White spirit
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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 drycleaner named W. J. Stoddard worked with Lloyd E. Jackson of the Mellon Research Institute to develop specifications for a less volatile drycleaning solvent as an alternative to more volatile petroleum solvents. Drycleaners began using it in 1928 and it was the predominant drycleaning 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.
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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[edit] 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 (% 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 |
[edit] See also
[edit] References
- World Health Organisation safety sheet
- Chemicals Used In Drycleaning Operations - Environmental Enlightenment
