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The Oddy test is a procedure created at the
Each metal detects a different set of
Institutions that use the Oddy test in their research are mainly art museums such as The J. Paul Getty Museum, The Nelson-Atkins Museum of Art, and the
British Museum
The British Museum is a Museum, public museum dedicated to human history, art and culture located in the Bloomsbury area of London. Its permanent collection of eight million works is the largest in the world. It documents the story of human cu ...
by conservation scientist William Andrew Oddy in 1973, in order to test materials for safety in and around art objects.
Often, materials for construction and museum contexts (including artefact conservation) are evaluated for safety. However, though materials may be safe for building purposes, they may emit trace amounts of chemicals that can harm art objects over time. Acid
An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...
s, formaldehyde
Formaldehyde ( , ) (systematic name methanal) is an organic compound with the chemical formula and structure , more precisely . The compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde. It is stored as ...
, and other pollutants can damage and even destroy delicate artifacts if placed too close.
Procedure
This test calls for a sample of the material in question to be placed in an airtight container with threecoupons
In marketing, a coupon is a ticket or document that can be redeemed for a financial discount or rebate when purchasing a product.
Customarily, coupons are issued by manufacturers of consumer packaged goods
or by retailers, to be used in ...
of different metals—silver
Silver is a chemical element; it has Symbol (chemistry), symbol Ag () and atomic number 47. A soft, whitish-gray, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. ...
, lead
Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...
, and copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...
—that are not touching each other or the sample of the material. The container is sealed with a small amount of de-ionized water to maintain a high humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...
, then heated at 60 degrees Celsius
The degree Celsius is the unit of temperature on the Celsius temperature scale "Celsius temperature scale, also called centigrade temperature scale, scale based on 0 ° for the melting point of water and 100 ° for the boiling point ...
for 28 days. An identical container with three metal coupons acts as a control. If the metal coupons show no signs of corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
, then the material is deemed suitable to be placed in and around art objects. The Oddy test is not a contact test, but is for testing off-gassing.
Each metal detects a different set of corrosive agents
Corrosion is a Erosion, natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion ...
. The silver is for detecting reduced sulfur compounds and carbonyl sulfide
Carbonyl sulfide is the chemical compound with the linear formula . It is a colorless flammable gas with an unpleasant odor. It is a linear molecule consisting of a carbonyl double bonded to a sulfur atom. Carbonyl sulfide can be considered to ...
s. The lead is for detecting organic acids, aldehyde
In organic chemistry, an aldehyde () (lat. ''al''cohol ''dehyd''rogenatum, dehydrogenated alcohol) is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred ...
, and acidic gases. The copper is for detecting chloride
The term chloride refers to a compound or molecule that contains either a chlorine anion (), which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond (). The pr ...
, oxide, and sulfur compounds.
There are many types of materials testing
Materials testing is used to assess product quality, functionality, safety, reliability and toxicity of both materials and electronic devices. Some applications of materials testing include defect detection, failure analysis, material developmen ...
for other purposes, including chemical test
In chemistry, a chemical test is a qualitative property, qualitative or Quantitative property, quantitative procedure designed to identify, quantify, or characterise a chemical compound or substituent, chemical group.
Purposes
Chemical testing m ...
ing and physical test A physical test is a qualitative or quantitative procedure that consists of determination of one or more characteristics of a given product, process or service according to a specified procedure.ASTM E 1301, Standard Guide for Proficiency Testing ...
ing.
Development
The Oddy test has gone through many changes and refinements over time. Whereas Andrew Oddy proposed to place each metal coupon in a separate glass container with the material to be tested, Bamberger et al. proposed a "three-in-one" test, where all three metal coupons shared one container, simplifying the procedure. Robinett and Thickett (2003) refined the "three-in-one" test by stabilizing the metal coupons. One of the main issues with the Oddy test is that there is some subjectivity to the interpretation of the results, since it is primarily a visual determination. Some proposals have been made to use objective quantification methods for assessment of the results of the Oddy test.
Institutions that use the Oddy test in their research are mainly art museums such as The J. Paul Getty Museum, The Nelson-Atkins Museum of Art, and the Metropolitan Museum of Art
The Metropolitan Museum of Art, colloquially referred to as the Met, is an Encyclopedic museum, encyclopedic art museum in New York City. By floor area, it is the List of largest museums, third-largest museum in the world and the List of larg ...
.
References
Further reading
* * * Chemical tests Conservation and restoration of cultural heritage {{Biochem-stub