Airbrushes: Know the Lingo!

If we are going to talk about airbrushes, we need to speak the same language... as with any niche art form, it has it's own lingo and it's important that we are on the same page...

Airbrushes are defined by three characteristics:

#1. Paint Delivery System which can be further broken down into:

#2. Trigger Functionality which includes:

#3. Needle Size

Each of these characteristics serve a different purpose for each particular brush.... so let's discuss them further...

Paint Delivery Systems

Gravity Feed

Gravity feed airbrushes deliver paint to the needle/paint/air interface through a reservoir or cup positioned on top of the brush.

The size of the cup or reservoir varies from model to model - typically from 1/32 oz. to 1 oz. The small size of the cup or resevoir dictates the use or functionality of the brush.

A brush with a very small cup is meant to be used in applications where the volume of paint required is very small. Finger nail artists and model/miniuature artists find this size cup to be a good fit with their work.

The larger cups are used for a variety of applications where small amounts of paint are used, such as detailed automotive work, fine art, cake decorating, etc.

The basic idea with any gravity fed brush is that you would only mix a small amount of paint (perhaps in another small container or directly in the reservoir) and then use just that little bit of paint to paint on your piece.

Siphen Fed

Siphen fed airbrushes have a threaded or pressure fit (squeeze fit) connection at the base of the brush where a bottle filled with paint can be attached. The bottle has a tube in it that reaches to the bottom of the container. When air rushes past the top of the tube (i.e. when you trigger the air on) a pressure differential is created that causes the paint to rise up the tube and come in contact with the needle/air interface.

Siphen feed brushes (also called bottom feed) are typically used when larger quantities (i.e. greater than 1 oz) of paint will be required at a time or if you will consistently be using the same color over and over again.

T-shirt artists are by far the best example of a good siphen feed application as typically they consistently use the same set of colors to paint with. All of their color mixing is done on the t-shirt by layering colors as opposed to in a separate container.

The bottles that attach to these brushes vary in size from 1 oz to 8 oz. Typically, airbrushes are compatible with multiple size bottles.

Side Feed

Side feed airbrushes are a hybrid between a gravity feed and a bottom feed (or siphen feed).

Side feed brushes have a cup or reservoir that is mounted on either the right or left side of the brush. Rather than gravity pulling the paint onto the air/needle interface, these brushes, like the bottom fed one, use a siphen system to move the paint - however - rather than a physical tube that you can see, the siphen system is built right into the cup.

Side feed brushes were born from the frustration of artists having to "look over" or "past" the top mounted cups on the gravity feed systems when working on detail work. Ideally, the artist wants to look directly down at the needle tip as opposed to off to the side. Simply moving the cup to the side gave them a direct view of the work in front of them.

Trigger Functionality

Single Action

Single Action brushes are the simpler of the two trigger function designs. With the single action, the operations is simply ON or OFF. That is, as soon as the trigger is pulled back, both air and paint flow.

Because paint flows immediately these types of brushes are best used when painting with stencils or in applications where lots of detail is not required as artists find it difficult to achieve fine points of dagger strokes with this type of trigger.

Dual Action

Dual action brushes have triggers that require two steps to achieve paint flow. Initially, the trigger has to be pushed down to get the air flowing, and then, when the trigger is pulled back paint is released into the air/needle interface.

Dual action brushes allow for a lot finer control than single action.

Needle Size

The needle of the airbrush has one major function - it's tapered end regulates (limits) the amount of paint that is allowed to pass the nozzle. The finer the needle the airbrush has, the finer the detail you will be able to achieve.

So this begs the question "Why do they come in different sizes?". You would assume that the finer the better, right?

Well, simply, it is a function of paint. Paints with thicker, more dense pigment have difficulty passing through the small opening that a fine needle has ... so, thicker paints - thicker needles.

Most paints work perfectly fine with the fine needles with the exception of some textile paints and some automotive paints.