Fuji Spray Air Cap sets in an Air Cap set case

Choosing HVLP Air Caps and Accessories

Many new HVLP spray gun users may not be familiar with air cap sets and accessories, and even some experienced users might not have explored different air cap sizes beyond what came with their gun.

Manufacturers usually make an educated guess when choosing the air cap size for their product, but as a consumer, it’s a good idea to experiment with different sizes. In most cases, using a 1.0mm needle and nozzle, which sprays clear finishes like lacquer and shellac beautifully, can be a great starting point, especially if you want a fine finish.

There’s an exception for thicker paints and tinted lacquers, where you’d want an air cap in the 1.5-2.0mm range. The general rule is that:

thicker coatings require a larger air cap size.

If you aim for the lower end of the recommended range, you’ll likely achieve a finer sprayed finish.

HVLP Air Caps Sets

Air cap sets are perhaps the #1 HVLP spray gun accessory to consider, and often they’re the difference between orange peel and a blue-ribbon finish.  Remember though:

aircaps are not interchangeable between guns.

M-Model kits shown above, are different from those for T-Series or the G-XPC guns.

Air Cap Set Components
An air cap set with a needle, nozzle, and air cap collar.

Every set comes with three essential components: a needle, a nozzle, and an air cap. These components are carefully matched to ensure the best spraying performance, so when you’re switching to a different size, make sure to replace all three parts.

It’s worth noting that the collar that holds the air cap is a separate piece and can be used with any size air cap.

Exploring Different Air Cap Sets
G-XPC spray gun and air caps

The G-XPC air cap sets are color-coded to help identify them at a glance.

Beyond their stated size, such as 1.0mm or 1.4mm, they also have code designations. If you see labels like 3H or 4H, don’t let it confuse you. This is just another name for air cap size. A 3H aircap is 1.0mm, and a 4H is 1.4mm.

You might also hear air cap sets described as “tips” or “needle and nozzle sets” and these terms all describe the same parts.

Notice the larger diameter of the needle shank at the back, which is a telltale sign you have a G-XPC needle.

The M-Model gun, shown in a gravity feed configuration, comes standard with a 1.3mm air cap set. If you primarily spray clear finishes, try a 1.0mm set.

You’ll be amazed at what a nice fine finish it produces. In fact, I consider a 1.0mm air cap set the #1 must-have accessory for furniture builders and cabinet makers.

Fuji Spray Spray Guns on table

There’s quite a variety of turbine-driven HVLP spray guns on the market.

From left to right, The M-Model in gravity feed and bottom feed configurations, the G-XPC side mount gravity feed, T-75G gravity feed, and T-70 bottom feed.

Note that all of these models feature pressure assist tubes and check valves, for continuous positive pressure.

Conversion Kits
HVLP Accessories

Here’s something that might catch some users by surprise: you can easily transform any M-Model bottom feed spray gun into a gravity feed configuration!

All it takes is the optional gravity feed conversion kit. This kit includes a 400cc aluminum gravity feed cup, a U-tube assembly, a pressure tube with a check valve, and a robust metal lid with a rotating quick-release assembly.

This conversion kit could very well be the top accessory for M-Model users since it significantly enhances the versatility of your bottom-feed spray gun.

M-Model Spray Gun Accessories

In addition to the M-Model gravity conversion accessory, there’s also a 600cc right-angle cup kit available for your G-XPC.

This accessory increases the original 400cc cup by 50%, letting you spray longer on those big jobs.

The kit comes with the nylon cup and lid (with pressure tube fitting), and a 90-degree swivel fitting. This hardware makes the new cup a direct bolt-on accessory for the G-XPC model.

Explore More HVLP Accessories
HVLP Air Caps and Accessories Spray Gun

Once you use an HVLP gun with pressure assist, you’ll have a hard time going back.

The continuous positive pressure is controlled by a one-way check valve. This makes sure the pressure flows only from the gun body to the cup, and not back and forth. A pressurized cup also gives you more flexibility with the angle you spray.

In fact, a pressure-assisted gravity feed gun will spray at almost any common finishing angle.

If you truly need to spray with the gun inverted for extended periods, consider the 2Qt. pressure pot accessory.

HVLP air caps and accessories

Rounding out the list of HVLP gun accessories is a Ford viscosity cup.

Simply dip the cup into your coating and start a stopwatch. The time it takes to drain is an indication of the fluid thickness. This, in turn, tells you how much to thin the fluid before spraying.

For quick reference, you can check this guide for runout times of common products.



Willie Sandry is a Freelance Writer for several woodworking magazines, professional tool tester, and spraying enthusiast. Find his latest projects and reviews on his YouTube channel at The Thoughtful Woodworker!

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