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556:(ignite) due to heat released during the curing process. This hazard is greater when oil-soaked materials are folded, bunched, or piled together, which allows heat to accumulate and accelerate the reaction. Precautions include: wetting rags with water and spreading them away from direct sunlight; keeping them in air-tight fireproof metal containers; immersing them in water inside air-tight metal containers designed for such applications; or storing them immersed in solvents in suitable closed containers.
332:, releasing individual fatty acids. In the case of paints, some portion of these free fatty acids (FFAs) 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
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network, often visible by formation of a skin-like film on samples. This polymerization results in stable films that, while somewhat elastic, do not flow or deform readily. Diene-containing fatty acid derivatives, such as those derived from linoleic acid, are especially prone to this reaction because
396:
intermediates. A series of addition reactions ensues. Each step produces additional free radicals, which then engage in further crosslinking. The process finally terminates when pairs of free radicals combine. The polymerization occurs over a period of days to years and renders the film dry to the
328:, for instance, increases in weight by 17 percent. As oxygen uptake ceases, the weight of the film declines as volatile compounds evaporate. As the oil ages, further transitions occur. A large number of the original ester bonds in the oil molecules undergo
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present in the pigment. The original network, with its nonpolar, covalent bonds, is replaced by an ionomeric structure, held together by ionic interactions. The structure of these ionomeric networks is not well understood.
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may play a role in plasticizing paint films, preventing them from becoming too brittle. Carboxyl groups in the polymers of the stationary phase ionize, becoming negatively charged and form complexes with metal
252:
Since oxidation is the key to curing in these oils, those that are susceptible to chemical drying are often unsuitable for cooking, and are also highly susceptible to becoming
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touch. Premature action of the drying agents causes skinning of the paint, this undesirable process is suppressed by the addition of antiskinning agents such as
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that hardens to a tough, solid film after a period of exposure to air, at room temperature. The oil hardens through a chemical reaction in which the components
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after heating in the absence of air. If the oil is subjected to raised temperatures for a long time, it will become a rubbery oil-insoluble substance.
656:
Ned A. Porter, Sarah E. Caldwell, Karen A. Mills "Mechanisms of free radical oxidation of unsaturated lipids" Lipids 1995, volume 30, Pages 277-290.
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The early stages of the drying process can be monitored by weight changes in an oil film. The film becomes heavier as it absorbs oxygen.
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in their original solvent whereas a cured oil paint or varnish does not. A dissolved wax or resin is recovered unchanged after the
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through autoxidation, the process by which fatty foods develop off-flavors. Rags, cloth, and paper saturated with drying oils may
276:, the addition of oxygen to an organic compound and the subsequent crosslinking. This process begins with an oxygen molecule (O
427:(bottom). The order of drying rate is alpha-linolenic > linoleic > oleic acid, reflecting their degree of unsaturation.
707:
van den Berg, Jorit D.J. "Mobile and
Stationary Phases in Traditional Aged Oil Paint". www.amolf.nl 2002. MOLART. 8 May 2006
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460:
in the oil. Oils with an iodine number greater than 130 are considered drying, those with an iodine number of 115–130 are
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Representative triglyceride found in a drying oil. The triester is derived from three different unsaturated fatty acids,
563:, a 38-story office building, which resulted in severe structural damage, and eventually the demolition of the building.
500:, consist of long, spaghetti-like strands of hydrocarbon molecules, which interlace and compact but do not interconnect (
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Leaving linseed-oil-soaked rags in a pile after refinishing woodwork was the cause of a 1991 fire in
Philadelphia's
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318:. In the second step, the hydroperoxide combines with another unsaturated side chain to generate a crosslink.
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Friedman, Ann, et al. "Painting". www.worldbookonline.com. 2006. 46 Stetson St. #5 Brookline, MA. 10 May 2006
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are susceptible to crosslinking reactions. Bonds form between neighboring fatty acid chains, resulting in a
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Simplified chemical reactions associated with cobalt-catalyzed drying process. In the first step, the
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radicals. Monounsaturated fatty acids, such as oleic acid, are slower to undergo drying because the
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The ability of drying oils to form strong strong but flexible films is very useful in
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adjacent to one of the double bonds within the unsaturated fatty acid. The resulting
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The drying process is accelerated by certain metal salts, especially derivatives of
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to make the complexes oil-soluble. These catalysts speed up the reduction of the
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of fatty acids. These esters are characterized by high levels of
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radical intermediates are less stable (i.e., slower to form).
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Using linseed oil (a drying oil) and pigment for painting
622:
Ulrich Poth (2002). "Drying Oils and
Related Products".
700:"History of Oil Paint". www.cyberlipid.org. 5 May 2006
694:"Autoxidation". McGraw Hill Encyclopedia. 8th ed. 1997.
464:, and those with an iodine number of less than 115 are
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Rags, cloth, and paper saturated with drying oils may
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Drying oils, boiled oil, and solid and liquid driers
381:. These salts are derived from the carboxylates of
280:) in the air inserting into carbon-hydrogen (C-H)
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471:
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625:Ullmann's Encyclopedia of Industrial Chemistry
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680:. London: Leonard Hill Limited. p. 14.
268:The "drying", hardening, or, more properly,
716:. London: Scott, Greenwood & Co., 1901.
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221:. Some commonly used drying oils include
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213:). Drying oils are a key component of
16:Oil that hardens after exposure to air
345:Most drying oils rapidly increase in
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516:do so by chemically changing them.
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314:undergoes autoxidation to give a
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264:Chemistry of the drying process
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472:Comparison to waxes and resins
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702:(archived 16 September 2009)
369:. In technical terms, these
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249:resins and other binders.
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272:of oils is the result of
753:Wood finishing materials
634:10.1002/14356007.a09_055
399:methylethyl ketone oxime
678:Printing Ink Technology
628:. Weinheim: Wiley-VCH.
433:Drying oils consist of
353:Role of metal catalysts
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375:coordination complexes
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743:Visual arts materials
727:Tung and Linseed Oils
554:combust spontaneously
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379:homogeneous catalysts
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258:spontaneously combust
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710:Andés, Louis Edgar,
676:Apps, E. A. (1958).
532:. In former times,
480:, such as hard-film
450:alpha-linolenic acid
729:by Steven D. Russel
201:) by the action of
142:Polyunsaturated fat
137:Monounsaturated fat
748:Painting materials
662:10.1007/BF02536034
561:One Meridian Plaza
484:or paste wax, and
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209:of water or other
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371:oil drying agents
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334:mobile phase
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274:autoxidation
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197:(and hence,
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542:linseed oil
510:evaporation
462:semi-drying
446:fatty acids
425:oleic acids
326:Linseed oil
295:pentadienyl
235:perilla oil
223:linseed oil
207:evaporation
104:Cooking oil
737:Categories
609:References
578:Danish oil
536:, rich in
534:walnut oil
526:oil paints
488:, such as
466:non-drying
388:, such as
383:lipophilic
330:hydrolysis
243:walnut oil
239:castor oil
199:polymerize
187:drying oil
123:Components
94:Drying oil
23:Plant oils
573:Blown oil
530:varnishes
502:crosslink
363:manganese
347:viscosity
219:varnishes
217:and some
215:oil paint
195:crosslink
147:Trans fat
114:Biodiesel
99:Oil paint
588:Linoleum
567:See also
482:carnauba
435:glycerol
417:linoleic
227:tung oil
211:solvents
598:Varnish
506:soluble
498:shellac
419:(top),
339:cations
299:allylic
290:polymer
640:
548:Safety
496:, and
490:dammar
486:resins
439:esters
359:cobalt
270:curing
254:rancid
203:oxygen
189:is an
494:copal
478:waxes
365:, or
312:diene
282:bonds
247:alkyd
45:Types
758:Oils
638:ISBN
528:and
373:are
367:iron
241:and
109:Fuel
86:Uses
77:list
67:list
57:list
658:doi
630:doi
437:tri
191:oil
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