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A drying oil is an oil which hardens to a tough, solid film after a period of exposure to air. The term "drying" is actually somewhat of a misnomer, since the oil does not harden through the evaporation of water or other solvents, but through a chemical reaction in which oxygen is absorbed from the environment (autoxidation). Drying oils are a key component of oil paint and many varnishes. Some commonly used drying oils include linseed oil, tung oil, poppy seed oil, perilla oil and walnut oil. Plant oils are oils derived from plant sources, as opposed to animal fats or petroleum. ...
[1] This image has been released into the public domain by the copyright holder. ...
Vegetable fats and oils are substances composed of triglycerides, derived from plants. ...
Olive oil The following is intended to be a comprehensive list of oils that are extracted from plants. ...
An essential oil is a concentrated, hydrophobic liquid containing volatile aromatic compounds extracted from plants. ...
Essential oils are extracted by distillation. ...
Maceration (from Latin maceratus, past participle of macerare, to soften) may refer to: extreme leanness usually caused by starvation or disease a solution prepared by soaking plant material in vegetable oil or water the steeping of grape skins and solids in must, where alcohol acts as a solvent to extract...
Commercially-available macerated oils include all these, and others. ...
View of Delft in oil paint, by Johannes Vermeer. ...
It has been suggested that this article or section be merged with vegetable oil. ...
Use of vegetable oil directly as a fuel is one of the most environmentally friendly sources of power, as it is carbon neutral, and unlike biodiesel does not require energy input to perform transesterification or produce glycerine as a waste product. ...
Biodiesel refers to a diesel-equivalent, processed fuel derived from biological sources. ...
Aromatherapy, commonly associated with complementary and alternative medicine (CAM), is the use of volatile liquid plant materials, known as essential oils (EOs), and other aromatic compounds from plants to purportedly affect a persons mood or health. ...
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ...
Saturated fat is fat that consists of triglycerides containing only saturated fatty acids. ...
In nutrition, monounsaturated fats are fatty acids with one double-bonded carbon in the molecule, with all of the others single-bonded carbons, in contrast to polyunsaturated fatty acids which have more than one double bond. ...
An unsaturated fat is a fat or fatty acid in which there is one or more double bonds between carbon atoms of the fatty acid chain. ...
A trans fatty acid (commonly shortened to trans fat) is an unsaturated fatty acid molecule that contains a trans double bond between carbon atoms, which makes the molecule less kinked compared to cis fat. Research suggests a correlation between diets high in trans fats and diseases like atherosclerosis and coronary...
Natural olive oil Synthetic motor oil Oil, in a general sense, is a chemical compound that is not miscible with water, and is in a liquid state at ambient temperatures. ...
This article or section is in need of attention from an expert on the subject. ...
A solvent is a fluid phase (liquid, gas, or plasma) that dissolves a solid, liquid, or gaseous solute, resulting in a solution. ...
General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ...
Autoxidation is any oxidation that occurs in open air or in presence of oxygen and/or UV radiation and forms peroxides and hydroperoxides. ...
View of Delft in oil paint, by Johannes Vermeer. ...
Varnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. ...
Linseed oil is a yellowish drying oil derived from the dried ripe seeds of the flax plant (Linum usitatissimum, Linaceae). ...
Tung oil is used as a wood finishing product. ...
Poppyseed oil (also poppy seed oil or poppy oil) is oil extracted from the seeds of the opium poppy ( The whole seeds of the poppy plant are edible and non-toxic, and have been used for cooking (particularly baking) since ancient times. ...
Perilla oil is obtained from the seeds of perennial herbs of the genus Perilla, usually Perilla frutescens. ...
Walnut oil was one of the most important and vital oils of the Renaissance. ...
Drying oil composition Drying oils are characterized by high levels of polyunsaturated fatty acids. One common measure of the siccative (drying) property of oils is iodine number. Oils with an iodine number greater than 130 are considered drying, those with an iodine number of 115-130 are semi-drying, and those with an iodine number of less than 115 are non-drying. A polyunsaturated organic compound is one in which more than one double bond exists within the representative molecule. ...
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ...
The iodine number in chemistry is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. ...
A semi-drying oil is an oil which partially hardens when it is exposed to air. ...
A non-drying oil is an oil which does not harden when it is exposed to air. ...
Drying process The "drying", hardening, or, more properly, curing of oils is the result of an exothermic reaction in the form of autoxidation and is chemically equivalent to slow, flameless combustion. In this process, oxygen attacks the hydrocarbon chain, touching off a series of addition reactions. As a result, the oil polymerizes, forming long, chain-like molecules. Following the autoxidation stage, the oil polymers cross-link: bonds form between neighboring molecules, resulting in a vast polymer network. Conceptually, this network equates to a fusing of individual, randomly interlocking, strands into a cohesive mass or, in the case of varnishes and paints, into a solid film. Over time, this network may undergo further change. Certain functional groups in the networks become ionized, and the network transitions from a system held together by nonpolar covalent bonds to one governed by the ionic forces between these functional groups and the metal ions present in the pigment. In polymer chemistry and Process Engineering, curing refers to the toughening or hardening of a polymer material by cross-linking of polymer chains, brought about by chemical additives, ultraviolet radiation, Electron beam (EB) or heat. ...
In thermodynamics, the word exothermic describes a process or reaction that releases energy in the form of heat. ...
Autoxidation is any oxidation that occurs in open air or in presence of oxygen and/or UV radiation and forms peroxides and hydroperoxides. ...
Combustion or burning is a complex sequence of chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. ...
General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ...
Polymer is a term used to describe large molecules consisting of repeating structural units, or monomers, connected by covalent chemical bonds. ...
In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ...
In organic chemistry, functional groups are specific groups of atoms within molecules, that are responsible for the characteristic chemical reactions of those molecules. ...
An ion is an atom or group of atoms that normally are electrically neutral and achieve their status as an ion by loss or addition of one or more electrons. ...
Vegetable oils consist of glycerol esters of fatty acids, long hydrocarbon chains with a terminal carboxyl group. In oil autoxidation, oxygen attacks a hydrocarbon chain, often at the site of an allylic hydrogen (a hydrogen on a carbon atom adjacent to a double bond). This produces a free radical, a substance with an unpaired electron which makes it highly reactive. A series of addition reactions ensues. Each step produces additional free radicals, which then engage in further polymerization. The process finally terminates when free radicals collide, combining their unpaired electrons to form a new bond. The polymerization stage occurs over a period of days to weeks, and renders the film dry to the touch. Glycerol, also well known as glycerin and glycerine, and less commonly as propane-1,2,3-triol, 1,2,3-propanetriol, 1,2,3-trihydroxypropane, glyceritol, and glycyl alcohol is a colorless, odorless, hygroscopic, and sweet-tasting viscous liquid. ...
For the Biblical Ester, see Esther. ...
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated. ...
In chemistry, a carboxyl group is a functional group consisting of a carbon atom doubly bonded to an oxygen atom and single-bonded to a hydroxyl (-OH) group, typically written as -COOH: where R is a hydrogen or an organic group. ...
In chemistry free radicals are uncharged atomic or molecular species with unpaired electrons or an otherwise open shell configuration. ...
The electron is a fundamental subatomic particle that carries an electric charge. ...
Chemical changes in the paint film continue as time passes; the polymer chains begin to cross-link. Adjacent molecules form covalent bonds resulting in a molecular network, called the stationary phase, that extends throughout the oil. Molecules are no longer free to slide past each other or to move apart. In terms of paint or varnish, the stationary phase is the equivalent to a stable film which, while somewhat elastic, does not flow or deform under the pull of gravity. Covalent bonding is a description of chemical bonding that is characterized by the sharing of one or more electrons between two atoms. ...
During the drying process, a number of compounds are produced that do not contribute to the polymer network. These include unstable hydroperoxides (ROOH), the major by-product of the reaction of oxygen with unsaturated fatty acids. The hydroperoxides quickly decompose, forming carbon dioxide and water, as well as a variety of aldehydes, acids, and hydrocarbons. Many of these compounds are volatile, and in an unpigmented oil, they would be quickly lost to the environment. However, in paints, such volatiles may react with lead, zinc, copper or iron compounds in the pigment, and remain in the paint film as coordination complexes or salts. A large number of the original ester bonds in the oil molecules undergo hydrolysis, releasing individual fatty acids. Some portion of the free fatty acids react with metals in the pigment, producing metal carboxylates. Together, the various non-cross-linking substances associated with the polymer network constitute the mobile phases. Unlike the molecules that are part of the network itself, they are capable of moving and diffusing within the film, and can be removed using heat or a solvent. The mobile phase may play a role in plasticizing the paint film, preventing it from becoming too brittle. Organic peroxides are organic molecules containing the peroxide functional group ROOR If the R is hydrogen, the compound is called organic hydroperoxide. ...
An aldehyde. ...
An acid (often represented by the generic formula HA) is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a pH of less than 7. ...
Hydrocarbons are refined at oil refineries and processed at chemical plants A hydrocarbon is a chemical compound that consists only of the elements carbon (C) and hydrogen (H). ...
Hydrolysis is a chemical reaction or process in which a molecule is split into two parts by reacting with a molecule of water, which has the chemical formula H2O. One of the parts gets an OH- from the water molecule and the other part gets an H+ from the water. ...
One simple technique for monitoring the early stages of the drying process is to measure weight change in an oil film over time. Initially, the film becomes heavier, as it absorbs large amounts of oxygen. Then oxygen uptake ceases, and the weight of the film declines as volatile compounds are lost to the environment.
As the oil ages, a further transition occurs. Carboxyl groups in the polymers of the stationary phase lose a hydrogen ion, becoming negatively charged, and form complexes with metal cations present in the pigment. The original network, with its nonpolar, covalent bonds is replaced by an ionomeric structure, held together by ionic interactions. At present, the structure of these ionomeric networks is not well understood.
Prior to polymerization or curing, drying oils consist of medium length hydrocarbon chain molecules that are joined at one end by a triglyceride and in shape are partially hooked or kinked. By contrast, non-"drying" waxes, such as hard-film carnauba or paste wax, and resins, such as dammar, copal, and shellac, consist of long, spaghetti-like strands of hydrocarbon molecules which interlace and compact but do not form covalent bonds in the manner of drying oils. Thus, waxes and resins are re-dissoluble whereas a cured oil varnish or paint is not. This is the article about the process. ...
In polymer chemistry and Process Engineering, curing refers to the toughening or hardening of a polymer material by cross-linking of polymer chains, brought about by chemical additives, ultraviolet radiation or heat. ...
It has been suggested that Medium Chain Triglycerides be merged into this article or section. ...
Wax has traditionally referred to a substance that is secreted by bees (beeswax) and used by them in constructing their honeycombs. ...
Carnauba is a wax derived from the leaves of a plant native to northeastern Brazil, the Carnauba Palm (Copernica cerifera). ...
Resin of a pine Insect trapped in resin. ...
Dammar gum is obtained from the Dipterocarpaceae family of trees in India and East Asia, principally those of the genera Shorea, Balanocarpus, or Hopea. ...
Shellac is a brittle or flaky secretion of the lac insect Coccus lacca, found in the forests of Assam and Thailand. ...
Hydrocarbons are refined at oil refineries and processed at chemical plants A hydrocarbon is a chemical compound that consists only of the elements carbon (C) and hydrogen (H). ...
Covalent bonding is a form of chemical bonding characterized by the sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together. ...
Safety Rags, cloth, and paper saturated with drying oils may combust spontaneously (catch on fire) due to heat given off during the curing process. This is especially the case where oil-soaked materials are folded, bunched, compressed, or piled together, which allows the heat to accumulate and even accelerate the reaction. Precautions include: wetting the rags with water and spreading them to dry in a safe place away from direct sunlight; closing them off completely in water inside air-tight metal containers designed for such applications; or storing them immersed in solvents in suitable closed containers.
References - “Autoxidation.” McGraw Hill Encyclopedia. 8th ed. 1997.
- Flanders, Peggy J. “How Oils Dry.” www.peggyflanders.com. 5 May 2006 <http://www.peggyflanders.com/Information/how_oils_dry.htm>
- Friedman, Ann, et. al. “Painting.” www.worldbookonline.com. 2006. 46 Stetson St. #5 Brookline, MA. 10 May, 2006 <http://www.worldbookonline.com/wb/Article?id=ar410780>
- “History of Oil Paint.” www.cyberlipid.org. 5 May 2006 <http://www.cyberlipid.org/perox/oxid0011.htm>
- Mecklenburg, Marion. "Autoxidation of Oil" 13 Jan 2006. www.thepaintershandbook.org. Mark David Gottsegen. 11 June 2006 <http://www.thepaintershandbook.org/forums/viewtopic.php?p=59&sid=1af793cece44ccf8743ba531850d0cda>
- van den Berg, Jorit D.J. “Mobile and Stationary Phases in Traditional Aged Oil Paint.” www.amolf.nl 2002. MOLART. 8 May 2006 <http://www.nwo.nl/nwohome.nsf/pages/NWOP_62WDAG/$file/molart%20eindverslag.pdf>
See also View of Delft in oil paint, by Johannes Vermeer. ...
A semi-drying oil is an oil which partially hardens when it is exposed to air. ...
There are very few or no other articles that link to this one. ...
Wood finishing refers to the process of embellishing and/or protecting the surface of wooden objects. ...
Varnish is a transparent, hard, protective finish or film primarily used in wood finishing but also for other materials. ...
External links - Tung and Linseed Oils by Steven D. Russel
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