Glossary / C

Calcium carbonate
Used in papermaking as a filler or coating pigment..

Calendered paper
Paper that has been calendered in order to obtain a smoother, more glossy surface than originally.

Calendering
Mechanical treatment applied to paper to make it smoother and glossy. The smoothness is achieved by means of pressure, whilst the gloss is achieved by friction. As a result of the compression, calendering always reduces the thickness, the porosity, the compressibility, the opacity and the whiteness of the paper. These side effects are often undesired in the case of printing papers. Calendaring, on the other hand, has a little impact on the strength of the paper.

Caliper
Thickness of paper, usually measured in nanometers.

Capacitor paper
See "Electrical insulating paper".

Capacity utilisation rate
Indicates the efficiency (%) at which a mill or machine is operating.

Carbon dioxide (CO²) 
Produced by burning coal and other carbon containing products. Burning fossil fuels or wood based products raises atmospheric carbon dioxide levels.

Carbon paper
Carbon paper is a thin paper with a waxy coating, that is used to produce carbon copies on typewriters or other office equipment. Carbon base paper is made from chemical pulp.

Carbonless copy paper 
Paper that permits making multiple copies without intervening layers of carbon paper. The paper translates pressure into a dye reaction which transfers the image to the copy. Carbonless copy papers are mainly used for continuous form sets, for covered pay slips, for vouchers to be dispatched by post and for payment forms. In the US and some other countries, carbonless copy paper is also called NCR paper (= Non Carbon Required).

Cardboard
Paper product with grammages of between 151 and 400 gsm. Cardboard may comprise a single layer or several pies, stuck together when wet or with glue. It is produced with better quality raw materials than board. There are great variety of cardboards, which differ widely in their fibre composition, surface treatments and uses.

Cast–coated paper 
Cast–coated papers are coated papers that have obtained their high gloss by moulding on a highly polished, chromium plated drying cylinder.

Causticizing 
Process by which green liquor from sulphate pulping is converted to white liquor, thus allowing the cooking chemicals to be reused.

Chemical oxygen demand (COD)
The amount of oxygen consumed in complete chemical oxidation of matter present in waste water; indicates the content of slowly degradable organic matter present.

Chemical pulp 
Carboydrate polymer of plant origin that is the main component of the fibrous parts of plants. Various grades that differ in their separation methods and in the grade of wood used as the source are available for use in the paper industry. The paper products that can be produced vary with the grade of cellulose.

Chemicals recovery
In chemical pulping, the recovery, treatment and regeneration of cooking chemicals.

Chemi–thermomechanical pulp (CTMP)
Chemi–mechanical pulp produced by treating wood chips with chemicals (usually sodium sulphite) and steam before mechanical defibration.

China clay 
Mineral (kaolin) used in papermaking as both filler and coating pigment.

Chipboard/Grey board 
Paperboard made from waste paper pulp, rough or machine glazed, also lined on one or two sides or unlined.

Chips
Fragments of wood, obtained through a grinding process, used to produce pulp.

Cigarette paper
This light weight, unsized paper (grammage 18 to 24g), converted to improve glowing. It normally has a filler content of approx. 30%.

Clarification
Separation of a solid component from a solution.

Clarifier
Basin where sludge is removed from treated effluent by settling; see Activated sludge treatment.

Coating colour kitchen 
Department where coating colour is prepared and mixed.

Combined deinking 
Deinking process combining flotation and washing; cf. flotation deinking, washing deinking.

Coated paper
Paper with one of more layers of coating (pigments and adhesives applied to one or both surfaces of the sheet during the coating process). Coatings are applied to confer particular characteristics, especially printablity. The choice of components determines the degree of smoothness, gloss, opacity, printability and colour yield of the inks.

Coating
Paste of pigments and adhesives applied to one or both sides of the sheet during the coating process. The choice of pigments used determines the smoothness, gloss, opacity, printability and chromatic yield of the printing inks.

Condensing power
Power generation in which fuel is burned for electricity production only.

Consistency
Dry solids content (%) of pulp present in a pulp slurry.

Continuous cooking
A method used in chemical pulping in which raw material is fed continuously into the digester, while at the same time pulp and black liquor are removed (cf. batch cooking).

Converting 
The operation of treating, modifying, or otherwise manipulating the finished paper and paperboard so that it can be made into end–user products.

Cooking 
A process for producing chemical pulp by treating wood with a cooking liquor at a certain temperature and pressure.

Cooking liquor 
Liquor made up of selected chemicals and used for cooking pulp.

Copying paper
Copying paper is an uncoated paper in woodfree or mechanical grades, white or coloured in A4 and A3.

Core 
The tube, usually made of paperboard, on which a paper roll is wound.

Corrugating medium
Papers used as fluting for the production of corrugated board.

Corrugated board
Corrugated board is a material mad up 2/3 layers of paper (flat sheet) that are stuck to other, fluted sheet. Such a structure offers specific strength and rigidity based on the layers that are joined together. There are three grades of corrugated: deep flutes (producing a board with a thickness in excess of 4.5 mm), medium flutes (from 5.5 to 4.4 mm) micro–flutes (with a thickness less than 2.5 mm).

Critical load
Highest pollutant load that, in the long term, does not damage essential characteristics in an ecosystem.

CTMP
See chemi–thermomechanical pulp.

CWF (Coated Woodfree)
Coated woodfree paper made from pure chemical pulp, available in various sizes or on reels.