Each and every spray systems is made up of three crucial parts: a compressor to pressurize the paint, a container to hold the material and a spray gun to spread it across the required surface through its nozzle in a fine mist. The process of painting by use of compressed spray gun is very simple. On pressing the trigger switch, Ventury effect gets formed, and the paint combines with the compressed air releases itself into the surface as a fine mist.
Different spray painting techniques are employed to paint the surface of a car and all of them use compressed air or fluid or air pressure to discharge and direct the spray. Spray guns are commonly used for spraying cars. Spray guns have two main classifications: suction fed and gravity fed. Both are easily identifiable from its shape and the way it is arranged.
In suction fed spray guns, the paint container is fixed below the air gun and compressed air is used to attain the desired spread. It also has a dedicated air cap to generate low vacuum. In gravity fed, the container is at the top of the gun and the major force acting on the system is gravity though compressed air is used to a lesser extent. Gravity fed spray guns are capable of giving good performance than suction fed guns, as it uses less compressed air and has less weight.
Another process is the HVLP or High Volume Low Pressure system. Though akin to spray guns as far as the compressed air is concerned, the gun works at low pressure. The effect is that wastage is minimized to a large extent.
High Volume Low Pressure technology is used by professional refinishers and painting contractors. HVLP technology is where the turbine motor feeds a high volume of air through a spray gun at very low pressure. This gently forces the paint out of the gun and atmoizes the paint at the nozzle rather than blast it out like an airless. The continual airflow through the aircap acts likes a jacket or force field keeping the spray confined. This gives you greater control of the spray and makes it much easier to achieve a high quality finish with very little experience or skill.
A third process uses Low Volume Low Pressure or LVLP system, and is an improvement of the HVLP system of painting. Here wastage is further controlled and the intended surface gets more paint. Both HVLP and LVLP system need high capacity compressors and may not be ideal for every day use.
In Electrostatic Spray painting, paint powder is used in this technique. When the paint is discharged from the gun, it is so arranged that it develops an electrostatic charge and is sprayed to the oppositely charged surface. As the minute paint particles repulse each other, the area covered by the paint is much more than other systems.
It is important to adhere to safety norms as fine mists of paint are formed and gets released into the air.