to 5 tons). Waste from the dryers up to this point is called dry broke. It is cheaper to reuse mill broke than to use or buy new wood pulp, so it is always in the economic interest of a paper mill to reuse this material. Virtually 100% of mill broke is recycled back into new paper.

Traditionally, any scraps in the mill were called "mill broke." This is still the designation in Europe and other countries. But in the United States, the paper industry negotiated with the EPA to categorize only scraps up until the end of this initial papermaking process as mill broke, so that they could count subsequent scraps as recycled or recovered paper. Therefore, EPA's "recovered paper" category starts in the mill as the log is cut into smaller rolls, appropriate for printers' web-rolls or for converting into products such as sheets or envelopes.

After leaving the paper mill, paper is sent to a converter to be made into paper products. Sometimes the converter is in another part of the paper mill itself. The converter cuts the rolls of paper into products such as sheets, envelope forms, and computer paper. Waste created by the converter is sent directly back to the mill. This clean waste material, called pulp substitutes, is a direct substitute for wood pulp and requires no additional processing. It is also less expensive than virgin pulp and nearly all is recycled back into new paper.

After leaving the converter, some paper is sent to printers and some to end-users. The scrap created by printers is called deinking waste since it needs to be deinked to remove inks, glues and waxes added during the printing process before it can be recycled.

Up until paper leaves the printer for the end-user, all of the categories of scrap paper - broke, pulp substitutes and printers' deinking wastes - are called preconsumer material. The EPA, as well as many states and environmental labeling programs (including the Federal Trade Commission's guidelines), do not allow wet broke to count as recycled material. Material collected from the point of dry broke on is generally accepted as recovered fiber, appropriate to count as recycled content.

From the printer, paper goes to the end-user (the consumer). The scrap that comes back from end-users through curbside and office collection programs is called postconsumer fiber.

 

 

RECYCLED FIBER SOURCES

 

 

Not Counted As Recycled Content

RECOVERED MATERIALS

Fiber Type

Forest Residues

Mill Broke (Wet, Dry)

Pre-consumer

Mill Converting Scraps

Pre-
consumer

Pulp Substitutes

Pre-
consumer

Deinking Fiber

POST-
CONSUMER

Source

FOREST, SAWMILL:Cutting Trees, Milling Timber

MILL: Production

MILL: After completion of Paper Manufacturing Process, excluding Mill Broke (e.g. sheeting from rolls)

CONVER-
TERS: 
Value-added production, e.g. making envelopes, continuous feed paper, sheeting from rolls

CONVER-
TERS, PRINTERS:
Value-added production using inks and other additives

CONSUMERS: Homes, Businesses

 

 

 

THE FINISHED PRODUCT


Quality

Many recycled papers sold in the early 1980s were still in a development phase and it sometimes showed. Printers complained about linting, dusting, picking, limpness and many other problems. Customers complained about jamming and splotches. Now recycled papers are made by the best paper mills in the world and many high quality recycled grades are on the market. Recycled papers perform competitively with virgin sheets in printing presses, copiers, laser printers, computers, inserters, and most other paper equipment.

The only differences now are aesthetics, and these are very minor. Sometimes recycled paper has slightly more small specks in the paper than virgin sheets. And recycled papers may be a point or two lower in brightness than their virgin paper counterparts. (Brightness is measured by the percentage of light reflected back from the paper.) But this difference would not be discernible unless the two sheets were held up next to each other.

Consumers are beginning to realize that high paper brightness may not be the best value - usually it is achieved by bleaching with chlorine, which is toxic - and that high brightness may actually undermine the readability of material printed on the paper.

Recycled and tree-free papers generally have higher opacity (which means they are harder to see through), often considered an asset, especially for double-sided printing. Publishers, for example, can save on paper by using a thinner, less expensive sheet if it has more opacity. Using a thinner sheet can also save on mailing costs.

Paper users have found that environmentally sound papers work well in a variety of situations. For example, a survey of commercial printers using recycled paper, conducted by Paper Sales magazine a few years ago, found 80% of them reporting that, even then, recycled paper worked as well as, or better than, virgin paper.

PRICING

Recycled commodity paper - copier, offset, and other office papers - costs, on average, 7-10% more than comparable virgin papers. Although making recycled paper should technically be no more expensive than making virgin, in fact its cost is often higher due to a combination of factors. On the production side, economies of scale are more favorable to commodity virgin paper. Far more virgin paper is produced, and on much larger paper machines than most recycled paper. Virgin paper mills that convert to recycled must incorporate the costs of retrofitting. And many recycled sheets are made from pulp bought on the open market, which is more expensive than paper made from pulp in a facility integrated with the paper machine. In addition, paper marketers know that buyers are used to higher prices for recycled paper and therefore may not price it as competitively as possible.

Specialty papers, however, such as designer papers (text and cover) and rag bond papers, are essentially equal in price because both recycled and virgin papers are made on the same kind of papermaking machines. In fact, the recycled is now often less expensive than virgin paper.

Paper prices in the early 1990s were at the bottom of the industry's pricing cycle, so paper buyers' budgets were battered by the huge run-up in all paper prices in 1994 and 1995. Many purchasers pulled back from buying recycled paper during the higher pricing, explaining that although virgin paper prices were high, too, they couldn't justify spending even more for recycled. This was bad news for paper and pulp mills which had just invested in new deinking and recycled paper systems. Some of them stopped producing recycled paper, in response to high scrap paper prices and reduced consumer demand. This is why it is crucial that paper buyers keep sending a consistent message to the paper industry, through their purchases, that recycled paper investments are worth the risk.

Tree-free paper prices are often at the high end of recycled paper prices or higher, although their prices are coming down as more are sold and some buyers join in purchasing large lots. Some processed chlorine-free papers are competitively priced. Tree-free papers face an uneven playing field because of government timber subsidies as well as a totally out-of-balance economy of scale. As they become more widely produced in the U.S., their prices will become more competitive. Even now, buyers frequently can keep prices in line by substituting a lighter grade (because many have higher opacity) and some find that this actually saves them money over what they would have paid for more traditional choices.

For all higher priced, environmentally sound papers, using innovative waste prevention concepts can keep paper budgets down even when the individual paper purchases may cost somewhat more.