Siccative

A siccative is a substance added to oil paint to help it dry faster.

1. A siccative is a substance that accelerates the drying of oil-based paints, varnishes, and mediums. It works mainly by helping the oil react with oxygen and form a solid film more quickly.

   In painting, siccatives are usually added in very small quantities. Too much can cause problems such as excessive brittleness, wrinkling, darkening, or uneven drying.

Siccatives are particularly relevant to oil painting because traditional drying oils do not simply evaporate like water. They gradually harden through a chemical reaction with oxygen, called oxidation. A siccative helps speed up this process.

Commercial products may contain metal compounds, often called metal driers. Historically, lead, cobalt, and manganese compounds have been used for this purpose, although some traditional driers require careful handling because of their toxicity.

Because excessive siccative can damage the paint film, it is generally better to use it sparingly and according to the manufacturer’s instructions.

• Speeds drying: helps oil paint harden more quickly.
• Acts chemically: accelerates the oxidation and hardening of drying oils.
• Used sparingly: too much can weaken or damage the paint film.
• Common in oil painting: especially when controlling drying time is important.