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How an airless system works, and why high pressure deserves respect
Airless spraying is one of the techniques that as a building painter can make large surfaces fast to treat with a very uniform finish. But the method works at far higher pressure than many other tools in the trade, and that pressure can be dangerous if not treated with respect.
An airless system basically consists of a pump a high-pressure hose a spray gun and a nozzle. Unlike air spraying (HVLP) where paint is atomised with air an airless pump mechanically forces paint through a very small nozzle opening at high pressure which atomises it into a fine mist without using air. This gives a more even finish with less overspray than many air-based methods.
Airless systems typically work at pressures over 150 bar and can on some systems be significantly higher. This is a level that can force paint through skin if the nozzle is directed at a hand or other body part — even through gloves or clothing. That's precisely why airless spraying is one of the tasks in the painter's trade where safety procedures are not something you can skip to save time.
Before spraying the paint must be strained to prevent nozzle clogging, and the equipment must be set with the correct nozzle size for the task. During spraying the gun is held at a constant, even distance from the surface and moved parallel to it — if you tilt the gun the coat becomes uneven. After use the equipment must be cleaned thoroughly, both for the equipment's lifespan and because dried paint in pump and hose can cause clogs and high pressure next time the equipment is started.
Airless is strongest for large, uniform surfaces — facades, ceilings and industrial surfaces — where speed and an even finish are important. For smaller, detailed work with many edges and corners, brush and roller are often still the best choice, both for control and to avoid unnecessary overspray on surrounding surfaces.