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The fan pattern refers to the shape and coverage area of the spray that comes out of the nozzle when you trigger the spray gun. It is also called the spray pattern.  

An uneven fan pattern will result in uneven coating thickness, dark stripes, light spots, and rough texture in the painted surface. We'll walk through the steps for properly inspecting and adjusting your air spray gun's fan pattern.

1. Choose an Appropriate Test Surface

It's important to test your spray pattern on a suitable surface. Avoid testing on your actual workpiece. Good test surfaces include cardboard, wood panels, and poster board. The test surface should be large enough to fully visualize the entire fan pattern. Darker colored surfaces also make it easier to see the pattern.

2. Set Up the Test Area

The test area should be well-ventilated and lit. It should be free of overspray or debris that could distort the pattern test. Position the test surface vertically, and make sure you have adequate room to stand back and examine the entire spray pattern.

3. Adjust Nozzle and Air Pressure

Generally, a smaller nozzle paired with lower air pressure produces a narrower fan pattern. A larger nozzle and higher pressure creates a wider pattern.

4. Apply a Test Spray Pattern

Hold the spray gun perpendicular to the test surface, at the appropriate spray distance. Make a quick pass across the surface, being sure to start spraying before the surface and stop spraying after. This will reveal the full size and shape of the pattern.

5. Examine the Pattern

Step back and carefully analyze the entire spray pattern. An ideal fan pattern should be symmetrical, with soft, feathered edges. It should evenly distribute paint across the full width of the pattern.

6. Make Adjustments

Based on what you observed in the pattern, make small adjustments to the nozzle size, air pressure, or paint flow. Test again to see the results of your adjustments. You may need several rounds of testing and tweaking to achieve an optimal fan pattern.

Troubleshooting Uneven Patterns

Here are some common causes of uneven fan patterns and solutions:

Problem: Heavy coating in the middle, light on the edges

Solution: Increase air pressure or move spray gun closer to the surface

Problem: Dark stripes or bands across the fan pattern

Solution: Clean air cap slots, ensure nozzle/needle seated properly

Problem: One side heavier than the other

Solution: Adjust spray angle so gun is perpendicular to surface

Problem: Excessive overspray, fuzzy edges

Solution: Reduce airflow pressure, verify proper nozzle size

FAQs About Spray Gun Fan Patterns

Checking and adjusting your spray gun's fan pattern is crucial, but many first-time spray gun users have questions about this process.

How do I know if my spray pattern is good or bad?

A good fan pattern will be symmetrical, with soft edges and even distribution of paint across the full width. A bad pattern may have uneven edges, heavy spots in the center or sides, or an irregular shape.

What causes a distorted spray pattern?

Common causes are dried paint clogging the nozzle, improper nozzle/cap setup, debris in the gun, too much or too little paint or air pressure, or defective parts.

How wide should my spray pattern be?

The ideal pattern width depends on the size of the object you're painting. For broad surfaces, a 10-12 inch pattern is common. For narrower surfaces, a 6 inch pattern works better.

How do I fix paint tails or fingering at the edges?

Paint tails indicate the paint air pressure needs to be reduced. Try lowering the pressure until the edges fully atomize and become soft.

Should I test the pattern with paint or just air?

Always test with paint or water, as the spray pattern characteristics will look different with paint versus air alone. Test with consistent paint viscosity and with the air cap installed.

What should I do if one side of the pattern looks different?

This likely indicates a problem with a clogged or defective nozzle or air cap. Try cleaning the nozzle first. If the issue persists, replace nozzle and cap parts.

The RONGPENG R804 HVLP Spray Gun brings professional-grade spraying power to everyone from DIY home painters to body shops.

Aluminum alloy gun body with anodic treatment surface. Air micrometer with graduations to adjust atomization air. Spray gun body designed with small dimensions and low weight for fatigue-free working. Single-handed flat control to adjust the spray pattern to the object which is to be painted.

Best used for vehicles, furniture, instrumentation, mechanical equipment, spraying operation, suitable for water soluble paint spraying.

Model No:R804

Standard Nozzle:φ1.3mm

Operating Pressure:2.4-3.0bar

Pattern Width:200-300mm

Air Consumption:5.5cfm

Paint Capacity:400cc

RONGPENG has quickly risen to become an unrivaled global producer of air-powered devices including air tools, air spray gun, air nailer, airless paint sprayer, and etc.

RONGPENG seeks independent sales agent to represent and market our industry-leading pneumatic tools. We support OEM, ODM, OBM customization, small order quantity is acceptable and samples are available.

Make any cooperation possible. Any services related to the product, inquire with us now!   Rongpeng@Rongpeng.Com