Box-Fed Vs. Hopper-Fed Powder Coating Guns

The Powder Coating Process | Products Finishing

Powder coating is a quick way to get a durable, corrosion-resistant finish on metal products. It can be used for either aesthetics or function – for example, powder coated bumpers are both highly durable and protect the vehicle’s paint from being scratched or dented. The biggest difference between doing it yourself with an HVLP and professional results lies in the gun.

This article will focus on the two types of guns: those fed from a hopper, or those that are box-fed. Before choosing one over the other, there are some key things to consider about each type.

The Hopper-Fed Powder Coating Gun

The standard¬†powder coating gun¬†is fed from a hopper. If you’ve ever seen smoke or fog coming out of someone’s garage, they were probably powder coating with one of these guns. The powder is stored in a container below the gun, and gravity feeds it through the system, atomizing it as it passes through the nozzle heating element.

The Pros of a Hopper-Fed System

The fact that the powder is gravity fed into the gun makes it easy to use. You can simply pour in your bag of powder into the hopper, and attach a grounding wire to the frame of the gun. The only maintenance is keeping a full hopper of coating – there’s no tube to clean out, and you don’t have to worry about the powder getting gummy inside of a tube.

Another benefit of a hopper-fed gun is that, if it’s adjusted properly, the majority of the powder will pass through the nozzle, rather than forming a cloud around your head as it falls out. This keeps the stylus cleaner for longer, and makes it easier to see what you’re doing.

The Cons of a Hopper-Fed System

The biggest drawback is much more obvious – when the hopper empties, so does the gun. You don’t have much time before this happens, either – about 25 minutes in normal weather conditions. While you can reprime the system by adding powder, the best method is to remove and refill the hopper.

A second drawback is that it’s difficult to focus on detailed work. Since the coating starts out as a cloud, you have to spray for a few seconds before it comes down enough to provide a clear path through which you can see your stylus. Also, because the coating starts out as a cloud, it can be difficult to judge how much you’re applying. If the coating is too thick, it will drop off of your product before it has time to cure properly. With practice though, this can be overcome with excellent judgment and control over the amount of powder applied.

The Box-Fed Powder Coating Gun

A box-fed gun works in an entirely different way. The powder is held in a small cup inside of the head, which can be refilled easily. You have more freedom to get into small or detailed areas because there’s no cloud of powder while you spray.

The Pros of a Box-Fed System

The first benefit is versatility. Box-fed guns are much easier to use, because you can see what you’re doing and focus on detail work. This puts your gun in the same category as HVLP and other professional equipment, which is why they cost significantly more than hopper-fed systems.

Another big benefit is that there’s no cloud of powder flying around the garage while you spray. This makes it much easier to control the amount of coating applied, and reduces overspray in your home or shop.

The Cons of a Box-Fed System

While there are plenty of benefits to using a box-fed gun, they’re not without their drawbacks. The number one issue is initial cost – these guns are much more expensive than their hopper-fed counterparts.

Another drawback of the box-fed system is that it requires constant attention during use. You can’t just pour some powder into a hopper and leave, because the gun will run out quickly, which wastes time and money. Instead, you must refill your cup after every couple of minutes, or risk ruining your piece by applying too much coating.