Understanding solvents is family affair

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Understanding solvents is family affair
Lacquer thinner
Solvents for water-based finishes
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Solvents are difficult to understand because they all look alike in the can. To make sense of them, and especially to understand lacquer thinner, which is the most important solvent for fast-drying finishes, it helps to organize the solvents into families.

There are five:

  • Petroleum distillates (mineral spirits, naphtha, etc.)

  • Alcohols (methanol, denatured alcohol, etc.)

  • Ketones (acetone, MEK, etc.)

  • Esters (butyl acetate, amyl acetate, etc.)

  • Glycol ethers (butyl cellosolve, butyl carbitol, etc.)

Petroleum distillates
Petroleum distillates dissolve wax, thin and clean up oils and varnishes, and are the ingredients in most furniture polishes. This family is the easiest to understand because we are familiar with so many of the individual solvents.

If you organize common petroleum distillates by their evaporation rates from fastest to slowest, you come up with the following:

  • Methane: already evaporated to a gas at room temperature

  • Propane: also a gas at room temperature

  • Butane: almost a gas at room temperature

  • Heptane and octane used in gasoline: very fast evaporating liquids

  • Naphtha: reasonably fast evaporating

  • Mineral spirits: fairly slow evaporating

  • Kerosene: almost no evaporation

  • Mineral oil: doesn’t evaporate at room temperature

  • Paraffin wax: a solid at room temperature

Toluene and xylene are the strong and smelly parts of naphtha and mineral spirits, and are chemically removed to leave odorless mineral spirits. Toluene and xylene evaporate very rapidly.

Turpentine is a distillate of pine-tree sap and is similar to mineral spirits in evaporation rate. The two can be used interchangeably in most situations.

Each of the other solvent families contains many individual solvents, which can be arranged by evaporation rate in the same manner.