Error in the spray pattern
Irregularities and defects in paint application. A spray pattern changes due to various parameters. However, an error in the paint jet is attributed to the spray gun.
Fig.1: Spray pattern depending on the design.
- the more common spray pattern is an O-shape (oval).
- spray pattern elongated l- or I-shape (elongated, straight trimmed).
- wet core in the spray pattern.
- dry edge overspray spray pattern outside.
- I-shape is visibly easier to control. The oval shape applies more material to the wet core.
Fig. 2 A: Spray pattern as it should be.
- elongated spray pattern and 2. an oval spray pattern.
Fig. 2 B: Sickle curvature can be caused by clogged holes.
Fig. 3 C: The core is compressed in the center. Pressure is too high, the material is too thin or holes are clogged.
Fig. 3 D: Droplet formation in the spray jet: Bore clogged or damaged.
- Recognition characteristics:
- The spray pattern of the spray jet has optical changes.
- Fluttering / pulsing of the spray jet
- The ink nozzle is not tightened properly.
- The air distribution ring is damaged or not seated correctly.
- Blockage in the gun body.
- Drop formation in the spray pattern
- Too little spray pressure.
- Air supply interrupted (hose disconnected from line, hose kinked, or something is preventing air passage, like someone or something standing on the hose).
- Drip formation on the air cap due to contamination or clogging at the air guide holes.
- For spray cans, too little pressure in the can or the spray head does not work properly.
- The air cap is not fully tightened.
- Spitting paint pigments
- Detachment of paint residues on the air cap or „horns“.
- Ink accumulation at the ink nozzle tip.
- Too little spray pressure.
- Possibility of a defective pigment in the mixed color.
- The material was not sieved before processing.
- Sickle curvature in the spray pattern
- The holes on the air cap are dirty or damaged.
- The paint nozzle is dirty or damaged.
- Streaking in the coating
- Check the air pressure or spraying pressure.
- The material viscosity is set too low. The material is too thin.
- The nozzle size is too large for material viscosity.
- Holes on the air cap are dirty or damaged.
- Incorrect angle of the gun to the object. Check the painting technique.
- The amount of material decreases during spraying
- The air intake hole in the tumbler lid clogged. The tumbler draws a vacuum.
- The stopper on the bucket system is not opened.
It is generally recommended to check the spray pattern before applying the material. Tip: Use a large sheet of masking paper on the booth wall or a spray pattern test stand designed for this purpose. To do this, set the spray gun to wide spray, 20 cm away from the object, and pull off once. You can now read from the crescent shape whether all the holes are in order and the spray gun is ready for use.
In the event of an error in the spray jet, one should always keep in mind that by not checking, several hours of preparatory work can be destroyed. The extent of the financial damage is just as important here. It is not only the material that is uselessly wasted but also many working hours.
Of course, you can call it „naysaying“. But it is better to invest 10 minutes more in clean preparatory work than several hours in unpaid time for rework.