Spray Gun Tip Size

 Spray Gun Tip Size. A Guide for Professional Painters

To get results, high transfer efficiency and minimal defects you need to understand more about spray gun tip size. The tip size is not a number it controls the flow rate, how the paint is broken up the fan shape and how the paint behaves on the surface.

1. The Parts of a Spray Tip

A airless spray tip like the 517 has three main parts:

A. Fan Width

This is the width of the paint fan. It is measured by multiplying the digit of the tip size by 

2. This controls how area you can cover.

For example the 517 tip gives you a 10-inch fan. The 211 tip gives you a 4-inch fan.
If you have a fan you can cover more area faster but you have less control. If you have a fan you have more control but it takes longer to cover the area.

B. Orifice Size

This is the important part. It is measured in thousandths of an inch. It determines how much paint flows through the tip.
For example the 0.017 inch orifice on the 517 tip lets paint flow through than the 0.011 inch orifice on the 311 tip.
If you have an orifice you get more paint and a thicker coat. If you have an orifice you get a smoother finish.

C. Tip Angle and Internal Shape

Newer tips like the RAC, HEA and FFLP types are designed to reduce turbulence break up the paint better at pressure and last longer.

2. How Flow Rate Relates to Tip Size

Each tip size is meant for a flow rate at a given pressure.
For example at 2000 PSI the 311 tip gives about 0.6 liters per minute which's good for a fine finish. The 415 tip gives about 1.4 liters per minute which's good for general coating. The 517 tip gives about 2.2 liters per minute which's good for painting walls and other large areas. The 521 tip gives about 2.6 liters per minute which's good for heavy coatings.
You need to make sure your pump can give paint than the tip needs or you will get uneven edges, low pressure and poor paint breakup.

3. How Tip Size Affects the Paint Finish

The paint breakup depends on the pressure, tip size and how thick the paint is.
If you use a tip and high pressure you get small droplets and a smooth finish. If you use a tip and low pressure you get big droplets and a rough finish.
You need to find a balance. If the droplets are too small you get overspray and dry spots. If the droplets are too big you get runs and poor leveling.

4. Choosing the Right Tip for the Job

A. Thin Coatings

For coatings like stains and lacquers you need a small tip, like 0.009 to 0.013 inches and low to medium pressure. This gives you a breakup and a smooth finish.

B. Medium Coatings

For coatings like enamel and alkyds you need a tip that is 0.015 to 0.019 inches. This gives you a finish and good productivity.

C. Heavy Coatings

For coatings like epoxy and elastomeric you need a larger tip, like 0.021 to 0.025 inches or more. You also need a pump that can handle a lot of paint.

5. Common Problems with the Spray Pattern

1. Tailing

This happens when the tip is too big for the pump or the pressure is too low. To fix it you can increase the pressure. Use a smaller tip.

2. Runs and Sagging

This happens when the tip is big and too much paint is flowing. To fix it you can use a tip or move the gun faster.

3. Dry Spray or Rough Finish

This happens when the tip is too small or the pressure is too high. To fix it you can use a tip or lower the pressure.

6. Tip Wear

The tip can wear out because of pigments or high pressure. When this happens the orifice gets bigger. The paint flow increases. The fan pattern also gets uneven.
You should replace the tip when the flow increases by 10 to 15 percent or the fan loses its shape.

7. Finding the Right Pressure

of guessing you should start with low pressure and increase it gradually. You should stop when the fan is even and there is no tailing.
This is called the Minimum Effective Pressure. It helps reduce overspray makes the tip last longer and gives you results.

8. Matching the Tip to the Pump

Every airless sprayer has a flow rate and a maximum tip size.
For example a small pump can handle a tip up to 0.017 inches. A medium pump can handle a tip up to 0.021 inches. A heavy-duty pump can handle a tip of 0.025 inches or more.
If you use a tip that's too big for the pump you can damage the pump and get a poor finish.

9. Advanced Tips

You should use tips, like the RAC because they are easy to clean and reduce downtime. You should also use low-pressure tips, like the HEA and FFLP because they give you control and less overspray.
You should always carry tips, including a fine finish tip, a medium tip and a heavy coating tip. You should also control the distance and speed of the gun to match the flow rate.

10. Real-Life Examples

Example 1: Painting a Steel Structure with Epoxy Primer
You would use a 521 tip and high pressure to get a coat.

Example 2: Painting Furniture
You would use a 311 tip and low pressure to get a finish.

Example 3: Painting an Interior Wall
You would use a 517 tip and medium pressure to get coverage and productivity.

Final Thoughts
Choosing the spray gun tip size is about finding a balance, between four things: the tip size, the pressure, the paint viscosity and the pump capacity. If you master this you can become a painter.