castor oil

The name probably comes from a confusion between the Ricinus plant that produces it and another plant, the Vitex agnus-castus.{{cite news

| url=https://www2.palomar.edu/users/warmstrong/plmar99.htm

| title=The Castor Bean: A Plant Named After A Tick

| publisher=Wayne's Word: An Online Textbook of Natural History

| date=March 1999

| access-date=2020-04-26

| archive-date=2021-11-15

| archive-url=https://web.archive.org/web/20211115044547/https://www2.palomar.edu/users/warmstrong/plmar99.htm

| url-status=dead

}}{{Cite book |last=Jacob |first=Irene |title=The Healing Past |chapter-url=https://brill.com/view/book/edcoll/9789004377325/BP000006.xml |chapter=Ricinus Communis—The Miracle Tree through Four Thousand Years |date=1993-01-01 |publisher=BRILL |isbn=978-90-04-37732-5 |editor-last=Jacob |pages=81–93 |doi=10.1163/9789004377325_006 |editor-last2=Jacob |archive-date=2022-06-21 |access-date=2024-11-22 |archive-url=https://web.archive.org/web/20220621202144/https://brill.com/view/book/edcoll/9789004377325/BP000006.xml |url-status=live }} An alternative etymology, though, suggests that it was used as a replacement for castoreum.{{cite web |url-status= usurped |url= http://www.billcasselman.com/cwod_archive/beaver_castor_two.htm |archive-url= https://web.archive.org/web/20110203042939/http://www.billcasselman.com/cwod_archive/beaver_castor_two.htm |archive-date= 2011-02-03 |title= Castor |work= Bill Casselman's Canadian Word of the Day |last= Casselman |first= William Gordon |access-date= 2014-08-09 }}

Use of castor oil as a laxative is attested to in the {{circa|1550 BCE}} Ebers Papyrus,{{cite book |last=Bryan |first=Cyril P. |date=1930 |title=The Papyrus Ebers, Translated from the German Version by Cyril P. Bryan |url=http://oilib.uchicago.edu/books/bryan_the_papyrus_ebers_1930.pdf |archive-url=https://web.archive.org/web/20130921055114/http://oilib.uchicago.edu/books/bryan_the_papyrus_ebers_1930.pdf |archive-date=2013-09-21 |location=London |publisher=Geoffrey Bles |page=44 }} and it was in use several centuries earlier.Bryan, p. xvii Midwifery manuals from the 19th century recommended castor oil and 10 drops of laudanum for relieving "false pains."{{Cite web |last=Barnes |first=Robert Sydenham Fancourt |title=A Manual of Midwifery for Midwives |edition=2nd |location=London |year=1883 |url=https://babel.hathitrust.org/cgi/pt?id=hvd.hc4qpg&seq=102 |access-date=2024-08-17 |via=HathiTrust |language=en-gb |archive-date=2024-08-17 |archive-url=https://web.archive.org/web/20240817071057/https://babel.hathitrust.org/cgi/pt?id=hvd.hc4qpg&seq=102 |url-status=live }}

Image:Castor oil (Main Component Structural Formulae) V2.svg

Castor oil is well known as a source of ricinoleic acid, a monounsaturated, 18-carbon fatty acid. Among fatty acids, ricinoleic acid is unusual in that it has a hydroxyl functional group on the 12th carbon atom. This functional group causes ricinoleic acid (and castor oil) to be more polar than most fats. The chemical reactivity of the alcohol group also allows chemical derivatization that is not possible with most other seed oils.

Because of its ricinoleic acid content, castor oil is a valuable chemical in feedstocks, commanding a higher price than other seed oils. As an example, in July 2007, Indian castor oil sold for about US$0.90/kg ($0.41/lb),{{citation needed|date=August 2019}} whereas U.S. soybean, sunflower, and canola oils sold for about $0.30/kg ($0.14/lb).{{cite web|url=http://www.fas.usda.gov/oilseeds/circular/2007/July/oilseedsfull0707.pdf |date=July 2007 |title=Seed Oil Prices |publisher=United States Department of Agriculture |page=31 |access-date=2008-08-10 |url-status=dead |archive-url=https://web.archive.org/web/20080406064840/http://www.fas.usda.gov/oilseeds/circular/2007/July/oilseedsfull0707.pdf |archive-date=April 6, 2008 }}

Castor oil has been used orally to relieve constipation or to evacuate the bowel before intestinal surgery.{{cite web |title=Castor oil |url=https://www.drugs.com/monograph/castor-oil.html |publisher=Drugs.com |access-date=20 April 2023 |date=3 October 2022 |archive-date=20 April 2023 |archive-url=https://web.archive.org/web/20230420203550/https://www.drugs.com/monograph/castor-oil.html |url-status=live }} The laxative effect of castor oil is attributed to ricinoleic acid, which is produced by hydrolysis in the small intestine. Use of castor oil for simple constipation is medically discouraged because it may cause violent diarrhea.

In the food industry, food-grade castor oil is used in food additives, flavorings, candy (e.g., polyglycerol polyricinoleate in chocolate),{{Cite journal |last1= Wilson |first1= R |last2= Van Schie |first2= BJ |last3= Howes |first3= D |title= Overview of the preparation, use and biological studies on polyglycerol polyricinoleate (PGPR) |journal= Food and Chemical Toxicology |volume= 36 |issue= 9–10 |pages= 711–8 |year= 1998 |pmid= 9737417 |doi= 10.1016/S0278-6915(98)00057-X}} as a mold inhibitor, and in packaging. Polyoxyethylated castor oil (e.g., Kolliphor EL){{cite web|url=http://www.sfm.state.or.us/cr2k_subdb/msds/cremophor_el_castor_oil.pdf|title=Safety datawsheet cremophor El Castor Oil|website=www.sfm.state.or.us|access-date=2016-12-05|archive-date=2017-12-06|archive-url=https://web.archive.org/web/20171206224827/http://www.sfm.state.or.us/cr2k_subdb/msds/cremophor_el_castor_oil.pdf|url-status=dead}} is also used in the food industries.{{Cite journal |doi= 10.1590/S0001-37652004000100005 |last1= Busso |first1= C |last2= Castro-Prado |first2= MA |title= Cremophor EL stimulates mitotic recombination in uvsH/uvsH diploid strain of Aspergillus nidulans |journal= Anais da Academia Brasileira de Ciências |volume=76 |issue=1 |pages=49–55 |date=March 2004 |pmid=15048194 |doi-access= free }} In India, Pakistan, and Nepal, food grains are preserved by the application of castor oil. It stops rice, wheat, and pulses from rotting. For example, the legume pigeon pea is commonly available coated in oil for extended storage.

File:Scott & Bowne's Palatable Castor Oil.jpg

Castor oil has been used in cosmetic products included in creams and as a moisturizer. It is often combined with zinc oxide to form an emollient and astringent, zinc and castor oil cream, which is commonly used to treat infants for nappy rash.{{cite book |last1=Williams |first1=Cheryll |title=Medicinal Plants in Australia Volume 3: Plants, Potions and Poisons |date=1 July 2012 |publisher=Rosenberg Publishing |isbn=978-1-925078-07-7 |page=309 |url=https://books.google.com/books?id=ieVUAQAAQBAJ&pg=PA309 |access-date=8 March 2023 |language=en |archive-date=20 April 2023 |archive-url=https://web.archive.org/web/20230420114645/https://books.google.com/books?id=ieVUAQAAQBAJpg=PA309 |url-status=live }}{{cite book |last1=Nathan |first1=Alan |title=Non-prescription Medicines |date=2010 |publisher=Pharmaceutical Press |isbn=978-0-85369-886-9 |page=206 |url=https://books.google.com/books?id=lW-0IoSYMBYC&dq=zinc+and+castor+oil+cream&pg=PA206 |access-date=8 March 2023 |language=en |archive-date=20 April 2023 |archive-url=https://web.archive.org/web/20230420114755/https://books.google.com/books?id=lW-0IoSYMBYC&dq=zinc+and+castor+oil+cream&pg=PA206 |url-status=live }}

Castor oil is used as a vehicle for serums administering steroid hormones such as estradiol valerate via intramuscular or subcutaneous injection.{{Cite journal |last1=Huber |first1=C. Riffkin R. |last2=Keysser |first2=C. H. |date=1964-08-01 |title=Castor Oil as a Vehicle for Parenteral Administration of Steroid Hormones |url=https://www.sciencedirect.com/science/article/abs/pii/S0022354915344890 |journal=Journal of Pharmaceutical Sciences |volume=53 |issue=8 |pages=891–895 |doi=10.1002/jps.2600530809 |pmid=14241800 |issn=0022-3549}}{{Cite web |title=ESTRADIOL VALERATE INJECTION, USP Rx Only |url=https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=2984bce2-89bf-4768-a1ca-ccf03b1197be&type=display |access-date=2024-12-16 |website=dailymed.nlm.nih.gov}}

Despite the lack of evidence, castor oil is sometimes claimed to be able to cure diseases. According to the American Cancer Society, "available scientific evidence does not support claims that castor oil on the skin cures cancer or any other disease."{{cite web |date=March 2011 |title=Castor Oil |url=http://www.cancer.org/treatment/treatmentsandsideeffects/complementaryandalternativemedicine/manualhealingandphysicaltouch/castor-oil |archive-url=https://web.archive.org/web/20130209065404/http://www.cancer.org/treatment/treatmentsandsideeffects/complementaryandalternativemedicine/manualhealingandphysicaltouch/castor-oil |archive-date=2013-02-09 |access-date=2013-09-22 |publisher=American Cancer Society}}

File:Huile de ricin naturafro.jpg

Despite some undesirable side effects, castor oil is used for labor induction. There is no high-quality research proving that ingestion of castor oil results in cervical ripening or induction of labor; there is, however, evidence that taking it causes nausea and diarrhea. A systematic review of "three trials, involving 233 women, found there has not been enough research done to show the effects of castor oil on ripening the cervix or inducing labour or compare it to other methods of induction. The review found that all women who took castor oil by mouth felt nauseous. More research is needed into the effects of castor oil to induce labour."{{Cite journal |doi = 10.1002/14651858.CD003099.pub2 |title= Castor oil, bath and/or enema for cervical priming and induction of labour |journal= Cochrane Database of Systematic Reviews |year= 2013 |issue= 7 |page= CD003099 |last1= Kelly |first1= AJ |last2= Kavanagh |first2= J |last3= Thomas |first3= J |volume= 2013 |pmid=23881775|pmc= 7138266 }}{{cite journal |vauthors=Carlson NS, Dunn Amore A, Ellis JA, Page K, Schafer R |title=American College of Nurse-Midwives Clinical Bulletin Number 18: Induction of Labor |journal=J Midwifery Women's Health |volume=67 |issue=1 |pages=140–149 |date=January 2022 |pmid=35119782 |pmc=9026716 |doi=10.1111/jmwh.13337 |type=Review |quote=Despite its long history of use for inducing onset of spontaneous labor, castor oil has minimal evidence to support its efficacy and is commonly associated with adverse effects of nausea, vomiting, and diarrhea.}} Castor oil is still used for labor induction in environments where modern drugs are not available; a review of pharmacologic, mechanical, and "complementary" methods of labor induction published in 2024 by the American Journal of Obstetrics and Gynecology stated that castor oil's physiological effect is poorly understood but "given gastrointestinal symptomatology, a prostaglandin mediation has been suggested but not confirmed."{{cite journal |vauthors=Sanchez-Ramos L, Levine LD, Sciscione AC, Mozurkewich EL, Ramsey PS, Adair CD, Kaunitz AM, McKinney JA |title=Methods for the induction of labor: efficacy and safety |journal=Am J Obstet Gynecol |volume=230 |issue=3S |pages=S669–S695 |date=March 2024 |pmid=38462252 |doi=10.1016/j.ajog.2023.02.009 |type=Review|doi-access=free }} According to Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk (2008), castor oil should not be ingested or used topically by pre-term pregnant women.{{Cite book |last1=Briggs |first1=Gerald G. |chapter-url=https://books.google.com/books?id=YOEV2w3XTxsC&dq=%22castor+oil%22+abortifacient&pg=PA271 |title=Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk |last2=Freeman |first2=Roger K. |last3=Yaffe |first3=Sumner J. |date=2008 |publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-7876-3 |pages=271–273 |language=en |chapter=Castor Oil (Laxative/Oxytocic)}} There is no data on the potential toxicity of castor oil for nursing mothers.

File:Kellogg's Perfected Tasteless Castor Oil, Spencer Kellogg and Sons Inc., New York 03.jpg, New York]]

Since children commonly strongly dislike the taste of castor oil, some parents punished children with a dose of it.For an American example see {{cite book|author=David J. Rothman|title=Conscience and Convenience: The Asylum and Its Alternatives in Progressive America|url=https://books.google.com/books?id=BfCrAAAAQBAJ&pg=PA279|year=1980|publisher=Transaction Publishers|page=279|access-date=2015-10-29|isbn=9780202365091|archive-date=2023-01-14|archive-url=https://web.archive.org/web/20230114165300/https://books.google.com/books?id=BfCrAAAAQBAJ&pg=PA279|url-status=live}}For a Canadian examples see {{cite book|author=Neil Sutherland|title=Growing Up: Childhood in English Canada from the Great War to the Age of Television|url=https://archive.org/details/growingupchildho0000suth|url-access=registration|year=1997|publisher=University of Toronto Press|page=[https://archive.org/details/growingupchildho0000suth/page/87 87]|access-date=2015-10-29|isbn=9780802079831}} Physicians recommended against the practice because it may associate medicines with punishment and make children afraid of the doctor.{{cite book|title=Journal of the American Medical Association|url=https://books.google.com/books?id=Mp0hAQAAMAAJ&pg=PA1699|year=1919|publisher=American Medical Association.|page=1699|access-date=2015-10-29|archive-date=2023-01-14|archive-url=https://web.archive.org/web/20230114165301/https://books.google.com/books?id=Mp0hAQAAMAAJ&pg=PA1699|url-status=live}}

A heavy dose of castor oil could be used as a humiliating punishment for adults. Colonial officials used it in the British Raj (India) to deal with recalcitrant servants.{{cite book|author=Cecilia Leong-Salobir|title=Food Culture in Colonial Asia: A Taste of Empire|url=https://books.google.com/books?id=Q0a4QLN1CQgC&pg=PA66|year=2011|publisher=Taylor & Francis|page=66|isbn=9781136726545|access-date=2016-01-08|archive-date=2023-01-14|archive-url=https://web.archive.org/web/20230114165305/https://books.google.com/books?id=Q0a4QLN1CQgC&pg=PA66|url-status=live}}

Belgian military officials prescribed heavy doses of castor oil in Belgian Congo as a punishment for being too sick to work.{{Cite book|title=King Leopold's ghost: a story of greed, terror, and heroism in Colonial Africa|last=Adam.|first=Hochschild|date=1999|publisher=Houghton Mifflin|isbn=978-0547525730|edition=1st Mariner books|location=Boston|pages=166|oclc=759834634}} Castor oil was also a tool of punishment favored by the Falangist and later Francoist Spain during and following the Spanish Civil War.{{Cite book |last=Preston |first=Paul |url=http://archive.org/details/spanishholocaust0000pres |title=The Spanish holocaust : inquisition and extermination in twentieth-century Spain |date=2012 |publisher=New York : W.W. Norton & Co. |others=Internet Archive |isbn=978-0-393-06476-6 |pages=139, 156, 169, 187, 201, 202, 212, 310, 315, 321, 326, 449}} Its use as a form of gendered violence to repress women was especially prominent.{{Cite web |last=Juan |first=Carmen Miguel |date=2016-04-06 |title=Mujeres y dictadura franquista: la historia silenciada |url=https://www.eldiario.es/contrapoder/mujeres-dictadura-franquista_132_4067401.html |access-date=2023-12-16 |website=elDiario.es |language=es |archive-date=2023-12-16 |archive-url=https://web.archive.org/web/20231216201135/https://www.eldiario.es/contrapoder/mujeres-dictadura-franquista_132_4067401.html |url-status=live }}

This began during the war where Nationalist forces would specifically target Republican-aligned women, both troops and civilians, who lived in Republican-controlled areas.

The forced drinking of castor oil occurred alongside sexual assault, rape, torture and murder of these women. Its most notorious use as punishment came in Fascist Italy under Benito Mussolini. It was a favorite tool used by the Blackshirts to intimidate and humiliate their opponents.{{cite encyclopedia|title=Italy The rise of Mussolini |encyclopedia=Encyclopædia Britannica Online |publisher=Encyclopædia Britannica |year=2007 |url=http://britannica.com/eb/article-27762/Italy |access-date=2007-08-03 |url-status=dead |archive-url=https://web.archive.org/web/20071014023531/http://britannica.com/eb/article-27762/Italy |archive-date=October 14, 2007 }}{{Cite news | title =Benito's Birthday | publisher =Time, in partnership with CNN | date = August 6, 1923 | url =http://www.time.com/time/magazine/article/0,9171,716284,00.html?iid=chix-sphere | archive-url =https://web.archive.org/web/20080407195821/http://www.time.com/time/magazine/article/0,9171,716284,00.html?iid=chix-sphere | url-status =dead | archive-date =April 7, 2008 | access-date =2007-08-03 }}{{Cite book | last =Bosworth | first =R. J. B. | title =Mussolini | publisher =Arnold/Oxford Univ. Press | year= 2002 | location =New York | isbn =978-0-340-73144-4 }}

Political dissidents were force-fed large quantities of castor oil by fascist squads so as to induce bouts of extreme diarrhea in the victims. This technique was said to have been originated by Gabriele D'Annunzio or Italo Balbo."Bearded like a medieval condottiere, bluff yet suave, fearless and supple, [Italo Balbo] was not the type to pass unnoticed anywhere. His admirers here chose to forget the Blackshirt club-wielder and reputed inventor of the castor-oil treatment for Fascist foes"
[https://www.nytimes.com/1940/07/01/archives/marshal-balbo.html Marshal Balbo] {{Webarchive|url=https://web.archive.org/web/20210429102059/https://www.nytimes.com/1940/07/01/archives/marshal-balbo.html |date=2021-04-29 }}, The New York Times, July 1, 1940, p. 18. This form of torture was potentially deadly, as the administration of the castor oil was often combined with nightstick beatings, especially to the rear, so that the resulting diarrhea would not only lead to dangerous dehydration but also infect the open wounds from the beatings. However, even those victims who survived had to bear the humiliation of the laxative effects resulting from excessive consumption of the oil.{{cite web |author=Cecil Adams |url=https://www.straightdope.com/21342121/did-mussolini-use-castor-oil-as-an-instrument-of-torture |title=Did Mussolini use castor oil as an instrument of torture? |publisher=The Straight Dope |date=1994-04-22 |access-date=2014-08-09 |archive-date=2020-11-01 |archive-url=https://web.archive.org/web/20201101021504/https://www.straightdope.com/21342121/did-mussolini-use-castor-oil-as-an-instrument-of-torture |url-status=live }}

Castor oil is used as a biobased polyol in the polyurethane industry. The average functionality (number of hydroxyl groups per triglyceride molecule) of castor oil is 2.7, so it is widely used as a rigid polyol and in coatings.

One particular use is in a polyurethane concrete where a castor-oil emulsion is reacted with an isocyanate (usually polymeric methylene diphenyl diisocyanate) and a cement and construction aggregate. This is applied fairly thickly as a slurry, which is self-levelling. This base is usually further coated with other systems to build a resilient floor.{{Cite journal|last=Howarth|first=GA|date=June 2003|title=Polyurethanes, polyurethane dispersions and polyureas: Past, present and future|journal=Surface Coatings International Part B: Coatings Transactions|language=en|volume=86|issue=2|pages=111–118|doi=10.1007/bf02699621|s2cid=93574741|issn=1476-4865}} Castor oil is not a drying oil, meaning that it has a low reactivity with air compared with oils such as linseed oil and tung oil. However, dehydration of castor oil yields linoleic acids, which do have drying properties.

In this process, the OH group on the ricinoleic acid along with a hydrogen from the next carbon atom are removed, forming a double bond which then has oxidative cross-linking properties and yields the drying oil. It is considered a vital raw material.{{Cite journal |last=Ogunniyi |first=D. S. |date=2006-06-01 |title=Castor oil: A vital industrial raw material |url=https://www.sciencedirect.com/science/article/pii/S0960852405002026 |journal=Bioresource Technology |language=en |volume=97 |issue=9 |pages=1086–1091 |doi=10.1016/j.biortech.2005.03.028 |pmid=15919203 |bibcode=2006BiTec..97.1086O |issn=0960-8524 |access-date=2023-03-09 |archive-date=2016-11-30 |archive-url=https://web.archive.org/web/20161130045802/http://www.sciencedirect.com/science/article/pii/S0960852405002026 |url-status=live }}

Castor oil can react with other materials to produce other chemical compounds that have numerous applications.{{Cite journal |last1=Ma |first1=Yufeng |last2=Wang |first2=Rui |last3=Li |first3=Qiaoguang |last4=Li |first4=Mei |last5=Liu |first5=Chengguo |last6=Jia |first6=Puyou |date=2021-03-24 |title=Castor oil as a platform for preparing bio-based chemicals and polymer materials |url=https://www.icevirtuallibrary.com/doi/10.1680/jgrma.20.00085 |journal=Green Materials |volume=10 |issue=3 |pages=99–109 |doi=10.1680/jgrma.20.00085 |s2cid=233687152 |issn=2049-1220 |access-date=2022-04-18 |archive-date=2023-01-31 |archive-url=https://web.archive.org/web/20230131222012/https://www.icevirtuallibrary.com/doi/10.1680/jgrma.20.00085 |url-status=live }}{{cite web|url=http://whc-oils.com/castor-oil.html|title=Multiple uses of castor oil|access-date=2007-08-02|archive-date=2007-09-29|archive-url=https://web.archive.org/web/20070929062813/http://whc-oils.com/castor-oil.html|url-status=dead}}{{cite journal|title=Castor oil as a renewable resource for the chemical industry |date=2010-01-25 |doi=10.1002/ejlt.200900138 |volume=112 |journal=European Journal of Lipid Science and Technology |pages=10–30|last1 = Mutlu|first1 = Hatice|last2=Meier |first2=Michael A. R. }}{{Cite journal|last=Ogunniyi |first=D.S. |date=June 2006 |title=Castor oil: A vital industrial raw material |journal=Bioresource Technology |volume=97 |issue=9 |pages=1086–91 |doi=10.1016/j.biortech.2005.03.028 |pmid=15919203 |bibcode=2006BiTec..97.1086O }}

Transesterification followed by steam cracking gives undecylenic acid, a precursor to specialized polymer nylon 11, and heptanal, a component in fragrances.Ashford's Dictionary of Industrial Chemicals, Third edition, 2011, page 6162

Breakdown of castor oil in strong base gives 2-octanol, both a fragrance component and a specialized solvent, and the dicarboxylic acid sebacic acid. Hydrogenation of castor oil saturates the alkenes, giving a waxy lubricant.

Castor oil may be epoxidized by reacting the OH groups with epichlorohydrin to make the triglycidyl ether of castor oil which is useful in epoxy technology.{{Cite book|url=https://books.google.com/books?id=XiRdDgAAQBAJ&q=Heloxy+505&pg=PA157|title=Polymeric Thermosetting Compounds: Innovative Aspects of Their Formulation Technology|last=Hermansen|first=Ralph D.|date=2017-03-16|publisher=CRC Press|isbn=9781771883153|language=en|access-date=2020-11-09|archive-date=2023-01-14|archive-url=https://web.archive.org/web/20230114165300/https://books.google.com/books?id=XiRdDgAAQBAJ&q=Heloxy+505&pg=PA157|url-status=live}}

This is available commercially as Heloxy 505.{{cite book |last1=Ash |first1=Michael |last2=Ash |first2=Irene |title=Handbook of fillers, extenders, and diluents |publisher=Synapse Information Resources |location=Endicott, NY |isbn=9781890595968 |page=82 |edition=2nd|year=2007 }}

The production of lithium grease consumes a significant amount of castor oil. Hydrogenation and saponification of castor oil yields 12-hydroxystearic acid, which is then reacted with lithium hydroxide or lithium carbonate to give high-performance lubricant grease.{{Cite book|title=Kirk-Othmer Encyclopedia of Chemical Technology |url=https://www.scribd.com/doc/30116043/Castor-Oil |access-date=2010-07-12 |url-status=dead |archive-url=https://web.archive.org/web/20110714101239/http://www.scribd.com/doc/30116043/Castor-Oil |archive-date=July 14, 2011 }}

Since it has a relatively high dielectric constant (4.7), highly refined and dried castor oil is sometimes used as a dielectric fluid within high-performance, high-voltage capacitors.

File:Advertisement from The Aerial Age Weekly in 1921 - 002.jpg

Vegetable oils such as castor oil are typically unattractive alternatives to petroleum-derived lubricants because of their poor oxidative stability.{{cite web |url= http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=166442 |title=Directed synthesis of base oils that overcome traditional vegetable oil shortcomings|author-first1=Terry|author-last1=Isbell|publisher=Society of Tribologists and Lubrication Engineers|date=May 20, 2004|access-date= 2007-08-02 |archive-date= 2006-10-01 |archive-url= https://web.archive.org/web/20061001013304/http://ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=166442 |url-status= live }}{{cite web |url= http://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/oil.html#Environment |title= Petroleum Oil and the Environment |publisher= DOE |access-date= 2006-12-28 |archive-date= 2009-08-23 |archive-url= https://web.archive.org/web/20090823080443/http://www.eia.doe.gov/kids/energyfacts/sources/non-renewable/oil.html#Environment |url-status= live }} Castor oil has better low-temperature viscosity properties and high-temperature lubrication than most vegetable oils, making it useful as a lubricant in jet, diesel, and racing engines.{{cite web|last=McGuire |first=Nancy |title=Taming the Bean |publisher=The American Chemical Society |year=2004 |url=http://www.chemistry.org/portal/a/c/s/1/feature_pro.html?id=c373e9faf603d46b8f6a4fd8fe800100 |access-date=2007-08-02 |url-status=dead |archive-url=https://web.archive.org/web/20060927062935/http://www.chemistry.org/portal/a/c/s/1/feature_pro.html?id=c373e9faf603d46b8f6a4fd8fe800100 |archive-date=September 27, 2006 }} The viscosity of castor oil at 10 °C is 2,420 centipoise,{{cite book |last1= Brady |first1= George S. |title= Materials Handbook |year= 1997 |publisher= McGraw-Hill |location= New York |isbn= 978-0070070844 |edition= 14th |last2= Clauser |first2= Henry R. |last3= Vaccari |first3= John |url-access= registration |url= https://archive.org/details/materialshandboo14geor }} but it tends to form gums in a short time, so its usefulness is limited to engines that are regularly rebuilt, such as racing engines. Lubricant company Castrol took its name from castor oil.

Castor oil has been suggested as a lubricant for bicycle pumps because it does not degrade natural rubber seals.{{Cite book |last= Older |first= Jules |title= Backroad and Offroad Biking |publisher= Stackpole Books |location= Mechanicsburg, PA |year= 2000 |page= 37 |isbn= 978-0811731508}}

Turkey red oil, also called sulphonated (or sulfated) castor oil, is made by adding sulfuric acid to vegetable oils, most notably castor oil. It was the first synthetic detergent after ordinary soap. It is used in formulating lubricants, softeners, and dyeing assistants.{{cite book |last1=Penda |first1=H |title=Herbal Soaps & Detergents Handbook |date=2017 |publisher=NIIR |location=Delhi, India |isbn=9789381039007 |page=121}}

Castor oil, like currently less expensive vegetable oils, can be used as feedstock in the production of biodiesel. The resulting fuel is superior for cold winters, because of its exceptionally low cloud point and pour point.Biodiesel from Castor Oil: A Promising Fuel for Cold Weather [http://www.icrepq.com/full-paper-icrep/222-barajas.pdf (PDF)] {{webarchive |url=https://web.archive.org/web/20130616073236/http://www.icrepq.com/full-paper-icrep/222-barajas.pdf |date=June 16, 2013 }} by Carmen Leonor Barajas Forero, 2004-10-12. Retrieved 2012-01-24.

Initiatives to grow more castor for energy production, in preference to other oil crops, are motivated by social considerations. Tropical subsistence farmers would gain a cash crop.[http://www.biodieselmagazine.com/articles/622/the-promise-of-the-castor-bean The Promise of the Castor Bean] {{webarchive |url=https://web.archive.org/web/20160309162746/http://www.biodieselmagazine.com/articles/622/the-promise-of-the-castor-bean |date=March 9, 2016 }} by Elizabeth Johnson, Biodiesel Magazine, 2004-12-01. Retrieved 2012-01-24.

File:Le Rhone 9C.jpg used castor oil as a primary lubricant, mixed with the fuel]]

Castor oil was the preferred lubricant for rotary engines, such as the Gnome engine after that engine's widespread adoption for aviation in Europe in 1909. It was used almost universally in rotary-engined Allied aircraft in World War I. Germany had to make do with inferior ersatz oil for its rotary engines, which resulted in poor reliability.{{cite book |last= Guilmartin |first= John F. Jr. |title= Two Historians in Technology and War |year= 1994 |publisher= United States Army War College, Strategic Studies Institute |isbn= 978-1428915220 |page= 10 |chapter= Technology and Strategy: What Are the Limits?}}{{cite book |last= Fisher |first= Suzanne Hayes |title= The European Powers in the First World War: An Encyclopedia |year= 1999 |publisher= Taylor & Francis |isbn= 978-0815333517 |page= 10 |chapter= Aircraft, production during the war |editor-first1= Spencer C. |editor-last1= Tucker |editor-first2= Laura Matysek |editor-last2= Wood |editor-first3= Justin D. |editor-last3= Murphy }}{{cite book |title= Tariff Information Surveys on the Articles in Paragraphs 44 and 45 of the Tariff Act of 1913 |year= 1921 |author= U.S. Tariff Commission |page=40 |publisher= Government Printing Office |location= Washington, D.C. |author-link= United States Tariff Commission }}

The methanol-fueled, two-cycle, glow-plug engines used for aeromodelling, since their adoption by model airplane hobbyists in the 1940s, have used varying percentages of castor oil as lubricants. It is highly resistant to degradation when the engine has its fuel-air mixture leaned for maximum engine speed. Gummy residues can still be a problem for aeromodelling powerplants lubricated with castor oil, however, usually requiring eventual replacement of ball bearings when the residue accumulates within the engine's bearing races. One British manufacturer of sleeve valved four-cycle model engines has stated the "varnish" created{{fact|date=January 2025}} by using castor oil in small percentages can improve the pneumatic seal of the sleeve valve, improving such an engine's performance over time.

The castor seed contains ricin, a toxic lectin. Heating during the oil extraction process denatures and deactivates the lectin. Harvesting castor beans, though, may not be without risk.{{Cite journal |last1=Auld |first1= DL |last2= Pinkerton |first2= SD |last3= Rolfe |first3= R |last4= Ghetie |first4= V |last5= Lauterbach |first5= BF |display-authors= 4 |title= Selection of castor for divergent concentrations of ricin and ricinus communis agglutinin |journal= Crop Science |volume= 39 |pages=353–7 |date= March–April 1999 |url=http://crop.scijournals.org/cgi/content/abstract/39/2/353 |archive-url= https://web.archive.org/web/20081012215450/http://crop.scijournals.org/cgi/content/abstract/39/2/353 |archive-date=2008-10-12 |doi= 10.2135/cropsci1999.0011183X003900020008x|access-date=2007-07-31 |issue=2}} The International Castor Oil Association FAQ document states that castor beans contain an allergenic compound called CB1A. This chemical is described as being virtually nontoxic, but has the capacity to affect people with hypersensitivity. The allergen may be neutralized by treatment with a variety of alkaline agents. The allergen is not present in the castor oil itself.{{cite web | last=Dierig | first=David A. | title=Lesquerella | work=New Crop FactSHEET | publisher=Center for New Crops & Plant Products, at Purdue University | year=1995 | url=http://www.hort.purdue.edu/newcrop/cropfactsheets/Lesquerella.html | access-date=2007-08-01 | archive-date=2007-10-25 | archive-url=https://web.archive.org/web/20071025022951/http://www.hort.purdue.edu/newcrop/cropfactsheets/Lesquerella.html | url-status=live }}

• Botanol, a flooring material derived from castor oil
• Castor wax
• List of unproven and disproven cancer treatments
• [Https://healthsastra.in/castor-oil-benefits/ Castor Oil Benefits]

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• {{Kirk-Othmer|title=Castor Oil|last=Naughton |first=Frank|doi=10.1002/0471238961.0301192014012107.a01.pub2|mode=cs1|postscript=none}} – overview of chemical properties and manufacturing of castor oil

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