Thanks to its many advantages, such as speed and ease of use, the use of an Airless sprayer for applying compounds has become widespread among building professionals, both painters and multi-service contractors. But to achieve the quality finish expected from this method of application, it is essential to master the equipment and the appropriate techniques.
Equipment for Airless compound application
“Airless,” literally “without air,” refers to a method of spray application that projects paint or compound onto a surface evenly and consistently, without using compressed air. Initially designed for paint, the Airless machine has since been adapted for compounds and can therefore also be used to coat all types of surfaces prior to painting.
The Airless sprayer – or Airless gun – is the key tool in this method. It works by pumping the compound at high pressure through a special nozzle, creating a fine spray that adheres automatically to the surface. According to technical guides, a pump brings the coating material to very high pressure. When the gun is opened the material is forced through the tip, and atomisation is created by the pressure difference between the material and the atmosphere.
There are different types of sprayers, such as electric and pneumatic models. The choice depends on the type of project and the desired portability. The pressure and nozzle size must be matched to the compound being used and to the surface to be treated.
Nozzles and tips are also important because they determine the spray width and the angle of dispersion. For best results, it is advisable to select the tip size according to the density of the compound and the size of the surface to be coated.
Last but not least: protection. Although Airless application is much faster than manual application, it does require more preparation – in particular, protecting the area to be coated before starting the spray. This is necessary to avoid splashes and to work in good conditions.
You will also need the proper equipment to prepare the surface – cleaning it, sanding it if necessary and filling holes when there are major irregularities – and to carry out the finish. For the latter step, a trowel or smoothing blade is required. Even when the application is mechanised, the smoothing is done by hand.
Which technique should you use?
Once the surface has been prepared, the professional can move on to Airless application. First, the compound must be prepared to the ideal consistency for both an even spray and the type of surface to be coated. The product is then loaded into the machine and ready to be sprayed.
If the professional is working alone, they should work area by area: spray the compound, then smooth it out before the surface dries, and repeat this until the entire area is coated. If a colleague is assisting, continuous spraying is possible while the colleague takes care of the smoothing.
After the first pass, you should allow 24 hours’ drying time before applying a second coat.
Airless compound application can be used for all types of renovation projects, but it is particularly well suited to large volumes. It is therefore often used on sites involving the renovation of entire houses or buildings.
Tips and pitfalls to avoid
Using an Airless sprayer represents a certain investment for the professional, since buying a machine costs between €5,000 and €10,000 on average. However, the return on investment is rapid thanks to the productivity gains this method provides.
Nevertheless, everything depends on whether the machine is used properly. Cleaning it, for example, can put some people off, and there are professionals who leave the machine in the cupboard rather than having to clean it regularly.
Cleaning is fundamental to the proper functioning of an Airless sprayer and to its long-term maintenance. The tips and nozzles, in particular, must be washed after every use to avoid blockages. They are very fine, since the spray at the gun outlet is measured in millimetres. For the same reason, it is inadvisable to put leftover sprayed compound back into the bucket for spraying: a few dust particles in the mix are enough to damage the nozzle and cause the spray to deflect or, worse, become completely blocked.
Fortunately, cleaning the machine is actually much quicker than it appears. Experts have timed themselves: it takes nine minutes, stopwatch in hand, to clean all the parts. When you compare this with the time saved on site, it is well worth the effort. Of course, you need the right technique, and training courses are available for this.
Finally, not all Airless machines are suitable for spraying compounds. Some are designed only for paint. To apply compound with an Airless sprayer, you need a machine with a flow rate of at least five litres per minute.