Airbrush Basics FAQ

  • Q. How do airbrushes work?

    The airbrush relies on the venturi effect to draw paint / medium into a fast moving flow of air, where the paint / medium is then atomised into a fine spray, this fine spray is then projected by the flow of fast moving air until it reaches the surface being painted.
  • Q. How exactly do airbrushes work?

    (The following applies to the most popular double action type airbrushes)

    When the airbrush trigger is pressed, air from the air valve is allowed to flow through the air channels in the airbrush & exits from around the outside of the nozzle tip. At this point no paint is sprayed, as the needle is still fully forward & seated against the inside of the nozzle. As the trigger is pulled back, the needle is drawn back from the nozzle creating a circular gap around the needle tip which allows paint to flow, the paint is then drawn into & atomised by the airflow giving the resulting spray pattern - thanks to the venturi effect.
  • Q. What types of airbrushes are available?

    There are many different type of airbrushes available from many manufacturers, however they all have three important features which separate them - Where atomisation occurs, The Trigger / Action type & the paint feed system used. Understanding these features will assist you in making an informed choice regarding which type of airbrush is most suited to you

    Where atomisation occurs;

    This can happen in two places, completely outside the brush, with the paint source often being in a jar or container mounted in front of the main body - known as external mix & at the very tip of the nozzle with the paint & air sources both coming from the airbrushes main body - known as internal mix.

    Externally mix airbrushes are far less popular than they once were & can now generally only be found at the lower end of the market. The reason for this is that because paint atomisation occurs outside the body of the airbrush, the process is far less controlled & open to external influences, this results in a coarser & less consistent spray pattern than in an internal mix airbrush. That being said, external mix airbrushes are far simpler than internal mix airbrushes, which results in easier cleaning & maintenance.

    Internal mix airbrushes, although their name suggests that air & paint is mixed "internally", actually mix at the very tip of the nozzle. This method allows for far more precise control over the process of atomization, which in turn allows a far more consistent & finer spray than can be achieved with an external mix airbrush.

    The trigger / action type;

    There are two types of triggers actions used, single action & double action.

    Single action - when the trigger is pressed, air & paint both start to flow simultaneously, to adjust the volume of paint being sprayed involves turning a separate flow control on the body of the airbrush. So although it's possible to adjust the paint volume, it is not feasible to do it mid spray. Single action airbrushes are slightly simpler that their double action counterparts, with a slightly lower parts count.

    Double Action - When the trigger is depressed on a double action airbrush, air starts to flow through the brush, but paint does not. When the trigger is pulled backwards, paint then starts to flow. Paint flow control on dual action brushes is variable, the further back the trigger is pulled - the more paint flows. Paint flow is very controllable & can be adjusted gradually from no flow to maximum flow with finite accuracy. There are a few airbrushes, like the Harder & Steenbeck Grafo & Colani which use was is called "continuous double action", where the air & paint flow are both controlled by the backwards movement of the trigger. On these continuous double action airbrushes, the first portion of trigger travel is reserved for air & the remainder of the travel controls paint flow in the same manner as a regular double action airbrush. Double action brushes are slightly more complex than single actions, but generally speaking the finite degree of control they give far outweighs the slight added complexity.

    There is a school of thought that for the beginners in airbrushing, the single action airbrush is more suitable due to the shallower learning curve & mechanical simplicity it offers. However the dual action is not really significantly more difficult, if any, to master than the single action & it is also not that much more complex. The result is that many who begin with a single action airbrush soon find themselves wishing they had purchased a double action airbrush to begin with, they then go on to purchase a double action airbrush only to let their single action gather dust, which is not exactly economical.

    The Paint Feed System;

    This is the third fundamental difference that you will find between designs & describes how paint is supplied to the airbrush. There are three differing type of paint feeds available;

    Gravity Feed
    - The airbrushes paint container or colour cup, is fitted directly to the top of the airbrush, usually by a screw or push fit & in some models permanently fitted. Gravity fed brushes are more capable of fine detail work, because less air pressure is required to get the paint from the cup to the nozzle than on other feed systems. Due to the lower air pressures required gravity fed brushes can produce very fine spray patterns & can be used more closely to the work surface than other feed methods. Because of the route paint takes in the gravity feed system, it is more suited to using minimal paint volumes where required, again because of the simpler route the cleaning of Gravity fed brushes is also slightly easier. Some manufacturers, like Harder & Steenbeck offer conversion kit which allow gravity fed airbrushes to utilise Siphon / Bottom feed paint jars & bottles.

    On the downside, if you require to change colours often this is more difficult with the gravity fed brush as the cup will have to be removed, cleaned & refilled for each colour you use. Gravity fed brushes are also less suited to large area coverage due to the size of the paint cup fitted.

    Siphon / bottom feed - The paint container, which can be a cup or a bottle, is fitted to the bottom of the airbrush, through a simple push fit inlet pipe. Various adapters can be fitted to the inlet to allow paint bottles of various sizes & types to be used, from small glass jars to large paint bottles. Adaptors can be fitted that allow paint bottles such as those that Createx paint & several other manufacturers paints are supplied in to be fitted directly to the airbrush without decanting , this allows rapid colour changes to be made & can offer extended continuous painting for larger areas when compared to the gravity feed system. The placement of the paint container of the bottom feed airbrush also allows the user to have a clear view of their work, without the obstruction of a cup mounted on the top of the airbrush.

    The downsides of this system is the longer distance that the paint is required to travel - this requires slightly higher air pressure & consequently this feed system cannot offer quite the degree of fine spray that the gravity fed system does. This system is slightly more difficult to clean in comparison to gravity feed & requires slightly more paint as a minimum to operate than the gravity brush.

    Side Feed - The side feed system, as its name implies if fed from the side of the airbrush. This system can be fitted with both gravity type paint cups & siphon feed bottles when fitted with the appropriate adaptors, this allows the side feed system to offer most of the benefits of both the Gravity & Siphon / Bottom feed system.


    Some final points;

    As you can see there are a few things to consider when choosing an airbrush, mainly dictated by how you propose to use it. In addition to the points described above, price will obviously be a deciding factor in you decision - as with many things if life the old adage of "you get what you pay for" is also perfectly true for airbrushes. A final point worth considering is the availability of spare parts, we would advise that whatever make / model you choose, you should find out that at least replacement needles, nozzles & seals are available.

    Thank you for reading & happy shopping.

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