Substrate Terpenes are non-reactive with metals and most types of plastics. Strong terpene solutions can swell or degrade some types of plastic and rubber, so experimentation is recommended. Process Terpenes have really caught on for cleaning electronic assemblies and printed circuit boards. If properly rinsed, terpenes are compatible with painting and plating operations and are now commonly used in machine shops and engine rebuilding operations, especially in solvent sinks. High purity terpene solutions are popular for cleaning precision parts and high voltage electrical parts.
Experts debate whether unrinsed terpenes leave residues.
High purity terpenes don't leave a residue but do take longer to dry than chlorinated solvents. Low purity terpenes also dry slowly, but the impurities will remain as a residue. Also be aware that terpene cleaners or terpene rinse water may attack PVC plumbing in your cleaning equipment. Hazards Terpenes are flammable so spraying is not recommended, except in specially designed equipment. Terpenes are not highly volatile, but they are VOCs and may be regulated under the new Clean Air Act.