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PAINTING MATERIALS

this is regulated by outside factors, including temperature, atmospheric pressure,
humidity, ventilation, and amount of liquid surface exposed. Internally there are
definite factors also—vapor tension, surface tension, latent heat of evaporation,

ico

FIGURE 2. Evaporation rate curves of intermediate to slow liquids, adapted from those
of A. K. Doolittle, 'Lacquer Solvents in Commercial Use/ Industrial and Engineering
Chemistry, XXVII (1935), P* II7°j £fi»- 2- According to number, these are as follows:

1. Methyl cellosolve

2. Steam distilled turpentine

3. w-Butanol

4. Gum spirits turpentine

5. Amyl alcohol (mixed isomers)
6*. Cellosolve

7. Cellosolve acetate

8. V. M. and P. naphtha

9. Mineral spirits

10. Diacetone alcohol

11. Butyl cellosolve

12. Butyl lactate

specific heat, dissolved impurities, and a few others. Although vapor pressure and
evaporation rate are closely related, they are not the same. Vapor pressure is the
pressure (expressed in millimeters of mercury) when a liquid and its vapor are in
equilibrium in a closed system at a definite temperature. Vapor molecules in air