GLOSSARY

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R

radiant energy

Energy transmitted in wave motion, that is, the electromagnetic spectrum including visible light, ultraviolet, infrared, heat and others.

rag paper

European paper was originally made from rags.

The earlier papermaking fibres came from linen and hemp rags; and later cotton was introduced. Rag papers are generally much more durable than those made from wood pulp. Rag paper implies quality paper. Modern rag papers are made most often from cotton linters: the short cotton fibres which remain after the longer fibres have been removed for the textile industry. Cotton is a good-quality fibre, but cotton linters is not the top quality.

raking light

Light from a light source which is placed at an angle to the object during its examination, in order to emphasise the surface characteristics of the object. This strongly angled light will throw up shadows where uneven surfaces appear, making it easier to see creases, lifting paint layers or other damage to a smooth surface.

reaction

In a disaster, the action taken on notification of a threat, including initial response procedures and prior to the recovery stage. Reaction to disasters should be based on sound planning. For the use of this term in its chemical sense, see Chemical reaction. See also Counter-disaster plan; Initial response procedures; Recovery.

rebate

The L-shaped groove on the inside edge of a picture-frame into which the picture, glazing, mount and backing board fit. Also spelt 'rabbet'.

reconstruction

The actions taken to recreate, in whole or in part, objects or other cultural material.

recovery

In a disaster, the action taken to salvage the collection. Recovery includes the sorting, documenting, drying, cleaning, rehousing, repairing and relabelling of items damaged in a disaster. See also Counter-disaster plan; Initial response procedures.

recovery coordinator

A person who coordinates the recovery phase, that is, trains and supervises the recovery team/s and the work flow.

recovery plan

A plan drawn up when a disaster happens to document the order for recovering damaged items and their proposed treatment. This plan is needed before the recovery phase can start. Unlike a counter-disaster plan, it cannot be prepared ahead of time because it will vary depending on the situation.

recovery specialist

A person or organisation with expertise in some aspect of the recovery phase. This expertise may be in cleaning electrical equipment and office/storage areas, or in the treatment and restoration of specific items like paintings, books or furniture.

red rot

A type of deterioration of leather, which generally takes two forms: 1) a hardening of the leather, causing it to become brittle (commonly found in leathers up to about 1830); and 2) a powdering of the leather, which can be so severe as to destroy it completely. This latter deterioration appears to affect virtually all leathers, and is apparently influenced by several factors, including (possibly) the tanning agent or agents used, ultraviolet light, atmospheric conditions (sulphur dioxide pollution) and how frequently or infrequently the book is handled.

reducing agents

Substances which remove oxygen from, or add hydrogen to, other substances. For example, photographic developers are reducing agents: they supply electrons to a system.

reduction, reduced

A chemical reaction in which one substance is changed to another by the removal of oxygen, or the addition of hydrogen to it. The term is also used generally to include any reaction in which an atom gains electrons.

Reemay

A spun-bonded polyester which is resistant to adhesives. Reemay looks like Vilene-which is used in dressmaking-and is used in paper conservation as a release material for paper and paste repair and as a support when washing fragile papers-this is a trademark/brand name.

register

a) The book, file, computer database or similar system where objects in a collection are recorded.

b) The basic record or documentation of objects.

c) The process of entering an object into the recording systems of a museum, also called registration.

registration

The process of entering an object into the recording systems of a museum by assigning a unique number, physically numbering the object, recording that number in a register and noting brief details of the object and its acquisition.

rehousing

Replacing the storage container in which an item has been housed, for example, replacing a box.

relative humidity

The amount of water vapour contained in the air at a particular temperature compared with the total amount of water vapour the air can contain at that temperature. Relative humidity-RH-is expressed as a percentage. Various materials respond differently over a range of humidity levels and there is an optimum level of relative humidity suitable for the display and storage of specific materials. The suggested RH for a mixed collection would be in the range of 45-55%.

release paper

A thin, translucent paper coated with a substance such as a silicon preparation on one or both sides to render the surface slippery and resistant to sticking. It will withstand the application of heat without sticking or otherwise damaging the work.

Renaissance wax

See Microcrystalline wax.

replica

A copy, facsimile or reproduction of an item, ideally-particularly in art collections-made by the maker of the original or under their direction.

respirator

A device worn over the mouth, or nose and mouth, to prevent the inhalation of noxious substances.

restoration

The actions taken to modify the existing material and structure of an object to represent a known earlier state. See also Conservation; Preservation.

reversibility

Ability to undo a process or treatment with no, or minimal, damage to the object. Reversibility is an important goal of conservation treatments, but it must be balanced against other treatment goals or options. Full and total reversibility is an ideal which in reality is almost impossible to achieve.

Ribloc

A ribbed, lightweight material used for making rollers on which to store unstretched paintings or large textiles-this is a trademark/brand name.

rodenticides

See Pesticide.

rollover edge

In picture framing, the edge of the canvas which is 'rolled over' the auxiliary support. See also Tacking edge.

rust

Corrosion products-iron oxides-which form on the surface of degraded iron and iron alloys. Rust is not protective, and will accelerate the corrosion of the metal until there is no iron left. See also Corrosion.