Our SELEMIX® technical experts have prepared some practical tips to help the professional painter to achieve the best spraying results when using air-assisted airless spraying equipment.

The basic principle of air-assisted airless spray is that the paint is atomized by pumping it at pressure through a narrow orifice (the tip of the gun).  

Pressures are, however, reduced as the gun has an air cap which gives a secondary atomization and breaks up and tailing that can occur.

It should not be underestimated that the spray gun is more complex than an airless gun. It has both a fluid line and an airline going into it.

Typical spray pressures for air-assisted airless spray are 800-1500 psi/ 55-100 Bar. Key benefits of spraying at a lower pressure are a greater control and a better quality of finish.

To gain the best outcome, we  recommend the following steps:

  1. Turn off the air pressure to the gun.
  2. Increase the fluid pressure until a continuous fan with distinct upper and lower tails is achieved (normally at around 800-1500 psi/ 55-100 Bar).
  3. Turn on the atomizing air pressure to the gun to eliminate the tailing (normally 15-30 psi/ 1-2 Bar).
  4. If you have trouble achieving good atomisation or getting tailing on the fan, the paint may require the addition of thinner. Refer to the Technical Data Sheet (TDS).
  5. For the correct tip size, make sure you follow the TDS instructions. As a thumb rule, for Selemix topcoats you would use a tip size of 9-11 thou. For Selemix primers it would be 11-15 thou.
  6. The tip angle (determining the angle of the fan) should reflect the object being painted.As a general recommendation, for large flat surfaces, use a larger angle and for smaller surfaces, use a smaller angle.

For the best results we recommend all painters that you should spray from a greater distance, when compared to conventional spraying. We suggest a  distance of approximately 50cm. In addition, in between passes you should not turn your trigger off as this will lead to fouling at the tip of the spray gun.

Following these simple practices should help the professional painter achieve very good results when using Selemix products with air-assisted airless spraying equipment.