Definitions

White spirit

White spirit

White spirit, also known as Stoddard solvent, is a paraffin-derived clear, transparent liquid which is a common organic solvent used in painting and decorating. In 1924, an Atlanta dry cleaner named W. J. Stoddard worked with Lloyd E. Jackson of the Mellon Research Institute to develop specifications for a less volatile dry cleaning solvent as an alternative to more volatile petroleum solvents. Dry cleaners began using it in 1928 and it was the predominant dry cleaning solvent in the United States from the late 1920s until the late 1950s.

It is a mixture of saturated aliphatic and alicyclic C7 to C12 hydrocarbons with a maximum content of 25% of C7 to C12 alkyl aromatic hydrocarbons.

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 decorating. Its paint thinning properties enable brushes to be properly cleaned (by preventing the paint from hardening and ruining the bristles) and therefore enabling them to be re-used.

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.

Physical properties

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
Odour threshold (mg/m3) - 0.5-5 4

Toxicity

White spirit is mainly classed as an Irritant.

White spirit 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. It is highly recommended that skin exposure is kept to a minimum by use of gloves and that hands are washed after coming into contact with it. 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 if avoidable. It should be disposed of correctly wherever possible.

See also

References

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