The cleaning of surfaces is also possible by means of customized plasma technologies. There are a variety of different plasma generation methods that are currently in use, including, radio frequencies (40 kHz and 13,56 MHz) and microwaves. The typical gas mixtures used in cleaning contain oxygen, argon and sometimes hydrogen and carbon-tetra-fluoride. The mixture depends on the specific cleaning challenge including surface contamination on the actual substrate material.

There are no limitations concerning the material to clean. A sensitive material like thermo labile polymers is as possible to clean as metal, glass and ceramics. But the plasma system has to be adapted to the specific task. 

Depending on the gas mixture the plasma environment becomes oxidative or reductive. Oxidative plasmas are advantageous against organic impurities, i.e. oil and grease, while reductive plasmas remove inorganic deposits like metal oxides.Often for further treatment, i.e. paint work, finishing, application of hard coatings, etc., the work pieces have to be cleaned.

Plasma cleaning has proved to be the best way to get really clean, absolute grease-free surfaces. 

Classical cleaning methods often utilize wet bath chemistry with hydrocarbons (HC), chlorinated hydrocarbons (CHC) or aqueous detergent solutions. All of them cause environmental problems especially its disposal. Pollution control is done by end-of-pipe techniques, like scrubbing or filtering, etc. Compared to wet bath chemistry, plasma cleaning is much better and fulfills the much sought after environmental protection.To understand how the plasma cleaning works, lets look at it on a microscopic scale, and what happens on and in the vicinity of the surface being treated. 

In the case of organic contaminants the plasma gas will contain oxygen and argon.

The cleaning effect is the sum of at least two processes, a physical and a chemical one:

• Physical: if the work piece is conductive it will be connected like a cathode (negative electrode). Then positive ions are accelerated towards the work piece by an electric field. They hit the surface and transfer their momentum onto it. Thus molecules and atoms are removed. These events are comparable to billiard with ions.
• Chemical: 
Activated oxygen, oxygen atoms and their ions react with hydrocarbons to form carbon dioxide and water. If the reaction is complete, it gets the following form :
 Hydrocarbons are converted into comparably harmless gaseous compounds. Remaining products of any incomplete combustion, if there are any, can be easily removed from the exhaust gases by activated carbon. Further filtering is not necessary.

Therefore, plasma cleaning is indeed an ecologically clean process. 

Plasma cleaning offers some remarkable advantages in process, economy, ecology, and last but not least safety at the work environment.

Process
• high degree of degreasing
• good fissure or groove cleaning capability
• in situ readiness for further plasma treatment, i.e. coating
• high stability
• easy control
• applicable to sensitive, thermo-labile materials

Economy
• low costs of disposal
• no need for drying
• low consumption of plasma gases

Ecology
• solvent free
• no critical waste
• minimum disposal
• integrated environmental protection

Working Safety
• only little efforts necessary for storing the compressed gases oxygen and argon