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A selection of paint gun nozzles and tips
Auto Paints & Painting Equipment Technical

Choosing the Right Fluid Tip, Needle, and Cap for Your Paint Gun

Mastering the art of painting a car goes beyond just selecting the right paint. It also requires an understanding of the equipment, particularly the spray gun itself. A common question new painters ask is what size fluid tip, needle, and nozzle they need for their specific job. These three components determine how the paint atomizes, at what rate it flows, and what the spray pattern looks like. And because different automotive paints have unique viscosities, each type requires a different size for proper application. Let’s dive into why these variations matter, how they affect results, and tips (pun unintended) for choosing the right setup.

Fluid Tip Sizes Explained

The fluid tip, needle, and nozzle (or air cap) are the three atomizing components of a typical HVLP spray gun. The dimensions for these components refer specifically to the diameter of the hole in the center of the fluid tip. Typically measured in millimeters (or sometimes inches), this ranges from about 1.0 mm to 2.5 mm for most paint guns. The nozzle covers the tip externally (responsible for controlling the direction of the fan pattern) and has a corresponding diameter. The needle, which controls airflow, has a larger diameter than the tip but is tapered to match its internal profile.

 

 

Exploded view of an Eastwood Concours Pro paint gun
The anatomy of an Eastwood Concours Pro paint gun

Many paint guns are sold with a single tip installed, however most general-purpose guns can be swapped out with tips of other sizes. Eastwood’s Concours Pro paint gun, for instance, is equipped with a 1.3 mm tip, but offers optional 1.7 mm and 2.0 mm tips. Other guns are designed to more job-specific, offering only one tip size. These include dedicated primer guns with large tips and detail guns with fine tip.

Affects of Fluid Tip Size

The tip size affects several key factors that impact the results of your paint job. These include what type of paint you can spray, the spray pattern, flow rate, atomization, and distance from the surface. Its size determines the maximum viscosity of the paint or coating that can be effectively atomized, for instance. Simply put, thicker materials require larger tips for proper flow. A larger tip size allows for a wider spray pattern, making it suitable for larger surfaces, while a smaller tip offers a finer spray for detailed work. Size affects the flow rate of the material, influencing how much paint is applied in a given time. The tip size also impacts paint atomization, critical for achieving a smooth, even finish without runs or orange peel. Different tip sizes may also require different application techniques, including distance from the surface and speed of movement.

Closeup view of paint gun nozzle showing 1.7 mm opening
Closeup view of paint gun nozzle showing 1.7 mm opening

Common Fluid Tip Sizes for Different Paints

Each paint gun manufacturer has its own unique designs for its tips and nozzles. However, laws of physics dictate how a fluid passes through a small opening. Therefore, most HVLP spray guns will offer similar tip dimensions for a given paint type. Here are the most common tip/cap sizes for different types of automotive paints:

  • Basecoat Paint – 1.2 mm to 1.4 mm – These sizes provide a good balance between atomization and coverage for most basecoat paints.
  • Clearcoats – 1.3 mm to 1.5 mm – A slightly larger tip helps achieve a smooth finish and proper flow for clearcoats.
  • Single-Stage Paints – 1.4 mm to 1.6 mm – These sizes work well for applying single-stage paints that combine color and clear in one layer.
  • Primers – 1.5 mm to 2.0 mm – Larger tips are needed to accommodate the thicker viscosity of primers, including epoxy, urethane, and polyester.
  • Specialty Coatings  – 2.0 mm to 2.5 mm – Larger tips are necessary for thicker material like undercoating or bed liner, ensuring proper coverage and application.
  • Waterborne Paints – 1.2 mm to 1.4 mm – Similar to solvent-based paints, but may require slight adjustments based on the specific formulation. Selecting the right tip size based on the type of paint and application technique is essential for achieving optimal results.
1.7 mm tip/nozzle set shows markings on all three pieces (circled)
1.7 mm tip/nozzle set shows markings on all three pieces (circled)

Precautions

As stated above, tips, nozzles, and needles are designed as matched sets. Therefore, changing one component but not the others can lead to inconsistencies in your work. Mixing different sized needles, caps, and tips in an HVLP paint gun can lead to the following issues:

  • Inconsistent Spray Pattern – Different sizes can create uneven atomization, resulting in a spray pattern that may be too wide or too narrow, making it difficult to achieve a uniform finish.
  • Poor Paint Flow – Using a needle and tip that are mismatched can lead to insufficient paint flow or excessive flow, which can cause runs, drips, or uneven coverage.
  • Clogging – If the tip size is too small for the paint viscosity, it can lead to clogging. Conversely, too large a tip with a thin material can result in overspray and waste.
  • Finish Quality – Inconsistent atomization can result in surface defects like orange peel, streaks, or gloss variation.
  • Increased Wear and Tear – Mismatched components can put extra strain on the gun, leading to premature wear or damage to parts like the needle and tip.
3 paint gun needles showing the different taper profiles
The smallest 1.3 mm needle (top) is more tapered that the blunt 2.0 mm top (bottom) though the shaft diameter is the same for all three

 

 

5 Comments

  1. Cómo puedo saber a que presion de psi regular mí pistola de punta o boquilla 1.4 para pintura regular o carros de hoy en día

  2. hi i like this segment you talk about thermal expantion i am rebuilding an alu boat the sides and panels flex a lot would it be a help to put flex agents in the paint

  3. Enjoyed this! Now, how about an article on the balancing of fluid, fan and air with respect to most commonly used paints? Can allowances be made inn the mixing of thinners to what you are spraying?

  4. It’s good to know about tip I find out from the paint supplier with there tds sheets (technical data sheet) also the gun manufacturer tells you the amount of air needed to use the gun properly (how much cubic feet per minute is needed to use this gun). The tds sheets have all the information you need to use ther product so it comes out the best

  5. Great information! Wish I would have known this when I was younger. Thank you!