The 2 litre pressure cup & pressure gun combo has quite a few benefits over a gravity or siphon cup gun:
1). Twice the capacity, so half the time spent refilling with paint.
2). Up to kg less weight in the spraying hand, so less fatigue and no aching wrist.
3), Without a cup on the gun, it means you can get into small cupboards without the cup hitting the frame work.
4). Pressure cups allow thicker paints to be sprayed.
Pressure guns can generally atomise thicker paints as the compressed air coming out of the air nozzle is devoted purely to atomisation. Where as siphon and gravity guns devote some of the air to create a vacuum to pull the paint through.
5). Hold the pressure cup in your non spraying hand or hang off your belt.
6). The pressure gun will give up to an 8″ (200mm) fan pattern
1). Safety point. Always make sure the pressure cup is depressurised before unscrewing the cup.
2). When setting up a pressure gun, a good rule of thumb for setting the pot pressure is to turn off the gun atomising air. With paint in the pressure cup, increase the pot pressure incrementally until when you pull the gun trigger you get a stream of paint horizontal for about 5 to 6 inches, which then starts to drop. If after doing this, and you do not have enough paint coming out of the gun when you spray, then you need to go up a fluid nozzle/needle size or two. The 5 to 6 inch rule is such that if you have the cup pressure to high then the velocity of the paint as it comes out of the front of the gun is too high, and too fast for the gun to satisfactory atomise the paint.
3). Fluid nozzle selection. Generally the thicker the paint, then like airless you need a bigger nozzle. Nozzle sizes range from 1.1 mm (solvent based paints and lacquers) to 2.2mm (non thinned water based primers). 1.8 mm fluid nozzle and above needs the bigger air cap/nozzle. 1.1 to 1.5 mm fluid nozzles use the same air cap.
4). If using a variety of different primer and top coat paints then it is best to have a selection of the fluid nozzle and air nozzle combinations. Just like with airless or AAA you have different size tips for different paints.
5). With the Iwata (and all spray guns) always keep the air pressure as low as possible. Start with low pressure then increase until you get a good finish. The more air pressure the lower the transfer efficiency (wastes more paint).
6). Horses for courses. Compressed air Conventional, LVLP or Compliant guns have a greater range of paints that they can atomise over HVLP turbine systems. It is because they can go above the legal HVLP air pressure limit of 10 psi (0.7 bar) at the gun air nozzle. But because they can, it means the transfer efficiency will go down as the air pressure goes up. So as point 5, keep it as low as possible.