CO2 blasting and automatic brush cleaning at the expense of higher energy costs. Quality requirements A standardisation of the quality requirements for cleaned surfaces regarding the following process (e.g. coating, heat treatment) or from the point of view of technical functionality is difficult. However, it is possible to use general classifications. In Germany, it was attempted to define cleaning as a subcategory of metal treatment (DIN 8592: Cleaning as sub category of cutting processes), but this does not cope with all the complexities of cleaning. The rather general rules include the classification in intermediate cleaning, final cleaning, precision cleaning and critical cleaning (s. table), in practice seen only as a general guideline. (1) Related to the total dirt; (2) Only related to carbon Thus, the rule of thumb is still followed, stating that the quality requirements are met if the subsequent process (see below) does not cause any problems. For example, a paint coating does not flake off before the guarantee period ends. Where this is not sufficient, especially in case of external orders, because of missing standards, there are often specific customer requirements regarding remaining contamination, corrosion protection, spots and gloss level, etc. Measuring methods to ensure quality therefore do not play a bigger role in the workshops, although there are a broad scale of different methods, from visual control over simple testing methods (water break test, wipe test, measurement of contact angle, test inks, tape test, among others) to complex analysis methods (gravimetric test, particle counting, infrared spectroscopy, glow discharge spectroscopy, energy dispersive X-ray analysis, scanning electron microscopy and electrochemical methods, among others). There are only a few methods, which can be applied directly in the line and which offer reproducible and comparable results. It was not until recently that bigger advancements in this area have been made The general situation has changed, meanwhile, because of dramatically rising cleanliness requirements for certain components in the automotive industry. For example, brake systems and fuel-injection systems need to be fitted with increasingly smaller diameters and they have to withstand increasingly higher pressures. Therefore, a very minor particle contamination may lead to big problems. Because of the rising innovation speed, the industry cannot afford to identify possible failures at a relatively late stage. Therefore, the standard VDA 19/ISO 16232 'Road Vehicles – Cleanliness of Components of Fluid Circuits' was developed which describes methods that can control the compliance with the cleanliness