I have two air compressors but research shows that the size and type of an air compressor needs to be matched to its potential uses. Research on youtube is usually aimed at English language users and those familiar with Imperial measurements. So terms like CFM (cubic feet per minute) and PSI (pounds per square inch) will be thrown about. Here in France, where I am writing this, everything is in metric, so CFM becomes Litres per Minute or Second, PSI becomes Bar. One aspect that doesn’t change is HP, at least it only changes, in French, to CV. But horse power ratings aren’t always what they seem. So, one thing I have learned is that, generally, bigger is better. Though this rule only really applies when considering applications that require large, continuous volumes of air to be delivered with little or no drop in pressure. So what are the various applications in order of increasing power and volume requirements? The tool department at Leroy Merlin came to my help the other day with this scale, though it is really focussed on the high end: 100L/min, 1.5 cv, 6L tank, suitable for inflating tyres, balls, spraying degreasers and insecticides. This would also include simple air blasting/dusting. 120L/min, 2 cv, 15-50L tank, suitable for the above plus painting small areas. Small areas would include our model projects. 150L/min, 2 cv, 50L tank, lightweight sanding tools that are likely to be run more continuously. Also air tools requiring high torque. 250L/min, 3 cv, 100L tank, painting large surfaces, including houses and vehicles 300L/min, 3cv, 150L tank, Wood and metal stripping, de-rusting, sand blasting. Some observations, First, the tank pressure may be higher than the application pressure which can be easily set on many compressors or with the addition of a “choke” in line. Having a higher pressure in the tank simply means a more continuous flow of air can be maintained at constant working pressure. Second, if portability is a requirement then a smaller compressor works just as well as long as it can keep up with the application. Some airbrush compressors do not even have a tank. However on a long “blast” the pressure may fall below the optimum level with potential poor results. Third, noise can be a problem if using the compressor in a confined space. In assessing my own needs, it would appear that I might be best served by buying a 250L/min compressor but hang on to my much smaller 100L/min unit with a 6 litre tank. The large unit would be primarily for house and car painting, not exactly what most Western Thunderers are requiring. I would be interested to learn what others’ experiences are in crossing the air compressor minefield. My mind is very much open to what others have experienced. I should add that I grew up in an environment that included a 12 booth spray shop and an electrostatic spray machine. But I was dissuaded from having any future in the business so became a geologist!