The Postcard
A postally unused postcard that was published by Reinthal & Newman, Publishers of New York. The card was printed in the United States.
Castor Oil
Castor oil is nothing to do with squeaky wheels on the legs of furniture (casters), although it can be used as a lubricant.
It is a vegetable oil pressed from castor beans. Castor oil is a colourless to very pale yellow liquid with a distinct taste and odour.
Castor oil and its derivatives are used in the manufacturing of soaps, lubricants, hydraulic and brake fluids, paints, dyes, coatings, inks, cold resistant plastics, waxes and polishes, nylon, pharmaceuticals and perfumes.
Composition of Castor Oil
Castor oil is a good source of ricinoleic acid, which makes it a valuable addition to feedstocks, commanding a higher price than other seed oils. As an example, in July 2007, Indian castor oil sold for about US$0.90 per kilogram, whereas U.S. soybean, sunflower and canola oils sold for US$0.30 per kilogram.
Uses of Castor Oil
Annually 270,000–360,000 tonnes of castor oil are produced for a variety of uses.
(a) Castor Oil in Food and Preservatives
In the food industry, food-grade castor oil is used in food additives, flavourings, sugar candy, and chocolate. It is also used in food packaging, and as a mould inhibitor.
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 castor oil for extended storage.
(b) Castor Oil in Traditional Medicine
The use of castor oil as a laxative is first referred to in the circa 1550 BC Ebers Papyrus, although it is known to have been in use for this purpose several centuries before then.
The United States Food and Drug Administration (FDA) has categorized castor oil as:
"Generally recognized as safe and
effective for over-the-counter use
as a laxative with its major site of
action the small intestine, where it
is digested into ricinoleic acid".
Although used in traditional medicine to induce labour in pregnant women, there is insufficient evidence that castor oil is effective in dilating the cervix or inducing labour.
Castor oil, or a castor oil derivative is an excipient added to prescription drugs; it acts as a vehicle or medium for an active ingredient. Medications in which castor oil features include:
- Miconazole, an antifungal agent
- Paclitaxel, a mitotic inhibitor used in cancer chemotherapy
- Sandimmune, an immunosuppressant drug widely used in connection with organ transplant to reduce the activity of the patient's immune system
- Nelfinavir mesylate, an HIV protease inhibitor
- Tacrolimus, an immunosuppressive drug
- Xenaderm ointment, a topical treatment for skin ulcers
- Aci-Jel (composed of ricinoleic acid from castor oil, with acetic acid and oxyquinoline), used to maintain the acidity of the vagina
- Optive Plus and Refresh Ultra, artificial tears to treat dry eye both contain castor oil
- Vishnevsky liniment also contains castor oil.
(c) Alternative Medicinal Use of Castor Oil
In naturopathy, castor oil is promoted as a treatment for several human health conditions, including cysts. 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."
(d) Castor Oil in Skin and Hair Care
Castor oil is used in cosmetic products including creams and moisturisers. Small amounts of castor oil are frequently used in soap to increase lathering in the finished bar. It has also been used to enhance hair conditioners and anti-dandruff products.
(e) The Use of Castor Oil in Coatings
Castor oil is used in the polyurethane industry, where it is widely used as a rigid polyol and in coatings. One particular use is in polyurethane concrete where a castor-oil emulsion is used with cement to make a construction aggregate. This is applied fairly thickly as a slurry which is self-levels to build a resilient floor.
It is not a drying oil, meaning that it has a low reactivity with air compared to oils such as linseed oil and tung oil.
(f) Castor Oil as a Precursor to Industrial Chemicals
Castor oil can be broken down into other chemical compounds that have numerous applications.
Transesterification followed by steam cracking gives undecylenic acid, a precursor to specialized polymer nylon 11, and heptanal, a component in fragrances.
Breakdown of castor oil gives 2-octanol, both a fragrance component and a specialized solvent.
Hydrogenation of castor oil produces a waxy lubricant.
Castor oil can be epoxidized to make the triglycidyl ether of castor oil which is useful in epoxy technology. This is available commercially as Heloxy.
The production of lithium grease consumes a significant amount of castor oil. Hydrogenation and saponification of castor oil yields a high performance lubricant grease.
Since it has a relatively high dielectric constant, highly refined and dried castor oil is sometimes used as a dielectric fluid within high performance high voltage capacitors.
(g) Castor Oil as a Lubricant
Vegetable oils are generally unattractive alternatives to petroleum-derived lubricants because of their poor oxidative stability. 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.
However, castor oil tends to form gums in a short time, and therefore its usefulness is limited to engines that are regularly rebuilt, such as racing engines. The 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.
(h) Early Aviation and Aeromodelling
World War I aviation engines 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.
Methanol-fuelled two-cycle engines used for aeromodelling, since their adoption by model airplane hobbyists in the 1940's, have used varying percentages of castor oil as a lubricant. 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 by using castor oil in small percentages can improve the pneumatic seal of the sleeve valve, improving the engine's performance over time.
(i) The Use of Castor Oil in Turkey Red Oil
Turkey red oil, also called sulphonated castor oil, is made by adding sulphuric acid to vegetable oils, most notably castor oil. It was the first synthetic detergent after ordinary soap.
(j) Castor Oil in Biodiesel
Castor oil, like 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.
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.
(k) Castor Oil as a Punishment
Some parents used to punish children with a dose of castor oil. Physicians recommended against the practice because they did not want medicines associated with punishment.
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. Belgian military officials prescribed heavy doses of castor oil in the Belgian Congo as a punishment for being too sick to work.
The most famous use of castor oil as punishment came in Fascist Italy under Benito Mussolini. It was a favourite tool used by the Blackshirts to intimidate and humiliate their opponents. Political dissidents were force-fed large quantities of castor oil by Fascist squads.
Victims of this treatment sometimes died, as the dehydrating effects of the oil-induced diarrhoea often complicated the recovery from the nightstick beating they also received along with the castor oil.
However, even those victims who survived had to bear the humiliation of the laxative effects resulting from excessive consumption of the oil. It is believed that the Nazi SA used this torture method against German Jews shortly after the appointment of Adolf Hitler as Chancellor of Germany in 1933.
It is said that Mussolini's power was backed by "The bludgeon and castor oil".
In lesser quantities, castor oil was also used as an instrument of intimidation, for example, to discourage civilians or soldiers who would call in sick.
Today, the Italian terms manganello and olio di ricino still carry strong political connotations. These words are still used to satirize patronizing politicians, or the authors of disliked legislation. They should be used with caution in common conversation. The terms Usare l'olio di ricino, ("to use castor oil") and usare il manganello ("to use the bludgeon") mean "to coerce or abuse", and can be misunderstood in the absence of proper context.
The Safety of Olive Oil
The castor seed contains ricin, a toxic lectin. Heating during the oil extraction process denatures and deactivates the lectin. However, harvesting castor beans may not be without risk.
The International Castor Oil Association FAQ document states that castor beans contain an allergenic compound called CB1A. This chemical is described as being virtually non-toxic, but has the capacity to sensitize 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.
These health issues, in addition to concerns about the toxic by-product (ricin) from castor oil production, have encouraged the quest for alternative sources for hydroxy fatty acids. Alternatively, some researchers are trying to genetically modify the castor plant to prevent the synthesis of ricin.
Since castor oil is sometimes used to induce labor in full-term pregnancies (scientific evidence of its effectiveness is lacking, however), consuming castor oil to treat constipation is not considered safe in pregnancies that are not at full term yet, as it may cause contractions of the womb.
