White spirit [CAS 64475-85-0][1][2][3], also known as Stoddard solvent [CAS 8052-41-3][4][5] or mineral spirits, is a paraffin-derived clear, transparent liquid which is a common organic solvent used in painting and decorating. In 1924, Atlanta dry cleaner W. J. Stoddard worked with Lloyd E. Jackson of the Mellon Institute of Industrial Research to develop a less volatile dry cleaning solvent as an alternative to the petroleum solvents in use. Dry cleaners began using the result of their work in 1928 and it soon became the predominant dry cleaning solvent in the United States, until the late 1950s.
It is a mixture of aliphatic and alicyclic C7 to C12 hydrocarbons with a maximum content of 25% of C7 to C12 aromatic hydrocarbons. A typical composition for mineral spirits is > 65% C10 or higher hydrocarbons[6], aliphatic solvent hexane, and a maximum aromatic hydrocarbon content of 0.1% by volume, a kauri-butanol value of 29, an initial boiling point of 149 °F (65 °C), a dry point of approximately 156 °F (69 °C), and a density of 0.7 g/cc.
Stoddard solvent is a specific mixture of hydrocarbons, typically > 65% C10 or higher hydrocarbons [7].
White spirit is used as an extraction solvent, as a cleaning solvent, as a degreasing solvent and as a solvent in aerosols, paints, wood preservatives, lacquers, varnishes, and asphalt products. In western Europe about 60% of the total white spirit consumption is used in paints, lacquers and varnishes. White spirit is the most widely used solvent in the paint industry. In households, white spirit is commonly used to clean paint brushes after use.
Three different types and three different grades of white spirit exist. The type refers to whether the solvent has been subjected to hydrodesulfurization (removal of sulfur) alone (type 1), solvent extraction (type 2) or hydrogenation (type 3). Each type comprises three different grades: low flash grade, regular grade, and high flash grade. The grade is determined by the crude oil used as the starting material and the conditions of distillation.
In addition there is type 0, which is defined as distillation fraction with no further treatment, consisting predominantly of saturated C9 to C12 hydrocarbons with a boiling range of 140–200 °C.
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White Spirit is a petroleum distillate that is used as a paint thinner and mild solvent. In industry, mineral spirits is used for cleaning and degreasing machine tools and parts. According to Wesco, a supplier of solvents and cleaning equipment, mineral spirits "are especially effective in removing oils, greases, carbon, and other material from metal." Mineral spirits may also be used in conjunction with cutting oil as a thread cutting and reaming lubricant.
Artists use mineral spirits as an alternative to turpentine since it is less flammable and less toxic. Because of interactions with pigments, artists require a higher grade of mineral spirits than many industrial users, including the complete absence of residual sulfur. Odorless Mineral Spirits are mineral spirits that have been further refined to remove the more toxic aromatic compounds, and are recommended for applications such as oil painting, where humans have close contact with the solvent.
In screen printing (also referred to as silk-screening), mineral spirits are often used to clean and unclog screens after printing with oil-based textile and plastisol inks. They are also used to thin inks used in making monoprints.
Mineral spirits are often used inside liquid-filled compasses and gauges.
The physical properties of the three types of white spirit are:
Property | T1: Low flash | T2: Regular | T3: High flash |
---|---|---|---|
Initial boiling point (IBP) (°C) | 130–144 | 145–174 | 175–200 |
Final boiling point (°C) | IBP+21, max. 220 | ||
Average relative molecular mass | 140 | 150 | 160 |
Relative density (15 °C) | 0.765 | 0.780 | 0.795 |
Flash point (°C) | 21–30 | 31–54 | > 55 |
Vapour pressure (kPa, 20 °C) | 1.4 | 0.6 | 0.1 |
Volatility (n-butyl acetate=1) | 0.47 | 0.15 | 0.04 |
Autoignition temperature (°C) | 240 | 240 | 230 |
Explosion limits (Flammable Range) (% by volume in air) | 0.6–6.5 | 0.6–6.5 | 0.6–8 |
Vapour density (air=1) | 4.5–5 | 4.5–5 | 4.5–5 |
Refractive index (at 20 °C) | 1.41–1.44 | 1.41–-1.44 | 1.41–1.44 |
Viscosity (cps, 25 °C) | 0.74–1.65 | 0.74–1.65 | 0.74–1.65 |
Solubility (% by weight in water) | < 0.1 | < 0.1 | < 0.1 |
Kauri-butanol value | 29–33 | 29–33 | 29–33 |
Aniline point (°C) | 60–75 | 60–75 | 60–75 |
Reactivity | reaction with strong oxidizing agents | ||
Odor threshold (mg/m3) | — | 0.5–5 | 4 |
White spirit is mainly classed as an irritant. It has a fairly low acute toxicity by inhalation of the vapour, dermal (touching the skin) and oral routes (ingestion). However, acute exposure can lead to central nervous system depression resulting in lack of coordination and slowed reactions. Exposure to very high concentrations in enclosed spaces can lead to general narcotic effects (drowsiness, dizziness, nausea etc...) and can eventually lead to unconsciousness. Oral ingestion presents a high aspiration hazard. Prolonged or repeated skin exposure over a long period of time can result in severe irritant dermatitis, also called contact dermatitis. Exposure to large amounts of white spirit in direct contact with the skin (e.g. being soaked with 2 litres) for several hours can cause severe chemical burns.[8] It is recommended that skin exposure be kept to a minimum by use of gloves, and that hands be washed after contact. Occasional exposure to skin is highly unlikely to cause any problems.
Exposure to an average white spirit concentration of 240 mg/m3 (40 ppm) for more than 13 years could lead to chronic central nervous system effects. White spirit is implicated in the development of "chronic toxic encephalopathy" among house painters.
Owing to the volatility and low bioavailability of its constituents, white spirit, although it is moderately toxic to aquatic organisms, is unlikely to present significant hazards to the environment. It should not however, be purposely poured down the sink or freshwater drain. It should be disposed of correctly wherever possible.