How Paper is Made Glossary of Terms

Barker
Debarking drums tumble and rub logs against each other to remove bark.

Bleaching
Pulp to be used for printing paper undergoes a series of bleaching steps. 

Blow Tank
The fibers are separated, becoming pulp, in the blow tank. 

Calendars
The paper is then run through polished steel rolls that make it even smoother and more compact. While most calenders add gloss, some calenders are used to create a dull or matte finish. 

Chemical Recovery and Regeneration 
The process in which the inorganic chemicals used in pulping are recovered and regenerated for use. 

Chipper 
The chipper reduces the logs to approximately one-inch square chips. 

Cleaners 
Clean stock is removed from the top and stock containing dense contaminates is removed from the bottom. Centrifugal force causes the dense materials to lose their momentum on the inside walls of the cleaners. This allows the dense material to settle much more quickly than the fibers. 

Dandy Roll 
Levels the fibers to make the sheet more uniform. 

Digester 
Chips in a chemical solution are cooked under pressure, dissolving and separating the wood fibers from the lignin, a natural "glue" that holds the wood fibers together. 

Dryers
The longest part of the paper machine. Steam-heated cylinders contact both sides of the paper, evaporating the water to a 5% content level. 

Felts 
Fabrics that support the mat or sheet of paper as it travels through the press and dryer sections. Press felts absorb water from the sheet as the press cylinders squeeze water out. Dryer felts hold the paper tightly to the dryer cylinders. 

Forming Fabric
Endless plastic or wire mesh screen that supports the fibers as water is removed. The fibers interlace and bond, forming a mat. 

Head Box
"Furnish" is spread out the width of the forming fabric. Furnish consists of 0.5% refined pulp, 99.5% water and trace chemicals to help bond, brighten and if needed color the paper. 

Presses
The paper still consists of 50% water when it leaves the forming section of the machine and enters the press section. There, a series of heavy rotating cylinders press the water from the paper, further compacting it and reducing its water content to 30%. 

Reel 
The paper is wound onto a parent reel and taken off the machine. 

Refine
The fibers of the bleached pulp are cut and brushed. This improves their bonding properties and strength. 

Screen 
A screen is used to separate larger chips. 

Size Press
The paper passes through a sizing liquid to make it less porous and to help printing inks remain on the surface instead of penetrating the paper. Then the paper goes through additional dryers that evaporate the liquid in the sizing and coating. 

Washing
Used to filter out any remaining lignin, chemicals and impurities. At this stage, the pulp is naturally brown and can be used to make grocery bags and boxes. 

Wet End
First section of the paper machine where the majority of water is removed from the paper. The final section of paper machine where the paper is dried is called the dry end.