A lot of times we see statistics of how efficient various methods of spraying are, HVLP is approximately 65% efficient, airless is in the neighborhood of 30% efficient. The problem with these statistics is that it doesn’t take into consideration the underlying reason for reduced transfer efficiency, over spray. Over spray is when paint is not hitting your intended target and instead is going past the part or bouncing off the part and not adhering to your targets surface. Over spray is the key variable in determining transfer efficiency.
Typically the transfer efficiency numbers we see quoted are based on spraying a similar sized object with the various methods of spraying. It is no wonder then that transfer efficiency is significantly less with airless or conventional spray compared to HVLP or Air Assist Airless when aiming at a similar target. Airless and conventional use high amounts of pressure and therefore more paint bounces off the surface as well as misses the part completely resulting in a lot of over spray and reduced transfer efficiency. However if we take an airless or conventional spray with a large target item that requires a lot of paint and adjust the fluid tips appropriately all of a sudden we reduce over spray to practically nothing, the result is the transfer efficiency suddenly starts looking more like HVLP technology.
Controlling over spray is the key to having high transfer efficiency, it is also the reason why it is critical to appropriately match your spray equipment to your specific task. The bottom line is if you control over spray you can improve transfer efficiency and save on paint.
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