Choosing The Correct Spray Painting System
Conventional Spray Painting - The 3 Styles of Spray Gun
Suction Feed - Gravity Feed - Pressure Feed
Both conventional and HVLP spray painting systems offer a choice of three styles of spray gun: gravity feed, suction feed, and pressure feed. The names indicate how paint is fed into the gun (i.e. a gravity feed holds paint in a container on top of the gun, so liquid flows downward due to gravity) - and each comes with its own set of pros and cons and has different common uses, all of which this post will cover.
1/ Gravity feed
As mentioned above, a gravity feed style holds the paint or fluid in a container on top of the gun.
Gravity feeds require less air pressure to atomise the paint, providing the direct benefits of lower overspray, less paint wastage, and a greater level of control for the painter. Thanks to these advantages, the gravity feed gun typically delivers better finishes.
This style of spray gun is portable and versatile, and the associated cleanup is far easier than, say, that of a pressure feed gun.The gravity feed style allows you to efficiently spray paint in smaller volumes, making it particularly useful for touch-ups and less intense projects — but its main use is in auto refinishing.
Gravity guns come in two styles: mini and standard. The mini gun is a smaller version of the standard, and it’s designed specifically for touch-ups and fine detail work.
Downsides? The nature of the gravity feed system makes it difficult to paint with the gun upside down or in tilted positions — and because material needs to be able to flow easily downward with the force of gravity, this style doesn’t work well with heavy-bodied coatings.
2/ Suction feed
Also called a siphon feed, the suction feed style is essentially the inverse of the gravity feed, in that it holds the paint in a container underneath the gun (suctioning — or siphoning — the liquid upward). Similar to the gravity feed in portability and affordability, the suction feed offers easy and versatile spraying, allowing you to use the gun upside down or in whatever position proves necessary.
Atomisation of the paint occurs automatically which is both an advantage and disadvantage, as it lets you spray smoothly and evenly but with limited control.
The container on a suction feed spray gun is typically bigger allowing the user to paint larger surfaces with less refilling. The suction feed is best-suited to lighter-bodied paints and fluids, and it’s commonly used for wood and metal finishing.
3/ Pressure feed
The third and final style of spray gun, the pressure feed pulls paint from a remote pressure pot, allowing you to modulate the fluid and air pressure separately and therefore offering the best control of any of the styles. Since you can increase or decrease the pressure, it’s equally efficient for liquids of all viscosities — but in general, the pressure feed is better for higher-volume applications.
Pressure pots are excellent if you require a lot of paint, as they’re available in a variety of sizes from two litres to 20 (and up to 120 on special order). Since the paint is held independently, the weight of the gun is reduced, which increases mobility and comfort for the painter.
Its main disadvantages? Because you have to buy a separate pressure tank, the pressure feed system incurs a higher cost than either the gravity feed or the suction feed.
You also have two hoses to deal with (the usual air hose and an additional fluid hose from the pressure pot) — and the pressure feed system takes more effort to clean, as the fluid line can vary in length up to 10 metres.
If you do not know what you need, get in touch and I will ensure you get the best product for your application.