AIRLESS PAINT SPRAYING
An airless paint spraying system has a pump that forces paint up a hose and out of a spray gun through a very small tip. The nozzle on the end of the spray gun creates a fan pattern of paint onto a surface. Spray gun tip size, as well as the pressure level, dictates the rate of paint flow.
Advantages of Airless Paint spraying:
- The coating penetrates better into pits and crevices.
- A uniform thick coating is produced, reducing the number of coats required.
- A very ‘wet’ coating is applied, resulting in good adhesion making the coating is less likely to fail and more likely to last for a long time.
- Airless spray units are ideal for onsite paint spraying because they can be transported easily. The motors are not too heavy as they are usually less than 1 hp.
- This technique is very versatile in that it can be used in interiors and exteriors on a variety of different types of projects ranging from roller shutter doors to huge expanses of metal clad roofs.
- If you want to re-coat the surface quickly, airless spraying is the method to choose. Paint can be applied up to four times as quickly as with a brush and twice as fast as a roller. This can save up to 75% of labour time.
- As the airless technique covers large surface areas quickly, project managers don’t have to wait for long periods of good weather to schedule in exterior projects such as painting roofs.
- The liquid flows out from the gun quickly and easily meaning it lays paint on a surface evenly, unlike brushes or rollers, which leave ridges in the coating.
- The coating is thick, so not as many coats are needed as in other methods.
- It gives a flawless finish.
- Any type of liquid can be applied using an airless gun, unlike the electrostatic method which doesn’t suit water based paints or paints containing metallic particles.
Most coatings can be sprayed with very little thinner added, thereby reducing drying time and decreasing the release of solvent into the environment.
Paint can be applied up to four times as quickly as with a brush and twice as fast as a roller. This can save up to 75% of labour time.
How does Airless Spraying work?
It is viscosity and surface tension that hold liquids together and atomisation dissipates these to produce a mist of droplets instead of a continuous mass of fluid. In airless spray painting systems the energy produced by the high pressure, that is injected into the paint, is strong enough to achieve atomisation.
The paint is pushed through a hose then out of a minute hole in the tip of a spray gun where it exits in a continuous stream under extremely high pressure. However, when it comes into contact with the air it breaks up into a spray of extremely small droplets.
It is the size of the orifice in the spray nozzle that determines the amount of liquid that exits the gun as well as the fan-shaped spray pattern. There are a range of tips to control the atomization resulting in different spray patterns and sizes.