Airbrushes

What is an Airbrush?

The airbrush is a mechanical paintbrush or a fancy spray can. By placing paint in an attachment to the airbrush and then applying some kind air pressure, the artist can achieve anything from pencil-thin lines of color, to uniform coverage of broad areas. Subtle tonal gradations are easy to achieve, and the artist can mix their own particular color.

Some frequently used terms

Bar = a unit of atmospheric pressure
CFM = cubic feet per minute
FAD = free air delivered (volume of air delivered by the compressor)
Hard masking = masking that adheres to the surface to produce a clean, sharp line when airbrushed.
Liquid Mask = usually a liquid-rubber compound that can be brushed on, painted over when dry, and then rubbed away.
Pigment = finely ground solids which are the basis of color in paint.
Propellant = source that provides air for the airbrush
PSI = pounds per square inch - output of a compressor- surface air pressure above atmosphereic pressure.
Pulsing = pulsating airflow from a compressor
Reamer needle = used to clean nozzle; a flat needle with a taper
Regulator = controls air pressure from a compressor (or CO2 tank)
Soft-edged = a type of masking effect where the mask is applied loosley and resulting edges are softand not clearly defined.
Solvents = used to loosen dryed paint; great for cleaning an airbrush.
Spatter = an effect to produce a grainy spray by irregular flow of paint and less air pressure.
Stipple = small dots in a fine controled line; a controled spatter
Tack = strenghth of adhesive

Types of Airbrushes

External Atomization
This is what the simplest airbrush uses. The mix of air and paint occurs _outside_ the airbrush. The resulting spray is a bit uneven.

Internal Atomization
Most airbrushes use this type. The paint and the air are mixed inside the airbrush (in the nozzle). A finer and more even spray is produced.

Double-Action
Both air and paint flow through the airbrush. The trigger can be pushed down for air and pulled back for paint, controlling the ratio of paint to air and allowing the artist to control the width of the spray _as_ he/she is painting.

Single-Action
Paint and air are mixed inside the airbrush. The trigger can be pressed for air. The amount of paint (i.e. width of spray) must be preset by adjusting a knob on the end of the airbrush body.

Spray Gun
The most basic type of airbrush. These are usually siphon fed. Air is blown through the brush and over the paint _outside_ of the brush. Spray is less fine than most airbrushes. (External Mix)

Feed types:

Gravity Feed
A _gravity-fed_ airbrush will have a color cup permanently mounted ontop of the airbrush body. The cup can be large, or merely a recess in the body of the brush.

Siphon Feed
Airbrushes that are siphon fed have either a jar that can be screwed on underneath the brush, or a smaller color cup that fits underneath.

Brands and Models

Badger

• 350 (external mix, siphon feed)
  
• 200 (single action, siphon feed)
  
• 100 (double action, gravity feed)
  
• 150 (double action, siphon feed)

Paasche

• F&H series (external mix, siphon feed)
  
• VIR (double action, gravity feed)
  
• VLS (double action, siphon feed)

Thayer & Chandler

• A & AA (double action, side cup feed)
  
• C (double action, siphon feed)
  
• E & G (single action, siphon feed)

Some other brands are:

Conopois
Hohmi
Iwata
Olympus
De Vilbiss
Rich
Model Master (from Testors)

Air Supply

A listing of possible air for airbrushes

Air Cans:

• cans of compressed air
  
• +: silent, easily portable, simple to use, inexpensive for occasional use
  
• -:regular use is expensive, air pressure goes down as can gets empty or cold

Automatic compressor:

• this type of compressor uses an resevoir. When the resevoir is filled to a certain, preset pressure, it shuts itself off automatically. When pressure drops below the preset level during use, resumes filling the resevoir.
  
• +:motor does not run constantly so reduces chance of overheating
  
• -:tend to be very expensive

CO2 tank:

• (with pressure regulator) these are most widely used as the CO2 supply for softdrink machines.
  
• +:+ silent, can go for quite sometime before needing refill. Refills are inexpensive.
  
• -:need to buy a pressure regulator to use with tank since pressure straight from the tank is too high for an airbrush. Heavy- definitely not portable.

Car Tires:

• (self explanitory...)
  
• +:cheap, you can pick up a used one just about anywhere. Can be refilled and reused often. Silent.
  
• -:Needs refilling very often. Dirty. Pressure to airbrush will drop as tire deflates.

Diaphram compressor:

• uses a diaphram to pump the air into the compressor and out the airbrush
  
• +:least expensive type of the compressors.
  
• -:diaphram produces a pulsing of airflow that can sometimes be seen in the artwork.

Piston compressor:

• uses a piston to compress the air.
  
• +:does not have the pulsating quality that the diaphram type has.
  
• -:oil that is used to lubricate the pistons can get into the airbrush occasionally. Can overheat if used for a long period of time.

Storage compressor:

• contains a resevoir tank for the compressed air, so that pulsing does not occur through the airbrush.
  
• +:no pulsing effect
  
• -:simple types run continuously and can overheat

Tips on Cleaning an Airbrush

Useful solvents to clean an airbrush (after taking it apart) are:

methyl hydrate (commonly used solvent)
brake fluid (great for stubborn cases)

Misc

Some useful items:

Airbrush holder: keeps ab horizontal when not being used, preventing it from tipping over (when using a jar that's not completely filled), or spillage of paint (when using a color cup)

spatter cap: gives the spatter effect

stipple cap: produced stippling effect

References

The book no airbrush artist should be without:

The Airbrush Artist's Handbook
Fred Dell and Andy Charlesworth
Running Press Book Publishers (c 1986)
ISBN 0-89471-466-x