Distilling Turpentine from Pine Resin — The Essential Solvent of Oil Painting

MANDATORY SAFETY: Set up OUTDOORS or in a very well-ventilated area, away from buildings and ignition sources. Turpentine vapour is heavier than air, highly flammable, and accumulates at ground level. Use an electric hot plate or sand bath for heating — NEVER a gas burner or open flame near the still. Wear chemical-resistant gloves and safety goggles. Have a fire extinguisher (dry chemical type) and a bucket of sand within arm's reach. Ensure the distillation apparatus has NO sealed sections — the still must be able to vent; a sealed system under heat can explode. Check all joints and connections for leaks before heating.

Place 1 kg of crude pine resin (oleoresin) in the copper alembic still or glass distillation flask. Add 500 ml of water. The water serves as a carrier for steam distillation — the turpentine oil co-distills with the steam at a temperature below its normal boiling point (which would be 150-180°C if distilled alone). The still should never be more than two-thirds full — the resin foams during heating and needs headroom. Connect the condensing arm or tube to a coiled condenser (the 'worm'), which should be cooled with cold running water or immersed in a bucket of cold water. Place a collection vessel at the condenser outlet.

Apply gentle, even heat. As the temperature rises, the resin softens and dissolves in the hot water. At around 100°C, steam begins to carry turpentine oil vapour up through the still head and into the condenser. A mixture of water and turpentine oil begins to drip from the condenser outlet into the collection vessel. The distillate should flow as a steady, slow drip — not a stream. If it flows too fast, reduce the heat. The turpentine oil will float as a clear, slightly yellowish layer on top of the condensed water. Continue distilling until no more oily drops appear in the distillate — typically 1-2 hours for 1 kg of resin. The yield is approximately 15-25% turpentine oil by weight of the crude resin.

Let the collected distillate settle in a glass jar. The turpentine oil (density ~0.86 g/ml) floats clearly on top of the water. Carefully decant or siphon off the turpentine layer into a clean, dry glass bottle. The turpentine should be water-clear to pale yellow, with the sharp, clean, characteristic 'piney' smell. If cloudy, let it stand overnight — residual water droplets will settle out. Store in tightly sealed dark glass bottles away from heat and light. Pure turpentine is a superb solvent for oil paint, varnish resins (damar, mastic), and beeswax. It evaporates completely without residue.

After distillation is complete, let the still cool before opening. The residue in the still is rosin (colophony) — a hard, brittle, transparent amber-coloured resin. While still warm and liquid, pour it carefully through a coarse strainer (to remove bark, dirt, and insect debris) into a mould or onto a non-stick surface. Once cool, rosin sets to a hard, glassy solid that shatters when struck. Rosin is valuable in its own right: it is the material rubbed on violin bows, used as soldering flux, added to varnishes for hardness, and used to size paper. From 1 kg of crude pine resin, you should obtain approximately 150-250 g of turpentine oil and 700-800 g of rosin.