Rust preventive oil compositions are designed to resist corrosion by forming an oil film on the surface of the metal. The oil forms an effective barrier that obstructs the movement of oxygen, and water from reaching the surface.
A rust preventive oil composition may be used for a variety of metal members. It may be applied as a wash oil, or used for a long-term protection from rust.
For achieving the rust preventive property, the kinematic viscosity of the rust preventive oil composition must be within an acceptable range. Kinematic viscosity of rust preventive oil compositions is measured according to the method described in JIS K 2283. Generally, kinematic viscosity of rust prevention oils is between 6 mm2/s and 2.5 mm2/s.
To maintain a stable oil film on the surface of a metal member, a rust preventive oil composition may be mixed with a low-viscosity base oil. A low-viscosity base oil is characterized by its aromatic content of 3 mass % or less, and kinematic viscosity of 10 mm2/s or more. Combining a high-viscosity base oil with a low-viscosity one can extend the life of the oil solution.
Rust prevention oil compositions can be applied to the surface of a metal member by swabbing, brushing, or immersion application. In addition, a rust preventive oil composition can be used in a washing process to remove foreign bodies.
An oil solution containing an additive agent can be used to remove water from a metal surface. The performance of the additive agent is dependent on the viscosity of the rust preventive oils. When the viscosity is below the optimum level, the water removal property is compromised.