FAQ

FAQ

Here, we will answer basic frequently-asked questions mainly covering Lumina automatic spray guns. For specific or technical questions, or for questions about other products, please contact us via the Contact page.
(For customers wishing to select a spray gun model, the spray gun selection form can also be found on the Contact page.)

What applications can Lumina automatic spray guns be used for?

Lumina automatic spray guns can be used for a wide variety of applications as long as it involves applying a fluid on a specific target area. The most common applications are for applying release agents to dies, or stamping lubricant to press sheet metals, or for painting and coating. Our products have found success in a wide range of applications from applying adhesives or semiconductor fluxes to coating food products with melted chocolate or butter. The core function of a spray gun is to coat a specific area with thin layer of fluid using compressed air.

I am considering using a spray gun, but I do not know how to select a model.

The most important step in deciding a spray gun model is determining the type of fluid that will be used. For oil, paint, water, and alcohol, one can use a standard brass or aluminum spray gun, but stainless steel or polyphenylene sulfide (PPS) resin is necessary when using corrosive fluids. For high-viscosity fluids or fluids with solid substances, the selection becomes more limited.

The selection can be narrowed down further according to three basic elements. The first is spray pattern. The spray pattern, or shape of the spray, can include round, flat-fan, wide round, wide flat-fan, and small round patterns. The pattern should be matched to the size and shape of the object to be applied to. The second item is the number of air inlets. Lumina automatic spray guns include single-inlet models and models with two or three inlets. Single-inlet models (such as the ST-5 and HM-1) do not allow for the particle size or force of the spray to be adjusted. For applications in which it is desirable to avoid overspraying or to be able to finely adjust the force of the spray, we recommend models with two air inlets (such as the ST-6 and HM-6). (For details, see the section entitled “What is the difference between the ST-5 and ST-6 or the HM-1/HM-3 and HM-6?”) Once you have determined a spray gun type, the last thing to decide is nozzle size. The ST series is compatible with four nozzle sizes ranging from 0.5 mm to 2.0 mm. Please select a nozzle size depending on fluid viscosity and spray volume. (Also, please read the section below entitled “Concerning spray gun selection.” For consultations involving spray gun selection, please contact us via the Contact page.)

What is the difference between the ST-5 and ST-6 or the HM-1/HM-3 and HM-6?

The ST-5, HM-1, and HM-3 have one air inlet, while the ST-6 and HM-6 have two. Automatic spray guns use compressors to turn them on and off and to atomize a fluid. For models with single air inlet, the pipe supplies air for both of these functions. These models need an air pressure of 0.3 MPa or above (depending on the variety of spray gun) to turn the spray on and off, so high air pressure is naturally required for atomization. This causes the mist to be made finer, which results in overspraying. To prevent this, the ST-6 and HM-6 are equipped with two separate air inlets. With two air pipes, not only is it possible to provide a soft mist, it is also possible to provide a powerful spray similar to models with only one inlet. For customers who cannot decide between the two types, we suggest a model that has two air inlets. (For information concerning the basic structure of a spray gun, please refer to the “Simple Guide to Spray Gun Operation.”)

What is the difference between the models that have an X at the end of the model name and the ones that do not?

Models without an X at the end of the model name have fittings (hose joints and nipples) that act as inlets for fluid and air (see the left side of the image). When using tube fittings (one-touch fittings) – which are currently the standard – these fittings are not necessary, so please select a model that has an X on the end.

joint and nipple
What do I need in order to use a spray gun?

Please check the “Necessary items” section in the Simple Guide to Spray Gun Operation.

Do spray guns require maintenance?

Yes, spray guns require periodic washing to perform in a stable manner. The frequency of maintenance varies with the viscosity of the fluid used and the usage environment. Spray guns used with most adhesives and paints require more detailed maintenance, but when using lubricants and the like, they do not require as much. For disassembly, washing, and greasing instructions, please see the “Maintenance Manual” in the Downloads section.

How are spray guns operated?

Spray guns are turned on and off by compressed air. When compressed air (piston-actuated air) at a pressure of 0.3 MPa and above (and it depends on the model) enters a spray gun, a valve inside the spray gun (a piston set on the ST series and a piston valve on the HM series) opens, allowing fluid to pass. When the air flow is stopped, the valve closes and the fluid is stopped. Accordingly, when the spray gun is operated with automated controls, an input signal is sent to the control box or solenoid valve to determine the timing that air is let through, turning the spray gun on and off. (For instructions on how to connect spray guns and for information on their basic structure, please refer to the “Simple Guide to Spray Gun Operation.”)

Don’t spray guns overspray?

Whether a spray gun oversprays or not is determined by the force with which air is fed and particle size. By setting the atomizing air pressure low (for low-viscosity fluids, a low setting would be around 0.02 to 0.05 MPa), the particle size grows and the force of the spray is weaker, preventing overspraying to the surrounding area and allowing for a soft coating of the target object.

Can the fluid be provided using a suction mechanism?

For spray gun models that atomize the fluid inside of the air cap and mix internally, the strong force of the air feed does provide some suction on the fluid, but this method does not always provide a stable feed. Spray gun models that mix externally such as the ST-6 have no suction mechanism. As a general rule, when using a gravity feed receptacle to provide fluid, make sure to set the fluid level higher than the spray gun.

Where can I purchase Lumina products? Can I purchase them directly?

For estimates and orders, please contact your country’s authorized dealer. Many Lumina products found on e-commerce sites are fake, particularly those listed on Asian sites. When purchasing our products, please take care to purchase from legitimate dealers. For countries without authorized dealers, please contact us directly on the Contact page.

I found a product identical to yours for sale online. Is it an authentic Lumina spray gun?

Fake Lumina spray guns are prevalent on electronic commerce sites, particularly ones based in Asian markets. Any product that does not have the Lumina logo engraved on the body or does not include a “Pure Japan Made” card in the package is not an authentic Lumina product (even products that include the engraving or card may be fake). Authentic Lumina automatic spray guns distributed by one of our authorized overseas dealers include a holographic sticker bearing the serial number (not including air brushes and other accessories). Products that do not fit the above description may be fake. Our company cannot guarantee the quality of such products and they do not qualify for follow-up services.

Concerning model selection

The following notes concerning model selection are meant to be general guidelines. The ideal model for your needs may vary depending on factors other than those listed. For customers who have specific uses in mind, please contact us through the Contact page.

Which spray gun should I use for solvent-based fluids?

The ST series and the MK-3 feature solvent-resistant packing and can be used to spray organic solvents. Models from the HM series, the PR-40X, and the MS series do not feature solvent-resistant packing and cannot be used. However, for these models, we accept special orders for custom models that feature solvent-resistant packing. Please contact us for such orders.

Which spray guns can be used for strong acids or other caustic fluids?

Standard models from the ST series and HM series have brass bodies with chrome plating which may corrode depending on the fluid used. For such fluids, please use one of the models with stainless steel bodies (such as the STS and STA from the ST series). For spraying highly acidic chemicals that will ruin even stainless steel, please use an HMP model, which have polyphenylene sulfide (PPS) resin bodies.

Which spray guns can be used for food products?

When using spray guns for creating food products, we recommend stainless steel models such as the STS series. Standard models undergo exterior plating treatment, so there is a non-zero risk of the plating chipping off and contaminating the food product. Also, our products feature valves that are greased to ensure they slide smoothly. That grease can be replaced with food grade grease. Please ask us about this when requesting an estimate.

Which spray guns can be used with high viscosity fluids such as adhesive glues and drawing oils?

The MS series and PR-40X accept a maximum nozzle size of 3.0 millimeters and can be used to coat with high-viscosity fluids. With its wide passageway and spiraled nozzle tip, the MS series is the most clog-resistant model out of Lumina’s entire product lineup. Also, the ST-6RW uses the same spiral nozzle and there are many cases in which it has been successfully used for applying adhesives and similar fluids.

Which spray guns are suitable for applying minuscule amounts of fluid?

For applying minuscule amounts of fluid, we recommend small round type models with fine-tuning capabilities such as the ST-6SK-0.5X-MHS and the ST-10SK-0.5X-MHS. They enable the user to easily confirm fluid amounts visually with scaled micrometers that have thimbles with 50 graduations per rotation and graduation lines.

Which models apply coating without spraying mist?

The ST-6PR is a model for applying lubrication to a single point by applying a stream of fluid instead of a mist (pressure must be applied to the fluid). Models with two air inlets such as the ST-6R and HM-6R can also provide non-mist fluid output by feeding them just piston-actuated air (CYL). As for drip lubricator systems, we have the Oil Snake and the Tap Touch.

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