Most white oils are derived from paraffinic base oils, he said, but there are a number of naphthenic white oils in the market as well. Medicinal white oils offered for sale in Europe are defined by the European Pharmacopoeia, a consolidation of national formulary standards from Germany, France and Great Britain. European Pharmacopoeia specifies two groups of medicinal oils, and industry people describe them as light and heavy, Lawford noted.

These have similar specifications. In technical terms there are definitions for Paraffinum perliquidum and Paraffinum liquidum. These are very low in acidity and highly dewaxed. The big difference is the viscosity, which is measured dynamically and ranges from about 12 to 32 centiStokes at 40 degrees C for the former, and 42 to 85 cSt for the latter.

As per these definitions, products which do not meet the above criteria cannot be classified as true medicinal white oils, Lawford said. Another restriction is that the addition of Vitamin E as an antioxidant in the medicinal grade is not explicitly allowed in Europe.

U.S. Pharmacopeia has very similar performance to the European, Lawford continued. One major difference is that Americans allow the use of antioxidants. Vitamin E is a food-grade antioxidant, [but] with its application European white oil producers cannot claim to meet the continents Pharmacopeia standards.

White oils hoping to satisfy the medicinal criteria must undergo a battery of rigorous tests, he related. They include identification tests, saponification and acidity tests, tests for relative density, and viscosity tests. One key assay uses ultraviolet absorbance to test for polyaromatic hydrocarbons (PAH), to assure that the oil is very low in these unhealthy compounds. Also there are so-called readily carbonizables and solid paraffins tests, Lawford continued. For the latter, a sample of the fluid is immersed in ice water for four hours and should remain clear; if not, that can signal the presence of solid paraffins.

Technical Grades

Unlike their medicinal counterparts, no European specifications define the characteristics of technical white oils, Lawford said. However, the U.S. Food and Drug Administration has a whole series of classifications that include technical white oils, and these are referenced worldwide.

Under the CFR 21 178.3620(b) regulation, the FDA defines technical white oil suitable for use in manufacturing of products intended for incidental contact with food, he said, adding that the quality of technical white oils is only just below that of medicinal white oil.

Differences between the technical and medicinal white oil grades include a relaxation of the color requirements, and some relaxation of the PAH requirement, which in the technical version can be approximately eight times whats permitted in the medicinal grade, according to Lawford.

Many companies wanting to register a white oil for use as a component in food-grade lubricants will turn to the not-for-profit NSF International in Ann Arbor, Mich., which will review the product for adherence to FDA and U.S. Department of Agriculture guidelines. If it complies, the white oil can be listed in the NSFs online White Book, Lawford noted, and buyers can feel assured of its suitability for making finished lubricants for this market. NSF has a definition for food-grade oils, marked as H-1, or HX-1 for the components that go into food-grade oils.

Abundant Uses

Medical grade white oils can be used in all pharmaceutical applications, as well as cosmetics such as lotions, baby oil and cremes. They are colorless, odorless and tasteless. They are often used in making lubricants for canning and bottling lines and other equipment, where the lubricant may inadvertently come into contact with food or beverages. Elsewhere in the food industry, white oils are used as dough divider oils, release agents and constituents of both coatings and wrapping papers. These white oils are safe to ingest in limited quantities, and they were even used as a laxative many years ago, according to some producers.

Europes White Oil Producers

White oils also are used in general industry, and in household and textile products. As low-viscosity white mineral oils they find application in areas such as furniture polishes, rust preventives, and as inert carriers for insecticide sprays.

In the textile industry, white mineral oils provide lubricity and oxidative stability, reducing the likelihood of staining. The color-sensitive plastics and polyethylene industries also use them in extrusion equipment and compressors.

White oils are further used in agriculture as crop spray oils, and in production of animal feeds. In adhesive products, they extend the adhesiveness, reduce melt viscosity and plasticize formulations.

How Theyre Made

Sources of white oils vary, and they are processed in two principal pathways. The first, more conventional process is acid treatment of base oil to remove impurities, using a mineral oil feed-stock with sulfuric acid. This process was first used in the last century, in Russia, Lawford said. Acid treatment was the original process used when white oils were first produced in the early 20th century.

However, this process suffers from producing large quantities of acid sludge, which white oil refiners then have the problem of disposing. On the other hand, the process has the advantage of producing high-value sulfonates, which are used in many lubricant additive applications, he observed, adding that a number of companies sell this useful byproduct.

A more modern way of producing white oils is to put vacuum gas oil feedstock through the various stages of severe hydrocracking followed by hydrotreatment and polishing. At the end of one set of processes, technical white oil is produced. Further hydrogenation and hydrotreatment leads to a distillation of medicinal white oils, Lawford said.

Since the development of two-stage hydrotreating in the 1970s, this route to making white oils has become the more widely used, as it can process larger volumes of feedstock faster and more cheaply, Lawford noted. This is the process employed by the worlds largest white oil producers, such as Petro-Canada (now Suncor) and ExxonMobil. Both companies have their own operations in Europe, situated in the Netherlands and France, respectively. Other important European white oils producers are the German company H & R, Sonneborn in the Netherlands, Italys RAM Oil, and Aemedsa in Spain.

SIP, which has 20,000 metric tons of specialty oil storage around Europe, including a custom-built white oils storage facility in Antwerp, Belgium, estimates that the continents market for white oils includes 150,000 metric tons of medicinal oils and 60,000 tons of technical white oils a year. That makes them an important part of Europes overall process oil market, which amounts to another 630,000 tons annually. But Lawford cautioned that actual volumes are difficult to gauge because end-use applications are often blurred.

Future Supply

Over the past few years, white oil supply in Europe has out-stripped demand for the product in traditional markets like pharmaceuticals, cosmetics or food, commoditizing this market, Lawford observed. Medicinal applications only consume around 50 percent of the medicinal white oil capacity. However, heavy medicinal white oils have found application in the process oil sector in recent years. Paraffinum liquidum, of the 68 to 100 cSt viscosity grades, has become more and more scarce.

SIP is seeing less feedstock available for making heavy white oil grades, as API Group I base oil production declines in Europe and elsewhere. (This, added Lawford, is affecting the entire process oil market, which needs substantial volumes of bright stock, which are also in short supply.) Taking Group Is place are newer refineries that make API Group III and gas-to-liquids base oils, but do not produce heavy molecules. They make lighter grades, which remain plentiful, but these trends are leading to a decline of heavy grades, Lawford emphasized.

Although white oil has been commoditized, quite a few challenges make it relatively hard for new players to enter the market. The first barrier is storage and transport. In addition, the approvals for marketing to white oil applications can be long and arduous, especially for medicinal products, Lawford said. As manufacturers migrate away from Europe toward the Far East there is some evidence that the continents white oil market is declining.

Domestic production dominates current European supply while material coming from Asia and the subcontinent has found its way into circulation as well.