Glossary / R

Rag paper
Today rag paper is mostly made from vegetable fibres consisting of cellulose, such as cotton, linen, hemp and ramie. Rags are the most precious raw material for the papermaker. Rag papers and rag–containing papers with admixtures of chemical pulp are used for banknotes, deeds, documents, books of account, maps and copperplate engravings and as elegant writing papers. They are also used for special technical applications.

Rag pulp
Raw material for the making of paper obtained by pulping rags made from plant fibres (cotton, linen, hemp).

Ream
Term used for a pack of paper made up of a certain number of sheets (usually 500) of the same format and grammage. Depending upon the format and weight of the paper the pack may be subdivided (250, 125, 100, 50 sheets).

Recovered paper
Paper recovered for recycling into new paper products. Recovered paper can be collected from industrial sources (scraps, transport packaging, unsold newspapers...) or from household collections (old newspapers and magazines, household packagings).

Recovered Paper Base
Solid, compressed stack of recovered paper, sorted by grades, intended to be recycled by some papermills, to produce paper and board.

Recovered Paper Grades
Recovered paper sorted by types in order to be recycled by paper mills. Specific grades are used by paper mills, in order to produce different types of paper and boards.

Recovery boiler
Boiler used to burn black liquor from chemical pulping for recovery of inorganic chemicals as well as for energy production.

Recovery rate
Volume of paper recovered as a percentage of volume of paper consumed.

Recycled fibre
Fibre obtained from recovered paper; also secondary fibre (cf. virgin fibre).

Recycled fibre pulp
Pulp produced from recovered paper to be used in papermaking.

Recycling
Use of recovered waste paper and board by paper mills to produce paper and boards.

Refiner
A machine containing rotating disks between which wood chips are broken down into fibres for pulp making.

Refiner mechanical pulp (RMP)
Mechanical pulp produced by passing wood chips between the plates of a refiner.

Refiner sawdust pulp
Mechanical pulp produced from sawmill dust.

Reflectivity
Ability of paper or board to reflect light; a measure of gloss.

Reinforcement
Method for strengthening paper with an insert or surface layer of glass or other synthetic fibre or metal.

Reinforcement pulp
Softwood chemical pulp added to give paper greater strength and to improve runnability on the paper machine or printing press.

Reject
Material removed and discarded during the cleaning of pulp/stock.

Relative density
Mass of a unit volume of a particular substance.

Release paper
Release paper is used to prevent the sticking of glue, paste or other adhesive substances. Coating paper with silicone yields papers with a surface that prevents adhesion of most substances. Application: cover material for self–adhesive papers or films, e.g. in label production.

Retention
Proportion of fibre and filler retained on the paper machine wire.

Roofing paper
Board that is impregnated with tar, bitumen and/or natural asphalt.

Rotogravure printing
Direct printing process based on engraved wells. The engraved form is inked and then a blade (doctor) scrapes the excess ink off the surface of the cylinder before it comes into contact with the sheet to be printed. Guarantees high quality reproduction on a wide range of materials but given the high cost of engraving the printing element it is only viable for long print runs.

Runnability
How smoothly paper runs through a paper machine or printing press (also how well cartons run on an automatic packaging line).