Q: What is an Airbrush?
An airbrush is a small pneumatic (air operated) tool that sprays liquids of suitable viscosity such as paints, stains, inks, dyes, glazes etc. It is held in the hand and used like a pen.
Q. How does an Airbrush work?
The airbrush requires a source of compressed air. When the trigger on the airbrush is pressed the air is turned on which, by venturi action draws the liquid through the nozzle and atomises it just in front of the tip/nozzle. The amount of liquid sprayed is controlled by how far the needle is pulled back with the trigger. On some airbrushes this can be set with a stop.
Q. What type of Airbrush is best for me?
This depends on your application. Airbrushes come in 2 main types:-
- Single Action – where pressing on the trigger simultaneously turns on the air and sprays the liquid in the paint cup. This type of airbrush is mechanically simpler and consequently a lower cost product but does not offer the very fine control available with the Double Action Type.
- Double Action – where pressing down on the trigger turns the air flow on and releasing pressure on the trigger turns the air off. Pulling back on the trigger opens the needle/nozzle valve, which releases the paint into the air stream. This type of airbrush offers very fine control for the skilled operator.
Some airbrushes are available with different size needle/nozzle arrangements. These can simply be categorised as fine, medium or heavy. Generally the larger the nozzle, the bigger the spray pattern produced with the capability to spray thicker liquids.
Q. What do I need to before I can start spraying?
These are the four things required before you can spray:
- An airbrush
- A source of compressed air, either a compressor or a propellant can (similar to an aerosol).
- A means of connecting the airbrush to the air supply. For a compressor this is simply a hose with suitable connectors both ends. For a propellant can you will need a hose and a propellant can regulator (this connects the hose to the propellant can).
- Some Paint!
Q. I’m confused, why are there so many different types of Airbrush?
Good question! All airbrushes will convert liquid (paint for instance), into a fine spray. Most models will perform this task to a standard that is way above the beginners needs, so in most cases your choice of model will be determined by whichever style of paint cup suits your type of spraying. If you want to spray a ceiling for instance, then you will need a model with a swivelable side cup, so that the airbrush can point vertically, whilst the paint cup remains horizontal.
If you plan on changing colours often, then consider a model with a removable bottle. These simply pull out of the airbrush body.
If you are using tiny amounts of colour, in nail-art for instance, then the smallest of paint reservoirs will be adequate. This has the added benefit of giving a clearer view of your workpiece which is ideal for fine detail. One other consideration is the type of paint to be spayed. If you plan on using cellulose based paints, then you will require a model that has PTFE (Teflon) seals inside. These are resistant to aggressive solvents, whereas rubber seals are rapidly degraded, and fail leading to poor spray performance.
Q. What type of surfaces can be sprayed?
All absorbent surfaces can be sprayed. Non-absorbent surfaces can be sprayed with the appropriate paint. Sometimes surfaces will need to be prepared with a suitable primer or base coat to accept your required finish. This information is generally available from the paint/finish manufacturer.
Q. What types of paints can be Airbrushed?
Any paint (or liquid) can be sprayed providing it can be thinned to the required consistency (viscosity) that allows the paint to flow through the airbrush. This includes acrylics, watercolours, oils, enamels, automotive finishes, alkyds.
For paints that include aggressive solvents (i.e. cellulose) you will need an airbrush that contains no rubber seals or valve seats. Rubber is normally replaced by PTFE for such applications.
Q. What about cleaning?
Cleaning is quite straightforward. Simply rinse the wetted areas of the brush with a suitable solvent, using a brush if necessary and wash out the cups/ bottles. Then spray through with the suitable solvent until the airbrush is thoroughly clean. It is essential to be very careful between colour changes to ensure there is no residue left. If using dark and light colours together it is worth considering having 2 or more airbrushes to eliminate cross contamination of colours.
At the end of your session, clean your airbrushes thoroughly. Many manufacturers supply ready made airbrush cleaner in aerosol form. After cleaning lubricate the needle/nozzle, needle packing and air valve lightly with airbrush lubricant to prevent sticking.
Q. What about masking?
Masking is possible using masking tapes, frisket (which is a self adhesive masking film) or other proprietary films or stencils.
Q. What about an air source?
You can use a compressor of which there are many types but it must have an adjustable regulated output or a propellant can with a regulator or a spare tyre with a regulator.
Q. How much air is needed?
You will need a minimum of 0.8 CFM (23 litres per minute) at 40 psi (2.7 bar) per airbrush. Pressure setting is adjusted to suit your application.
Q. Is there any instruction/educational material available?
Yes. Visit our Books section for a wide selection of modelling titles. Alternative YouTube is excellent platform for airbrushing tip and techniques
Q. What Health and Safety considerations should I be aware of?
Read and understand the Health and Safety instructions from the manufacturer of the product you are spraying.
- Do not inhale atomised liquids – use adequate ventilation.
- Some paints (e.g. cellulose), stains and airbrush cleaning fluids amongst others contain very aggressive solvents and you must not inhale the vapour and you must prevent contact with the skin/eyes etc.
- Extractors are available for spraying operations and if applicable should be used.
- Pneumatic tools are not suitable for use by unsupervised children.
- Compressed air/gases can be dangerous. Never use an airbrush in a manner that may cause an injection hazard to the body – air and or liquids in the bloodstream can be fatal.
- Airbrush needles are ground to a very sharp point. Pay attention when using your airbrush.
- If in doubt, leave it to the professionals.
- Dispose of all paints/liquids responsibly and in accordance with applicable laws.
Q. Why does 1/4″ BSP seem so much bigger than 1/4 of an inch?
We are asked this a lot, and the answer is rather technical!
A 1/4″ BSP male threaded outlet has a diameter of around 13mm. This is because the thread is based on an old British Standard for Pipe threads (BSP) that specified threads based on the BORE of the pipe. Thus a 1/4″ BSP thread fitted on the outside of a pipe with a 1/4″ (6.35mm) bore, and so had to be much bigger to fit onto it.
The same is true for all BSP threads, and 1/8″ BSP has a diameter of around 9mm.
